help with 308 Loads

[Wildalaska]

OK here is the scenario.

I want to duplicate the Hirtenberger match 308 load with the 190 grain match king. This is the load that my Swarovski scope is cammed for, and supposedly is optimized for the SSG.

Hitenberger gives a lot of info about the load. It is running 730m/s which translates out to about 2400 fps. OAL is 2.799. The powder they use is Bofors NP3, uunavialable in the US, but several powders are close to the burning rate and I chose RL 15 becasue it is available up here. The other 2 powders at the same buring rate that I can get up here are IMR4064 and maybe Vitavouri N140

Dont know what type of rifle they used to shoot to derive there velocity

So I will use Win 1x fired cases, 190 MKs and RL 15 and Fed 210M and work from there.

The sierra manual uses a 26 in bbl Savage 1-10, probaly close enough to the SSG. they list 38.8 grains to acheive 2400. They max it out at 40.4 for 2500 fps. Interestingly, N140 in the maanual requires 39.6 grains and maxes out at 41.3 for 2500 fps. IMR 4064 has data going up to 2600.

So I shot today, very sunny, wind blowing straight in my face. The chrony is a POS range chrony and probably is 40 fps error +/- although when I chronied my Swede it seemed dead on. Of course I dont have any Hirtenber factory ammo to chrony to see how it performs out of the SSG..

38.8 gave me an average of 2257 with an ES of 29.3. 39 grains gave me an average of 2262 with an ES of 51.6. These were fired wiith a warm, dirty barrel. Both grouped about 3/4 inch. Interestingly,l plugging in my specific numbers into Quickload predicts 2388 at 39.8 and 2400 at 39, difference of 123 fps and 138 respectively

Primers are not flat, recoil isnt bad, no noticeable case problems althio I did not measure expansion ring.

Now the issue is..

If I increase to 39.5 and then 40, it seems that at best I will achieve, at 40 will be per quickload 2455, if I take off 125 for the appaenrent difference btween observed velocities and Quickload predictions (and I have my bbl legnth and all other parmaeters plugged in) I am at 2325 which is consistent with the velocity steps I have been observing ( about 30fps per .5 grain)...if i run to 40.4 I would probably observe velocites of about 2350...I want to be at 2399...or as close as possible...

Now Quickload predicts with 41 I am at 2510, which based on observed velosities would put me close to where I want to be..OF COURSE, keeping in mind that I have no factory 190 grain Hirtenber to chrony out of an SSG to establish a benchmark....this however, while normal pressure per Quickload of 49406, the load is still HIGHER r than called for in the Sierra manual..also the pressure is a bit higher than the hirtenberger load.

So bottom line...do I keep working up with RL 15 even if I have to EXCEED the manual figures (of course keeping my eye on pressure), or should I just ditch it and move to IMR...interesting per quickload, IMR 4064 is giving higher pressures for the same velocity as is N140....eVEN imr 4320 AND n540 show predicted higher pressures to acheive the same velocity as RL15..

Keep in mind this is Alaska...cant really get Norma or some of the exotics.,....

WildconfusedAlaska

 

[pbhome71]

Of course I dont have any Hirtenber factory ammo to chrony to see how it performs out of the SSG..

This can be fixed. Century Arms happens to have this list on their web site at about $22.00/box of 20. I'm not sure how they ship this to Alaska, but it might be worthwhile. BTW, Century's catalog number is "AM1147"

Regarding pressure, I have a system called "Pressure Trace". You can use it to measure chamber pressure. I ordered one awhile back, but have not have time to uset it, yet. You can read about it here... http://www.swproducts.biz/PressureTrace.php I think the designer/owner's name is Jim (not sure though.) He is very nice, and will talk to you for hours, if you let him..

What I would do is to get some of the Hertenberger's ammo, chrony, and get pressure trace, and compare with your handload. It probably is over-kill, but might have been fun... We always need an excuse to buy a new toy, eh.. tool.

-Pat

 

[Wildalaska]

Hey thanks for the Hirtenberger tip, I will have to pay thru the nose but I can get some up here!

As to the pressure tool, if I got that SWMBO be whippin me butt

WildhenpeckedreloaderAlaska

 

[Wildalaska]

Bummer the Hirtenberger is 147 grain,

Helpppppppppppppppppppppppp!!!!


WildanyaustriansinthehouseAlaska?

