Help Reading Pressure Signs (Rifle)

[kingmt]

What says to much pressure? I know if the bolt is hard to lift then you have went way past safe. I keep reading to watch for primer flattening but how much is to much? Is any flattening to much?

I just got done reading that when the primer shows its first signs of flattening to go 3% more & check for over pressure signs again.

I have been stopping as soon as I see the first signs of flattening but those are also the ones that show the first signs of tightening in groups.

I have only found one load so far that almost works without any flattening of the primer using Varget but it as some flyers. About every 5th round it throws one about 1in-1.5in out of the group. From what I have read I should go up in charge & I'm almost at my ideal load but that is when they start flatting the primers some.

 

[MEHavey]

Forget primers, period. They are way too variable in hardness these days to read pressure growth signs. Seriously, if primer edges actually go flat you're already beyond your limit (and you have no idea how far).

- Either get, read, stay below manual max's, or (better)...
- Get a chronograph, QuickLoad, and combine both with data from several updated manuals.

 

[243winxb]

See links here on pressure. http://www.thehighroad.org/showpost.php?p=5948418&postcount=5

 

[amlevin]

I agree with MEHavey. Forget primers. I recently shot a box of factory loaded ammo and the primers were so flat all that showed between the primer and case head was a fine line that looked like it was scribed with a sewing needle.

Stick with reliable reloading data and stay below published maximums.

On primers, I have shot some loads using Winchester primers and have them not only flat, but some signs of cratering around the firing pin. Loaded the SAME load, changing only the primer to CCI's, and all the pressure signs have gone away.

As stated, for a primer to be an accurate indication, it has to have some consistency in metal hardness and flow characteristics.

For working up loads I have started using "Load From A Disk software". Using actual case capacity from fire-formed brass and a chronograph has given me a lot more information on the internal ballistics than just "reading" a primer.

 

[918v]

You are right: if the bolt lift is hard all the way through, you have exceeded mex by a long shot.

Make a dummy round. Chamber it and fire. Lift the bolt slowly, paying attention how it feels. Then fire some factory ammo. Pay attention how the bolt feels. Then try your handloads. At the first sign of stickyness, back off the charge.

On Remington rifles, the bolt will start to get a bit sticky toward the top end of the lift when the pressure exceeds max. This is where I back off. I also look at primer appearance and casehead appearance. If the primer looks too flat: like it is one with the primer pocket, the load is too hot. If the casehead has ejector marks, the load is too hot. But the bolt will get sticky way before that point.

 

[PapaG]

Look also for a bright shiny ring ahead of the extractor groove.....sign of impending seperation

 

[cheygriz]

Over the last 45 years, I have come to rely primarily on case life.

If the primer pocket loosens after 1 or 2 loadings, IMHO, it's too hot. If you can reload it 4 or 5 timers before the pocket loosens, you're generally okay.

(Of course, you throw the case in the "round file" at the first sign of pocket loosening.)

Velocity is another indicator. If the reloading manual says a particular load should make 3000 FPS, and your load chronos 3500, there's a real problem somewhere.

Primers are not a good indicator in any case, but if you are going to use primer flattening as one of your indicators, be sure to use military Spec primers like Remington 9 1/2 or CCI #34

PapaG, I would think the bright shiny ring is usually more a sign of excessive headspace than pressure.

 

[amlevin]

Some also recommend taking a shell holder with you to the range. Use it as a gauge to check the case head after firing. If it shows any signs of being hard to insert into the shell holder pressure is too high.

 

[918v]

If the case has expanded so much that it won't fit in the shell holder, the primer will fall out of the primer pocket and you are at the brink of your rifle comming apart. There is no way you will be able to get the bolt open.

 

[cheygriz]

Bear in mind that we're talking clean chambers here.
Excessively dirty, or rusted chamber walls (like on some old military surplus clunkers) can cause hard bolt lift as well.

 

[kingmt]

I am no where near max published loads by the powder manufacture. The primers are just starting to show signs of being drove back by the bolt. Still round on the sides except for one load that I believe the powder to be hotter then it should be.

I fired a few rounds that I had to use a cleaning rod to tap the case to get them out. They pierced the primers & the primers looked like rivets after I removed them. These are put to the side to be pulled down.

So is a little flatting on the top of the primer OK?

I haven't had a box of factory ammo for a center fire for a long time so I have none to compare them to. I do remember Remington rounds getting stuck sometimes though.

 

[amlevin]

Another note:

Some people get carried away with their "reamers" and chamfer primer pockets a little much to make sure the primers seat easily. This can remove support for the primer and a lot of them will look like the "rivet" that was described. I see this a lot on discarded brass at the range.

 

[918v]

So is a little flatting on the top of the primer OK?

