5.7x28mm Trials (pic heavy)

[Trent]

Preface Edit 1/2/2014:

WARNING ABOUT MAXIMUM LOADS AND USE OF UNDOCUMENTED LOADS.

This thread documents use of powders in the 5.7x28mm cartridge that is not found in any current printed reloading book. (And later, some that ARE). I will make note when I am using PUBLISHED data. Unless I indicate I'm using published data, assume that I'm a nut job and don't do what I do.

All testing to date was done ONLY with the PS90 rifle, not with the FiveSeven handgun.

I TAKE NO RESPONSIBILITY FOR USE OR MISUSE OF DATA CONTAINED IN THIS THREAD. PERIOD. THERE IS AN INHERENT DANGER WITH GOING OFF THE BEATEN PATH. IF THERE IS ANY DOUBT AS TO WHETHER YOU SHOULD USE THIS DATA AS-IS, PLEASE TAKE NOTE THAT I AM USING BODY ARMOR TO SHIELD MY FACE FROM MY RIFLE WHEN TESTING LOADS. THAT SHOULD TELL YOU SOMETHING! JUST BECAUSE I DIDN'T BLOW MY FACE OFF (YET) DOESN'T MEAN YOUR RIFLE WILL BEHAVE AS KINDLY AS MINE. POWDER VARIES LOT TO LOT AND YOU MIGHT USE DIFFERENT PRIMERS, TECHNIQUES, ETC, AND GET *DRAMATICALLY* DIFFERENT RESULTS.

(By "dramatic", I mean your rifle may explode, where mine didn't. Or vice versa. We'll see where this all leads this year...)



This thread is intended to be a journal of sorts, as I begin the journey of loading for this cartridge. Normally I wouldn't bother doing any sort of write-up, because most ammo we reload is pretty much like all other ammo we reload.

Except for these persnickity buggers.

NOTE: This cartridge is a real pain to reload, and takes every ounce of attention and every bit of skill you can deliver to the bench. I *absolutely do not recommend* reloading this cartridge if you are a novice reloader. Get some bench time under your belt and revisit it in the future, if you are new(ish) to reloading. A mistake as small as a bad powder measurement of .1 grain off, could ruin your gun, your day, and perhaps your body. You'll see later that even respected, published reloading manuals contain errors for reloading this cartridge. Dimensions, equipment, and measurements must be *absolutely precise* to reload this round with any semblance of safety.



The first thing to pay attention to is that the 5.7x28mm platforms are are blow-back operation. To facilitate this mechanism the cases are coated in a super-ultra-mega-secret-concoction of dry film lubricant. (Many attempts have been made to duplicate this coating and no one has been able to successfully do so, to the best of my knowledge.)

This presents some significant challenges as tumbling in any sort of media is right out - it'll strip the cases of this dry film lubricant, which will effectively ruin them. Cases without the dry film lubricant won't be able to extract properly; the result of which is sheared off rims, and stuck cases in the chamber of the firearm.

My adventure started last night, when I mixed a 4:1 ratio of Water to Simple Green in a plastic tub. I used the basket from my ultrasonic cleaner to put the brass in. (NOTE: I didn't actually USE the ultrasonic cleaner, just the basket, in a tupperware tub.) I Set the kitchen timer for 10 minutes and dunked the cases in to the solution in the tupperware tub. Then, at the 1:00 minute warning, I began agitating them by hand.

If you leave them in too long, you'll ruin the coating.

If the mixture of solvent is too strong, you'll ruin the coating.

The 5.7x28mm casing is so tiny that a few of them slipped through the slots of my ultrasonic basket and I had to pick them out with pliers.

Once out, I shook the simple green solution out of the cases, and dunked them in a tub of plain tap water. I agitated them, then plucked them out, shook the water out of the cases, and laid them on a sheet of cardboard to dry for 24 hours.

Tonight, after 24 hours had elapsed, all of the cases were dry as a bone. I began the process of sizing... and found that my Redding die couldn't push the shoulders back far enough.

With the Redding full length sizing die adjusted down to make contact with the Redding #34 shellholder:



The shoulder wasn't pushed back to factory spec (.910 to the start of the shoulder curve).

Factory index round (SS197)


Resized casing from the Redding die.