 

[dakotasin]

just for your information, and not necessarily telling you what must be done...

if i have a rifle that seems to need more powder than the manual states, then i carefully work above the listed load. there are so many differences in rifles that it is hard for there to be one true, absolute max.

one scenario... if your velocity is lower than what the manual states, especially if it is a lot lower, then pressure is, too. variations in chamber sizes, seating depths, etc can all impact the variables.

i have a 308 that continued to get more accurate as the powder charge got stiffer, and never showed any pressure signs at all... the load i finally came up w/ exceeded the listed max in every manual i have - though it wasn't too awful far above what speer listed... but, trying to get the rifle to shoot at a given velocity is pretty tough. get the rifle to shoot where it is most accurate, and let the velocity be at whatever it wants to be...

out to 300 - 350 yards the point of impact will be close enough that you wouldn't know for sure that it was you, your rifle, or your load that might be off a little. beyond 350 yards or so, you really need to practice quite a bit, anyway... i would certainly not trust a scope's generic holdover reticles to tell me where to hold at for extended range shooting without a lot of practice to verify the come-ups - even if i could duplicate the load used to set the cams...

last thing... varget is an excellent powder in the 308. while my own guns have come out that varget generally loses to rl-15 velocity-wise in short barrels, but in longer barrels, varget wins the speed game. rl-15 and varget are extremely close in their data as well - can almost substitute grain for grain from one powder to the next...

 

[Black Snowman]

pbhome71, you've doomed me. An affordable pressure testing system? If I get one I'll want to start playing with wildcats . . . I'm so doomed. You . . . you I'll never get out of debt now!

 

[pbhome71]

Wildalaska,

Bummer the Hirtenberger is 147 grain,

Did you call them? The one of their web site said that it is 190gr "MATCH". Catalog number "AM1147". This was there the other day.

May be they ran out... What a bummer...

-Pat

 

[Frohickey]

I would go to the IMR4064 or other powder.
Since the load that you want with RL15 is over the spec, you really have to watch for the pressure signs. And with this batch of RL15, and with the current weather condition, you are fine in the pressure department. BUT YOU MIGHT NOT BE AS LUCKY IN THE NEXT BATCH OF RL15.

Have you tried Varget?

 

[Mark whiz]

Wildalaska,

Most all of the Hirtenberger I've ever seen was indeed 147gr NATO ammo.................but it's REAL good stuff.

For the Record, If you want to load to NATO Specs for that scope, they are:

147 (150)gr FMJ 2750fps
168gr FMJ or BTHP 2550fps

My Springfield rangefinding scope is based on the mil-spec 168gr round, hopefully your Swarovsky is too.

BTW ........... I've had great luck using RL-15 with 147 - 150gr FMJs. My best 150gr M1A loads are either with RL-15 or Win748.

 

[Wildalaska]

BUT YOU MIGHT NOT BE AS LUCKY IN THE NEXT BATCH OF RL15.

One of the reasons I got RL15 is that all the lots are the same up here...I can get a 5 pound jug thats the same lot as what I got, and that will last me two yrears....

I havent tried Varget, only becasue it appears almost interchangeable with the RL 15...

I guess the issue is is it gonna hurt to go 1 grain over the puiblished max in one manual..

For the Record, If you want to load to NATO Specs for that scope, they are:

My scope is cammed for the Hirtenberger match round whcih is a 190.

WildtoohottoreloadtonightAlaska

 

[dan newberry]

Speer number 12 lists 44 grains of RL15 as max with their 190 grain match bullet.

Admittedly that would be a pretty warm load. Speer shows it making 2561 fps from a 22" Remington 700 barrel.

I'll give you a link to my website where you can read about OCW load development. That should allow you to find the correct charge weight that will remain accurate in spite of minor pressure changes such as odd brass cases, odd primers, slight over/under charge of powder, weather induced pressure changes, etc.

www.clik.to/optimalchargeweight

If the Hirtenberger recipe is doing well in various rifles, they've likely identified an optimal charge weight (OCW).

RL15 is made in Sweden by Bofors; it would be highly unlikely to find a lot of difference in RL15 and the closest burning Bofors powder.

Pull apart one of the Hirtenberger shells if you have any left. Weigh the charge and inspect the powder that is in there. Use a magnifying glass, and use your nose. Burn a bit in an ash tray (wear safety glasses, yes, but it won't "explode."). Compare the burned smell of the Hirtenberger powder to the RL15. Then compare the weights of equal volumes; another clue that you're dealing with the same animal.

If you determine that the factory ammo is using a powder near identical to RL15 (and it may actually be the very RL15 recipe for that matter) then you should be able to carefully and safely work up to whatever charge was in that cartridge PROVIDED that you consult a reputable loading manual to ensure that the target charge is safe.

The only time you'll find a factory using a "propreitary powder" is when they get a screamin' deal on a train load of off rate powder. They'll find a way to make it work in many cases. More often than not, factory ammo will be put together with commonly available powders. They'll tell you their powders are "propreitary" but that's smoke and mirrors to stop you from trying to duplicate their ammo. So when you hear "propreitary powder" think: "goober-doofed powder lot; sold at a discount." Such occurrences are not common.

I think you're going to find that somewhere around 42.5 to 43 grains of RL15 will make the desired velocity with your 190's. If you become interested in doing an OCW work-up we can discuss the five charge weights to test...

Dan

 

[Wildalaska]

RL15 is made in Sweden by Bofors; it would be highly unlikely to find a lot of difference in RL15 and the closest burning Bofors powder.

Just got an email form a guy in Sweden says they are very very similar.

The more narrow issue is that to obtain my target velocity, all lack of pressure signs being equal, is .4 grains over a listed max gonna hurt..I would still be below that Speer max by several grains...

Wish I had some Hirty to open up!

I am thinking I will shoot 39.5, 40, 40.5 and 41 looking for pressure signs with the chron....what would your weight suggestions be Dan curious?

WildthisdisfunAlaska

 

[Wildalaska]

Interesting, I found out that Hirtenberger loads 42 grains of Bofors RP3 in the load in question...so Dan you8r prediction was correct!

What five charge weights would you suggest?

WildmorenadmoreinterestingAlaska

 

[dan newberry]

Since Hirtenberger stuff is using 42 grains of the "whatever" powder, and you have it on good authority (the Speer number 12) that 42 grains is safe...

then just work up to 42.3 grains in .3 grain increments. Once you have shown that 42.3 grains is safe, then shoot a few OCW "bracket groups."

That means to fire three shots into each group thus: One shot 41.7 grains, one shot 42.0 grains, and one shot 42.3 grains. If 42.0 grains is indeed the OCW (and we do often find that venerable factory recipes are optimal charge weight loads) you will see the 41.7 and 42.3 grain shots land right with the 42.0 grain shot in the three shot group. If that's the case you're done; just stay with the 42 grains.

If you note that either the 41.7 or the 42.3 grain shot wants to move away from the other two shots, it's time to do a true OCW round robin work up.

You really can't go for a target velocity and be ensured of optimal accuracy and recipe resilience; however, if the Hirtenberger stuff is good enough that Swarovski made a scope to follow it I think it's safe to assume that the Hirty recipe is very stable; what I call an OCW recipe. Extrapolating on that, if the powder is RL15 or something very much like it, you're going to find that same velocity with the OCW of RL15. The only difference might come with the brass you're using. If the Hirty brass is thicker (likely) than Winchester or Lapua you may have to increase the 42.0 grain charge to 42.3 or even 42.6 to get the same pressure/velocity.

Work carefully and all will be well.

If you choose to do a round robin OCW test use 41.8, 42.1, 42.4, 42.7, and 43.0 grains. Fire these charges in round robin fashion (see my website for specific instructions) each at its own target. Stop if you encounter pressure signs, of course.

Keep me informed. That 190 grain recipe sounds good...

Dan

 

[Biff]

Wild-

I've found that .308 cases vary quite a bit in capacity. Winchester tends to be a bit roomier, Remington can be closer to Military. This may also be a reason for variance between manuals.

I really like RL15 for the .223, as it is very consistant. I did notice that it likes higher loading density, i.e. full case with no air gaps, but not a compressed charge.

My Hodgdon manual gives 42 grains as max for RL15 with a 190 grain bullet, velocity 2515, CUP 47,500.

Alliant only goes as high as a Speer 180 spitzer, but gives a max load of 44 grains RL15, velocity 2645, pressure is 57,500 PSI (not CUP).

 

[Wildalaska]

Fun!

Dan I see you are using three grain increments...since I am at 39, what would you think of starting at 39.8, then go 40.1, 40.4, 40.7 etc...in oyther words work up AND ocw at the same time.

Wildgonna have to shootsundayAlaska

 

[dan newberry]

WildAlaska,

I think that's a decent idea. But I don't think you'll need three rounds each of the lower charges. I would just fire one shot at 40 grains, another at 40.3 grains, a third at 40.6 grains... go on with one shot each until you get to 41.5 and then get started on the round robin testing, looking for a common point of impact with the 41.8 through 43.0 grain charges. Since you always begin low and work up with the OCW test you are covered for pressure limits if you pay close attention to the signs.

Let us know how things go...

Dan

 

[Wildalaska]

Im case preppin as we speak!

Trimming to 2.005!

WildmakingturkeyandtofusouptooAlaska