Yes. primers are supposed to flatten under pressure. Just make sure they retain their round edges. This is a normal looking 308 primer:

 

[gamestalker]

It's difficult to read pressures with the primers or the bolt. I can't tell how many times I've had problems lifting the bolt, and none of those were related to pressure problems. Factory and hand loaded have both presented a stiff bolt. Factory can be simply due to the fact that it is factory. And hand loaded rounds that have given me this sign were because of brass that was either from a different gun that I necked or brass that needed FL sizing because I had been necking it and it was due for a FL. Youur best guide to staying in the zone is to follow the data to the T working up nice and slow with special attention to how the brass looks around the shoulder and head. Now if you have a blown primer then it is safe to say your pressures are high. One more tip! Make sure when you charge to use a scale or you will be 100% guessing as to how much powder you are dropping.

 

[918v]

If factory rounds are making your bolt sticky, your rifle has a headspace issue.

If you use a neck-sized round from Rifle-A in Rifle-B and the bolt gets sticky, that is a self-induced malfunction unrelated to pressure.

We're talking about reading pressure signs for one rifle using new or FL sized brass. Once you start introducing other variables, then bolt lift goes out the window wchich is too bad because it is the earliest of the warning signals.

 

[kingmt]

When I was talking about factory ammo sticking I didn't mean the bolt would not lift just it need a few more seconds to cool down before the bolt would slide back for whatever reason. I'm probably also guilty of reaming to much. The ones that looked like rivets though there is no doubt they were over pressure. These may be the reason I'm just a little skidish now.

So the idea of increasing the charge until I start seeing signs on the primer then going up another 3% as my max load is this sound?

 

[918v]

I would go with bolt feel before primer appearance.

 

[kingmt]

I went to neck size the cases that I was testing & most were still tight enough to seat a bullet so I would assume that I am no where near max pressure & probably need more pressure to seal the chamber.

 

[243winxb]

I went to neck size the cases that I was testing & most were still tight enough to seat a bullet so I would assume that I am no where near max pressure & probably need more pressure to seal the chamber.

Light loads with slow powder & light bullets for caliber will do this. Standard factory Chambers.

 

[RDub]

Hey Guys

I’ve been following this thread with great interest, especially going back to the threads 243winxb linked to. A lot of valid information was offered by folks that have been doing this seriously for a long time. And all was consistent with discussions on this subject on other forums, so everyone is pretty much on the same page on this… Pretty much..

Well as I was reading along, a thought occurred to me.. I kept hearing the term ‘Published Data’…Well, what do you do if there isn’t any ‘Published Data’? I think someone brought this up.
What if you are shooting an obsolete cartridge and want to try some of the newer powder offerings, but the round isn’t being tested anymore? Do you just have to live with IMR4350 and H4831 and not venture out with newer products?
Or, what do you do if you are still shooting an Ackley Improved cartridge or, heaven forbid, another wildcat?
Now, someone might come up with the idea to call the powder manufacturer and ask them about cartridges they haven’t tested. Well, I’ve done this and they are VERY wary about offering information on non-tested areas. They didn’t used to be.. But they are now.
“Anything you say, can and will be used against you in a court of law”
Remember that phrase? That’s the motto lived by nowadays..

Well if you are shooting obsolete rounds and/or shooting wildcats, odds are you are an experienced handloader and understand all that has been discussed.. Well you had BETTER be anyway...

Here is a dilemma for example, with the .300 H&H..
What if a guy inherited grandpa’s ol’ .300 and wanted to start handloading for it because where this guy lives, no one has seen a factory round for it in a coon’s age, and wouldn’t know where to get any. But, the guy is savvy enough to know he can get components from on-line sources.
So he does that, along with some Reloading Guides. He also finds some old loading data handouts that have been hangin around the gun shop in town since the ‘70’s.
He wants to load 180gr bullets and IMR4831. He sees load data varying from 65.0grs to 73.0grs, all providing good velocities. So, he scratches his head and wonders, WHY all the different data showing roughly the same velocities?
Well the guy doesn’t have a chronograph yet, and being the cautious individual he is, decides to load 65.0 grs with the 180gr bullets.
Elk season comes around and all his buddies get him out huntin elk with his newly acquired rifle and his new rounds he assembled, which he is most proud of. He thinks he has some real butt-kickin rounds out there.

So what the guy is actually out in the field with is, a heavy .300 H&H rifle with .308 Winchester ballistics. Yeah, he will probably stumble upon an elk and kill it, but what sense does that make??

In MY rifle, an '80s vintage Winchester Mod 70 with a 24" bbl, the above load does indeed provide velocity similar to what a 180gr .308 Win factory load would provide.
After going about methodical load development, the kind similarly subscribed to here, I found that 72.0grs of IMR4831 with 180gr Nosler Partitions, W-W cases and primers provides ½ MOA accuracy at 2970fps at about 60°F ambient temperature, with no signs of high pressure. Case life is good… Has to be, Win does not make .300 H&H cases anymore..

This story and ones similar to it have been played out over decades of time in the shooting/hunting world in on way or another, for the good or the bad. I run into guys at the range and out in the field with knowledge and experience levels ranging from dismal to very good. How well one educates himself in this is up for grabs and it varies considerably. There are folks out there that really NEED to read some of this vital information, but I doubt they ever will.
So I appreciate those who spend the time and share knowledge gained by experience. All we can do is put it out there and hope it gets read and understood. The more education gets out there, the better for all of us.