It's difficult to see that the shoulder is pushed forward above, but much easier to see that the round doesn't index right in the chamber of the barrel, using a depth reading:

Factory round; .122 protrusion to rear of case



Resized round: .131 protrusion to rear of case (Best I could do... can't get it back further without removing metal from the bottom of the die or the face of the shell holder)


Tiny little buggers:


Some of the factory cases are crimped. Some aren't. No idea why. But I had to take care of the crimps. While this uniformer isn't the BEST tool for the job, it worked acceptably.


I elected to use CCI #400 primers as they are thinner cups than some of my other primer types (.020" cup thickness). This will help me read pressure signs easier, than if I used a thicker cup primer.


Next task. I dialed "5.1" in to the auto dispenser and it kicked out 9 grains. Yeah. That's not gonna work.


I changed the leveling knobs so it's pushing out powder slower, re-calibrated, and it started dumping close to the mark.

Better.


Verified it was "on" with my 10-10 scale. (This is from a later session when I'd increased my initial load a couple steps.)


It was about 1/2 of a 10th of a grain off, but close enough.


Since I'm using Longshot (a shotgun powder), for which there is no published data for, I turned to the internet for help. On the FN Forums I came across a post where a member had done some load development with Longshot (he's also on the fiveseven forum, and a respected source). I'll trust his start load, but working up from there on my own ...

My initial loads for Longshot w/ 40gr Hornaday V-Max:

5.1gr Starting load
6.2gr Max load (this showed overpressure signs on the original data remarks, so it's probably actually over max... we'll see).

These are comically small in my powder funnel. (Also somewhat painful to hold on to after a long session, hands started cramping.)



The projectile;


The starting powder charge; Less than 50% case capacity is used so one has to be very careful not to doublecharge a case. Fortunately, you can "shake" a case which is loaded to up to 5.5gr and audibly hear and tactile feel the powder moving in the case. So it's easy to tell if you have a doubt about a cartridge.




(continued)

 

[Trent]

Little tiny things are hard to hold on to:


AAAAND my first major error. (Not deep enough seating to seat the bullet, but deep enough to lodge the bullet in to the seating die...)


Once I got that put back together, I indexed the seater off of a factory round (dialing it down until contact was made)


Then I seated my first round, and there was only a .004" difference between my round and the factory round. 1/8th of a turn on the seating die, and it's spot on.

(I've used this trick before when changing bullet weights; I can use an "index round" of that type. I screw the seating die insert down until it makes contact, remove the index round, and then go 1/8 turn more, and "boom", it's on. No muss, no fuss.)



First five rounds done, and done:



Will finish up the test loads tomorrow morning and go shoot them through the chrony tomorrow afternoon (unless I get called in to work..)

 

[Trent]

NOTE: I know that I'm loading rounds which have a shoulder that's .010" avg longer datum point than factory rounds. However, test chambering rounds showed no issues in the pistol or rifle (I didn't have to "force" them). I'm firing the test rounds out of the PS90 with the "safety sear" so in the event a round won't allow the bolt to come fully forward, the sear won't disconnect. (There's more material between me and the cartridge on a PS90, compared to the handgun.. so I'm doing my test fires from the rifle)

One other thing to note; the Redding die uses an incredibly tight neck tension - mine was .005" undersized from the bullet diameter. That's the tightest neck tension I've ever seen on a factory die.

I imagine this is to compensate some for the inability to "glue" the bullets in to the casing. Yes, you read that right. The factory actually GLUES these bullets in to the dang casing, on factory ammo. No one really seems to know what type of glue they use, and I don't think anyone has ever tried to replicate it. I'm content with the redding decision to run .219" inside diameter on the neck. (Bullet diameter is .224 so this gives .005" neck tension - or, in other words REALLY DAMN TIGHT.)

 

[Trent]

One other thing I didn't mention earlier. Above you see I set the overall length off of a factory index round.

The Lyman 59th book was WRONG about overall length. Compared to the SS197 factory ammo, they were a full .060" *wrong* on cartridge overall length for the 40 gr Hornaday V-Max bullet!

I made a notation in my book so I don't forget at some future date.


This image shows how much off their measurement is. Calipers dialed to the book, factory round indexed. Notice how about half the ballistic tip is above the caliper top?



Actual factory round measurement. (I measured several and they were all +/- .001" of this)




NOTE: This is VERY concerning and shows why you need to use some serious common sense when loading high-pressure / highly-sensitive cartridges, even if you are following a respected reloading manual. Misprints and errors DO occur.


For what it's worth, .060" setback on a diminutive round such as the 5.7x28mm on a max load could mean the difference between a good day at the range, and this:



Source: http://www.thefirearmblog.com/blog/2012/02/27/fn-five-seven-kaboom/

 

[Peter M. Eick]

Very nice writeup and great pictures. My compliments on pointing out the details of the 57x28.

 

[Walkalong]

In my opinion, the biggest problem with loading the 5.7X28 is the shoulder. It gets blown forward .030 to .040 or so when fired in these actions. Then it is pushed back when sizing. That is a lot of movement.This causes the case to separate at the shoulder after a certain number of firings. Most folks toss cases based on the number of rounds fired and the pressure they are loaded to. They cannot be checked internally for signs of separation like regular bottle necked brass, as they do not suffer from case stretching near the web, but fail at the shoulder first.

The next thing to be sure of is consistent powder charging and good neck tension.

 

[ClickClickD'oh]

And we wonder why there are really only three companies making these little lovelies for us.

 

[Trent]

walkalong - I measured 0.050 to .060 shoulder movement on factory SS197 and SS195.

I have *zero* desire to load these cases to the point of failure. I've seen too many pictures of blown up FN FiveSevens and PS90's over the years. One of the reasons I put off reloading this round for so long, was the horrible failure mode of the firearms. (They don't vent pressure well on a failure.. they just sort of catastrophically shatter sending bits of metal and plastic in to the unfortunate person holding it).

Part of the reason I made the decision to reload this cartridge at this point, is SS197 has been difficult to come by for a couple of years now; it costs over 2x as much as it did in 2006 (last time I bought a 2k round case it cost me $640), and the only other mainstream factory load (American Eagle) I detected serious projectile set-back issues, when fired out of the PS90. I was measuring as much as .250" setback on Federal American Eagle ammunition when chambered in the PS90. This was due to the FMJ bullets they use having too rounded of a nose, it would impact the barrel cut and stop, forcefully. 5.7x28mm bullets need a VERY pointed nose to chamber properly.

That is exceptionally dangerous on a cartridge that is this finicky about pressures. The only thing that probably saved my PS90 when shooting the American Eagle ammo was their SS197 clone load is relatively mellow, compared to law enforcement loadings. (Reduced pressure / velocity.) Even so - I saw far more dangerous signs of overpressure on some fired American Eagle cartridges than I have ever seen on Fiocci, including flow of the brass itself, pierced primers, and woefully stretched cases.

(I'll leave Elite ammo for a different topic on a different day... I wouldn't touch the stuff, personally)

I've been handloading ammunition now for 18 years. I reload over two dozen different cartridges, including 50 BMG. I *do* consider myself an expert on reloading, but even so, this is the first time I've ever been real skittish about making ammunition.

This being said, after shooting the Federal American Eagle ammunition, I am *confident* that I can load a superior round. I've no desire to experiment with heavy bullets, or anything of that sort. I'm just looking for a replication of SS197 and I'll stick with 40 gr Hornaday V-Max. I'll play with velocity a little, within a safe band, and test a couple of different powders. I'll also test the accuracy against SS197 factory loads at 50, 100, and 200 yards and compare with the groups I shot in High Power from 2013. (I'd shot master level with the PS90 in 2013, we'll see if it can hit high master ...)

I'm currently debating via e-mail with Redding about their messed up die, not sizing rounds enough. I need at least another .009" of shoulder movement to get the casing back to factory tolerances, and their die isn't doing it. (They actually suggested I adjust the die to make contact, then lower the ram and turn it another 1/4" of a turn. Already been there, and done that; I'm camming that die with enough force that I'm worried about my press bearings. It got me from .015" to .009" but that's still not enough).

I don't like these reloaded rounds having an extra .009" of case hanging out the back of the breech when the ignition starts. The reason for this is the round and the barrel and slide all move rearward together for awhile, the breech doesn't lock, since it's a blowback pistol. That means I have an extra .009" of unsupported brass under peak pressures for the first millisecond or so, at maximum chamber pressure. With about .090" of case already being unsupported, adding an additional .009" of unsupported case raises the surface area exposed to the maximum chamber pressure by 10%. (!!!!)

That's enough to be somewhat alarming. And I need a new die, to correct it (my lathe is still down, I can't turn the die down myself).

So I'm only loading up to the half-way point of the initial test loads (5.1 gr to 5.6 gr of Longshot). I'll skip the higher pressure testing (5.7gr to 6.2gr) until I get a "good" sizing die to use that actually hits the correct dimensions.

 

[ATLDave]

Wow, what a wonderfully informative thread! Thank you, Trent, for sharing all of this information. It will be very valuable to the reloader of 5.7s. And perhaps even more valuable to those of us who are now dissuaded from ever acquiring or attempting to load for one of these guns!

 

[Trent]

ATLDave - this thread will continue to grow as I actually test the rounds. I'll shoot them through a chronograph and also for group size for accuracy. Starting with the longshot powder, will test more powders as I go.

I have an old Class IIA vest that's way out of date, that I will use when I test fire them. I'll lay one of the ballistic panels over the top and side of the PS90, to separate my face from the chamber of the PS90 (uncomfortable testing up to max load with the chamber right against my face...). My hands will be protected (mostly) with Kevlar reinforced motorcycle racing gloves. I'm erring on the side of paranoia here.

Hopefully the thread won't end with a Kaboom, but ... I'm taking some steps to mitigate the damage if it does.

Also, a kaboom won't stop the testing - I have several PS90 rifles in the safe. (Had 12 when I closed my gun shop down in '09, still have 9 of them)

 

[Trent]

Update; still communicating with Redding back & forth over e-mail. Trying to get a new die sent or this one modified so it can hit the correct specs. Further testing will be on hold until I can hit the correct dimensions.

(Wish my damn lathe was working, this could have been solved already.)

 

[Walkalong]

The first time I measured the shoulder location on fired 5.7X28 vs new rounds I did the old . .. ..

It gets your attention.

 

[Jesse Heywood]

You said your lathe is out of commission. How about filing off the top of the shell holder?

 

[Trent]

Jesse - I thought about sanding it off or hand-grinding it. But I want to see what Redding will do, first.

Never packed ballistic armor to the range before. The date of manufacture on the ballistic panel I brought along today was "July 1986", so I don't trust it to stop a bullet. But I think it'd do fine catching fragments off of an exploding rifle, so it still has a purpose.




I was obviously the only one stupid enough to go to the range today. No tire tracks at the gate.



The range sure does look pretty after a fresh snowfall, though.



Today I earned a new punch hole on my man-card. "Grow Snot-cicles". I haven't shaved since mid October and I've never really grown facial hair before, so it was quite the experience.

Temperature on my anemometer was 16.2 degrees Farenheight, and I had a 15mph crosswind.



Because of the crosswind and the desire to get SOME sort of accuracy reference, I set up on the 50 yard line using NRA A23-5 targets. 4wd was handy. I'm glad my wife didn't need her SUV today, my mustang wouldn't have fared this well.




Setup was rather straightforward.



I brought 3 factory and 5 handloads to test.



But I forgot my shell catcher, so I had to pick brass up out of the snow. As they are too small to pick up with gloves on, I had to fish around with bare fingers. Did I mention it was only 16F???



After shooting 5 reference groups with factory loads, I started in on the hand loads.

The factory ammunition performed predictably well.



First batch of handloads.



It was here that I realized any sort of accuracy testing was going to be absolutely impossible with the 1980's era thick-as-a-brick Kevlar panel. I could get neither cheek weld, nor shoulder weld.



But as I value my face more than my aim, I made due.

Before I proceed with ballistic findings and measurements, I will make a few choice remarks.

* Had to use the shade on the chrono to get it to pick up on rounds, it was overcast and saturating the sensors with light.

* Had to get the bullets to fly REAL damn close to the chronograph, for it to pick up on them. I mean, within a half an INCH. I burned through some SS197 getting it set up right. And I was very nervous about shooting my chronograph, but fortunately, didn't.

* Loading 5.7x28 PS90 magazines requires removal of gloves. Did I mention it was 16F? It hurt.

* Picking brass out of snow sucks. Next time I'll pack the brass catcher.

* Walking to the target for no particular reason helps circulate the blood. I didn't need to see the holes, but I did need to move, so going back and forth helped keep my heart rate up.

* Snotcicles feel really strange. But the cold air sure cleared up my sinuses!

* Shooting things is fun. Except when it's 16F.

* This was the first time I was *happy* to leave the shooting range.

(Continued)

 

[Trent]

(Waiting on my laptop to warm up before I post more - posting from my tablet right now but my chrony data is on the laptop, which currently has a layer of condensation on it. So I'll let it warm up and dry out before turning it on...)

Meanwhile. Coffee. I need to thaw out, too.

 

[Trent]

Conversation continues with Redding. They've asked me to send in the dies, 5 fired cases, and the shell holder.

Trenton-

It is per our warranty policy to not alter dies that are within Saami specs. We can't shorten the die. What we can do, however, is have you send the die back with 5 fired cases from your FN's chamber and analyze both the die and the cases. If our die is out of spec, it will be replaced as per our warranty. Our dies are cut with a one piece reamer on CNC machines, so if one is out-of-spec, there might be 100 at that, but as always, we are happy to have a look at anything awry. In addition, its our shellholder you are using correct? If so, do send that in to us to, and we can have a look at the whole picture. If you would also print out this email as a record of the problem, we'd appreciate it.

We thank you for your patronage and usage of our gear.

`Rick

My response:

Rick, will do! I have a big pile of once fired brass so sending some is not an issue.

Yes I am using your shellholder, #34.

I bought these dies over *5* years ago (7/7/2008) from MidwayUSA, and I am just now am getting around to using them. So this is not a current production die set!

The redding shellholder #34 was bought 7/18/2008 from MidwayUSA, so it is also not current or recent production.

5.7x28mm and kabooms seem to go hand in hand, so I’ve been nervous about reloading for it (hence the timespan between purchase and first use). But ammo supply and cost of ammo is a real **** right now for these, and really have no choice if I want to keep shooting.

 

[Trent]

I'll get some pics of brass once I dry it out.

Velocity information (fired from PS90):

SS197SR:
Low: 2041 fps
High: 2099 fps
Avg: 2083 fps
ES: 58 fps
SD: 24

SS195:
Low: 2515 fps
High: 2554 fps
Avg: 2535 fps
ES: 39 fps
SD: 15
(I've LONG said that SS195 was the most accurate commercial ammunition for the PS90, and now the numbers prove why.... the ammo is so consistent!)

Federal American Eagle:
Low: 2008 FPS
High: 2113 FPS
Avg: 2075 FPS
ES: 105 fps
SD: 28
(Surprisingly high velocity difference. Explains some of the vertical stringing I saw shooting this at 200 yards last year)

The remainder of the data here is from handloads.
1x case, resized with Redding full length sizer, #34 shell plate.
Cleaned with 4:1 ratio water:simple green for exactly 10 minutes, left to dry for 24 hours.
Rounds were .009" out of spec at the shoulder
Hornaday 40gr V-Max projectiles
Cartridge OAL set to match factory SS197SR.
CCI #400 small rifle primers
Reamed primer pockets w/ drill and SR primer pocket uniformer (not ideal)
Primers installed with RCBS hand primer using #34 shellholder
Measured powder digitally w/ RCBS750 and verified on gravity beam scale (RCBS 10-10)
Did NOT trim cases - all were within .010" of spec trim to length

5.1gr Longshot
Low: 2119 fps
High: 2211 fps
Avg: 2162 fps
ES: 92fps
SD: 44

NOTES: Did not cycle second round fired. Ejected OK but did not strip next round from magazine. Recoil was very weak. Otherwise OK with no pressure signs. Interesting that this load is right off the bat at starting velocity showing a higher velocity than SS197SR. I'm marking it up to a slower burning powder than factory.

5.2 Gr Longshot
Low: 2136
High: 2248
Avg: 2184 (22fps faster)
ES: 112fps (!!)
SD: 41

NOTES: Slightly reduced recoil, no pressure signs. Gained 22fps avg velocity over 5.1gr. No feed/extraction issues.

5.3gr Longshot
Low: 2126
High: 2225
Avg: 2190 (4fps faster)
ES: 99 fps
SD: 39

NOTES: *LOST* peak velocity over 5.2gr, but slightly tightened up on standard deviation and extreme spread. Only gained 4fps avg over 5.2gr. Normal level of recoil. No misfeeds or extraction problems. No pressure signs.

5.4gr Longshot
Low: 2150
High: 2283
Avg: 2216
ES: 133 fps (!!!)
SD: 47

NOTES: Alarmingly high extreme spread. Average FPS 26 higher than 5.3gr. There was a mark on the primers which matched a mark on the bolt face, primers were not set back, cratered, or flattened. Sharp recoil.

5.5gr Longshot
Low: 2225
High: 2339
Avg: 2274 (+58fps over 5.4gr)
ES: 114fps
SD: 43

NOTES: First round fired blew primer out of pocket. Upon removal of magazine, Casing was still in chamber. Primer missing (found under rifle). Bolt was thrown back out of battery and extractor had skipped off the rim. Inspected bolt and found no evidence of damage. Fired remaining 4 rounds without issue. Suspect a mis-throw on the powder charge of the first round. One primer was flattened, one blown out, remaining 3 rounded with no evidence of over pressure (no cratering, flattening, or raised primers).

Final note: I will continue with testing beyond this point once I get fixed dies from Redding. (The blown pocket was alarming but I'm shooting with a Kevlar barrier for a reason.)

Will post up pics of brass and targets in a bit.

 

[Trent]

Edit: I just reviewed the chronograph data and found that blown primer (which happened on shot #1 of string 9 today) was the highest velocity 40 gr shot of the day, at 2339 fps.

I have to swallow my pride and say that despite all of my precautions, this was definitely from a scale error that I didn't catch. Which is unnerving. By the 16th round I'd quit validating the charges on the beam scale because I hadn't caught any misthrows on the RCBS autodispenser and it was taking up so much extra time.

After the 15th round, the RCBS scale was set for 5.1gr and I was using the trickle button to get to .1 gr under the throw weight I wanted. Then I'd lightly tap the feed tube to get a couple flakes out to bring it up to the charge weight. Then I'd remove the tray and re-set on to the RCBS electronic scale to re-verify the weight. This was done with no exceptions. (I've never been this careful weighing powder before.)

The fact I still missed one tells me 2 things:

* Don't trust the electronic gadget when you MUST be accurate to .1 grain.
* Don't take shortcuts.

Will proceed with even more caution from this point and ONLY use the beam scale, period. This cartridge is proving incredibly dangerous to load. That round couldn't have been more than .2gr off of the mark. (At least, I've never caught my RCBS electronic scale more than .2gr off ever before, in 7 years of using it...)

Man, I wouldn't dump powder by volume in to these cases if you paid me to. These little cartridges are incredibly sensitive.

I'm a little nervous to go on, but my curiosity is going to make me do it.

I have a feeling I'll be picking up the pieces of a rifle at some point.

Before the Redding dies come back, I'm going to get a full-arm length Kevlar piece cut so I can wrap my firing arm in kevlar, in addition to the rifle-to-face kevlar panel I have. If the rifle DOES go I want as much protection as possible.

 

[Trent]

Reference factory load targets. (I don't shoot good when I'm shivering with gloves on, this is my worst 50 yard groups, EVER, with this rifle. So not really a good baseline for accuracy except where noted.)



SS195LF left, American Eagle right.


The left (below) is actually SS195, the right is a 10 shot group of American Eagle (was trying to get my chrony to pick up rounds before moving on to handloads.)

Note: the right 10 shot group was shot WITHOUT gloves on, and it's 1/2 the overall size of the 5 shot groups I had been shooting. Shows how big of a difference group size is when you have thick winter gloves on!!! This is why these targets can't really be used as an accuracy benchmark - too much human error.



Now that the world knows I shoot like crap when I'm worried about my chronograph, have thick winter gloves on, and my teeth are chattering.. moving on to the handloads, where things get even worse. No cheek weld. No shoulder weld whatsoever (kevlar interfered):

5.1gr Longshot


5.2gr Longshot left, 5.3gr longshot right:


5.4gr longshot left, 5.5gr longshot right:


Now on to primers;

5.1gr longshot:


5.2gr longshot (yes, the center one is flattened, I didn't see this earlier)


5.3gr longshot (the 4th one is flattened). There's also an odd arrow shaped mark appearing on primers starting at this level. I though this was from my bolt face, but I can't find a corresponding mark on my bolt face on further examination.


5.4gr longshot (the 4th and 5th are flattened more than the first three)


5.5gr longshot (1 blown, 1 incredibly flat, one sort of flat, 2 OK)


This was definitely an over pressure blowout. The primer cup was melted on the face of one side.



And the edge of it shows a crease - I'm assuming from where it blew out under very high velocity, and smacked the extractor or bolt face.


I have *never* seen a PS90 get this dirty before.


I don't have a pic handy but the cases are covered in carbon.

And I discovered one other MAJOR mistake I made when handling the cases to take pics - I didn't wipe the sizing lube off the cases.


There wasn't MUCH lube; I didn't need much when sizing them.

But, these cases have to "grip then stretch then blow back" so the sizing lube certainly interfered with this to some degree. Having any oil on the outside of the case HAS to interfere with the function of the dry film lube on the case. (I don't have any way of confirming or measuring this, obviously, so it's speculation.)

 

[Trent]

Some last thoughts before I let this thread rest until new dies arrive:

Since I'm starting out with this on UNPUBLISHED data, on a powder designed for shotguns (!), there's NOT a whole lot to go on.

The only source of data I found with decent notes and velocities for this powder was from Grant, on the FiveSeven forum. (If you ever read this, thanks Grant!)

However, his velocities are WAY different than mine (by about 300+ fps). So I have to assume he worked the load up using the 5.7x28mm FiveSeven pistol, not the PS90 rifle.

As you can see from the above photos I started encountering high-pressure signs WAY before he did (he made it to 6.2 grains before getting high pressure signs; I only made it to 5.5 grains).

The difference in this can be easily explained by barrel length, and burn rate. This powder is obviously a little SLOW to be using in the pistol. His velocity gains after 5.5-5.6 grains started getting erratic; meaning, unburnt powder was exiting the muzzle sometimes.

In the PS90 length barrel, this powder is still gaining strength (pressure) WELL down the bore. (It *is* a burn rate suitable for 12 gauge shotguns, after all). This will lead to some unpredictable results on the blowback action, which is timed differently.

This difference in burn rates of powders, means that it's really not possible to develop a load that is ideal for *both* the pistol and the rifle. What FN Herstal and Federal sells is truly a compromise.

As you can see by the data and research done so far, my starting load was pushing a faster velocity than the SS197SR cartridge, with the *same* bullet weight out of the PS90. (while Grant's load workup was pushing a lower velocity than the SS197SR out of the pistol.)

The basic synopsis of this leads to some interesting early conclusions;

A) finding a "better PS90 load than factory" is definitely a worthwhile cause.

B) It's highly unlikely I'll find an "awesome load" that works equally well in both pistol and rifle, since you have to compromise for it to work in both. (I'm positive that somewhere, FN technicians were pulling their hair out while developing the SSxxx rounds...)

C) It's highly likely that with enough different powder to trial, and enough testing on them, that I will find a load that is substantially more accurate and has better ballistics than the factory SS197SR load. (This one already shows better velocities, but the velocity range isn't stable enough to make Longshot suitable as a 200 yard round).

D) Reloading this cartridge is dangerous, and I plan on taking some risks that I don't advise anyone else to do. I have an expendable rifle AND kevlar on my side.

I DO NOT RECOMMEND USING ANY DATA IN THIS THREAD FOR THE FN FIVE-SEVEN HANDGUN, I AM ONLY TESTING IN THE PS90 RIFLE.

 

[Trent]

Because of the blown and flattened primers on 5.5gr of Longshot I'd recommend a starting load of 4.9gr instead of 5.1gr in the PS90 with a .1 grain increase increment for testing. That's 10% under the point I got pressure signs.

Decided to make five more tests before I ship the dies back to Redding. The dies are close enough to spec to get the PS90 to chamber them reliably, and my rifle is an older design with the "safety sear" which keeps it from firing out of battery. (Newer PS90's evidently LACK that additional sear... the reasons why and the danger this poses is an entirely different subject.)

The additional tests I'm going to run are precisely like the first, but with different primers.

The additional primers I have on hand that I will test with:

CCI Arsenal primers #44 (milspec)
Remington 6 1/2
Remington 7 1/2
Winchester SR
Federal 200

The only answer I want to get from this is "will Longshot extreme spread and standard deviation tighten up with different primers".

Because I'll be using Magnum small rifle primers in a couple cases, I'm backing off the load a little. I'll be starting at 4.6 grains (.5 under my previous start) for the Remington 7 1/2 and the CCI military primers (which are by some reports "hotter" than normal primers).

Stay tuned for more..

 

[Walkalong]

The only answer I want to get from this is "will Longshot extreme spread and standard deviation tighten up with different primers".

I doubt it. It doesn't take much to set off that small amount of powder in such a small case.

I would question whether Longshot is suited to the 5.7X28. It may be a powder position problem. I tried some Blue Dot in .22 Hornet years ago. Powder back was fine, but powder forward blew the heck out of a primer. Just thinking out loud. It would be easy to test.

I was using small pistol primers, and got good ES & SD numbers with True Blue and SR4756. I also tried 5744, but it was too bulky.

 

[Trent]

Were you using the pistol or the rifle?

I've read True Blue works great in the pistol but not so good in the rifle; popped off magazines, etc. Most of the reloading data I've seen on 5.7 has mainly been for pistol. I would imagine so people could "de-neuter" the civilian round. If the reports about True Blue popping magazines is right, that means the case is blowing back and ejecting before the bullet leaves the muzzle and pressures have dropped. (Maybe it's just a touch too "fast" for the rifle?)

(Either way I want to find out first hand later, when I put together a mail order for powder; can't find True blue around here).

On an unrelated (but sort of related) topic, I half suspect that FN isn't more supportive of reloaders due to that very reason. They're probably not wanting to risk one of their "flagship" products on litigation for being "armor piercing." The anti-gunners already took a really big swing at them in the past, doing their own armor piercing tests on IIA armor (without hard backing, the civilian rounds made it through, barely). The FN folks countered by doing *legitimate* testing with a properly mixed clay backing, and the rounds didn't penetrate.

The civilian ammo IS pretty neutered. I saw that first hand today launching the same projectiles as they use in SS197, and my starting load beat their factory load by 79 fps. The difference against Federal American Eagle was even more profound, with my starting load averaging 87 fps faster than the AE average!

I just finished loading a batch of 40 rounds, in 5 round groups from 4.6 to 5.3gr increments. I used ONLY the RCBS 10-10 scale this time and *every* load was dead on the money. With my vacation over and daylight still a rarity, I'm not sure when I'll be able to hit the range next time to test. It's a little too much equipment to set up and time spent doing record-keeping on velocity to fit it in over a lunch hour.

The thing I'm curious about with magnum primers, is this Longshot powder was very clearly burning pretty slow. The fact my pressure signs started .7 grains before grantness's old data in the FN FiveSeven pistol, indicates that the longer barrel is allowing the powder to reach it's potential (whereas, in the pistol, some is just blown out the end unburned.)

Using a magnum primer and lower loads (started .5 grain under my previous start), the magnum primer should accelerate that slow burn. I really do believe this will make the burn more consistent as instead of dragging out as the projectile moves down the barrel, it'll be more intense and hit the pressure peak earlier. It might cost some velocity since I'm going to have to use reduced charges, but I was already over the factory ammo by a fair margin anyway. I can afford to drop 4 tenths of a grain and still be ahead of the factory internal ballistics.

Anyway, sure is getting interesting. I've never really been this curious about how it's going to work before - usually my test loading is about "how small of a group will this shoot, versus how small of a group will this shoot."

Once I get some idea of how the different primers behave with this powder, I'll try to track down some Vihtavouri powder that's in the right burn range.

It sure adds an extra element of excitement knowing that if I goof up even a LITTLE bit, I blow up an expensive rifle.

(I've always kind of been an adrenaline junky though!)

 

[Walkalong]

AR 57. It uses the same mags as the PS90. Sold it.

 

[Trent]

Ahh. I've never used / examined one of those.

I assume it's blowback; Do those use the AR-15 buffer tube / extension? Or do they have a different recoil mechanism built in the upper? Do they have an anti-bounce device like the PS90 bolt?

Unless the bolt mass and spring weight/travel are identical to the PS90, it'd be hard to compare AR-57 and PS90 data apples to apples. The pressure curve would be different if the bolt mass or spring resistance were any different.

Sorry for all the questions, curious as to the inner workings.

(EDIT: Clarifying.. the pressure curve would be the same but the AR57 bolt weight and spring tension may provide more or less resistance to the blowback than the PS90. E.g. a load in one rifle that works OK may eject early, leak higher pressure gas, and pop the mag off in the other.)