 

[gamestalker]

I would not just forget primers. One of the first things I look at with my spent loads is the primer. I check for exceeive flattening and cratering. And a worse case would be a blown primer. I haven't found any inconsistency in primer hardness at all. If you are loading with the right primer for the application and not one of the types who uses small pistol in small rifle, large pistol in large rifle, and visa versa, the primers will help in determining signs. There isn't realy much else to look for to warn you of high pressure that isn't an almost too late sign. A really stiff bolt handle is a sign that would be cause to have my rifle closely inspected to make sure the chamber, lugs, or bolt face haven't been dangerously damaged. A ruptured case or head / neck separation is also a sign, but can be confused with brass that has been loaded for it's last time, unless it happens on a first or second loading cycle.

 

[kingmt]

The people with the knowledge all to often keep it to there self on these threads because they get dogged when they put the info out there. Most of the time the argument comes from someone that thinks they know what they are talking about but have no experience to back it up. I haven't read the thread that had the picture Win243 linked to but I did read the thread by Don(USSR) that was linked with that picture & there was a lot of great info there that got missed by the people that had there fingers in there ears going LA LA LA LA! THE BOOK SAYS! I have been fallowing the Powder manufacturers info & got some very hot loads at starting load.

If you want to know where the broke glass is in the field ask the kid with the cut foot not the ones that was playing around him.

 

[MEHavey]

In MY (300H&H?) rifle, an '80s vintage Winchester Mod 70 with a 24" bbl... After going about methodical load development, the kind similarly subscribed to here, I found that 72.0grs of IMR4831 with 180gr Nosler Partitions, W-W cases and primers provides ½ MOA accuracy at 2970fps

It would appear you developed this is a chronograph in one hand, and QuickLoad in the other. I say this because Sierra's 5th shows IMR4831 max'g out at 68.4gr, while Nosler's 6th shows 66.0gr being max. (I hope you also wrote the Lot# down too.)

Unfortunately, QL and Chrono are both relatively advanced tools which even experienced reloaders use only as artful reference points in addition to "the Books". So if that "...guy who inherited grandpa’s ol’ .300 [H&H] and wanted to start handloading for it..." doesn't have the background, books, or analytical/physical tools.... I'd advise him to "stick to the published manuals" even if it cost him that mid-range 308Win performance.

(After all, the Elk probably doesn't know how to run QuickLoad either.)

 

[RDub]

It would appear you developed this is a chronograph in one hand, and QuickLoad in the other. I say this because Sierra's 5th shows IMR4831 max'g out at 68.4gr, while Nosler's 6th shows 66.0gr being max. (I hope you also wrote the Lot# down too.)

Unfortunately, QL and Chrono are both relatively advanced tools which even experienced reloaders use only as artful reference points in addition to "the Books". So if that "...guy who inherited grandpa’s ol’ .300 [H&H] and wanted to start handloading for it..." doesn't have the background, books, or analytical/physical tools.... I'd advise him to "stick to the published manuals" even if it cost him that mid-range 308Win performance.

(After all, the Elk probably doesn't know how to run QuickLoad either.)

Hey I do hear what you're sayin..

Lyman #49 lists 69.0grs, Speer# 13 lists 70.0, and an official IMR Handloader's Guide lists 73.0grs as max.
Now IMR are the ones makin the dang powder and THEY say 73.0grs at 53500 CUP. Didn't IMR use a crusher to obtain the data? The rest of their data is pretty much consistent with most everyone else's data for other cartridges.
Now all the above is "Published Data" as well is it not?? So, what is one to do?
Lyman didn't show any pressure data.
Speer says their data does not exceed 54000 CUP.

Well, we do what we have learned to do as accomplished handloaders.

There is a reason for all the discrepancy. Differences is testing equipment, calibration, different chambers and barrels, different components, and whatever else you can think of.

If I were to find out for certain that a load I'm using exceeds 60,000 or 65,000 psi or whatever the SAAMI listed max pressure is for that cartridge, I would stop using it.
Technology is advancing all the time, and one day, maybe in my lifetime, there will be a more accurate way to measure chamber pressure. But until then, I'll rely on what I have learned.. And the books.

And you are most correct, Elk could care less about Quickload..

 

[MEHavey]

You have put your finger on one of those reloading situations fraught w/ peril.

IMR Site/300H&H:
180GrSIE SPBT/ IMR4831 / OAL 3.560" / 73.0C / 3,035fpsn / 53,500 CUP

And QL says IMR4831/73.0gr under a [email protected]" generates 79,000psi for 3,150fps.

(Y'all wonder why range safety officers get gray hair?)

I have to drop QL's IMR4831 rate/Ba by 10% to match the IMR's figures of 3,025fps for 65,000psi), and if the powder's actually burning at that lower rate it's still on the knife edge of absolute MAX. Even then there isn't a prayer of the shooter knowing where he is on that curve w/o a chronograph and at least a passing knowledge of internal ballistics.

And folks wonder why we call it the 'Art' of handloading.
Good thing that Elk can't spell....

:banghead: