308 Small Primer Brass - Ignition problem - Solution Found

[Acyr]

CCI 450's are a solid choice in Palma brass. Especially with VV powders. Wolf SRM's are also excellent with Varget as long as temps are 50+. But you need to weight sort them.

 

[Jeffrey Tooker]

On this forum and others there have been discussions of Wolf/Tula SRM primers
not firing, or not firing properly. Wolf SRM primers are quite particular about primer seating depth. If they are not seated all the way down, they will sometimes misfire.

Loading new Lapua brass (6 BR or 308 Palma) with Wolf SRM primers is a hard
fit. When I load new unprimed Lapua SRP brass for the first time I use a regular
reloading press. You need the leverage to seat the primer all the way home. You also need to check primer seating with your thumb to tell if the primer is properly seated. Placing the cartridge on a flat surface to see the primer is properly seated does not always work. You can feel things you can not see. After one or two firings primers can be seated with a hand primer seater. A few still take a strong squeeze to seat the primer. As always check the primer seating with your thumb every time.

Before Lapua made SRP 260 Rem. brass I made mine from Lapua 308 Palma brass.
I have shot that 260 Rem. brass with H 4350 on 35* mornings with no misfires. The rifle was large action Savage.

I have as others have stated above had misfires with Wolf SRM primers. It was a Panda action that I bought from someone else. I changed the firing pin spring, for a new one, and the problem went away. There are some very good National competitors who change firing pin springs every season.

IIRC in a discussion on this forum the difference between Wolf SR and SRM primers was discussed. SRM primers have a harder (thicker) cup. This is to allow for higher pressures. The ignition compound remains the same and in the same amount. If I am wrong in this conclusion will someone please correct me.

Jeffrey

 

[243winxb]

Bigger is better? Primers. LR VS SR

https://apps.dtic.mil/sti/citations/ADA599210

Abstract:
The U.S. Army Research Laboratory conducted a study to examine the effects of a small caliber 7.62-mm cartridge s spit-hole (flash hole) on the interior ballistic performance of the cartridge. The performance metrics evaluated were cartridge pressure and muzzle velocity. The laboratory incorporated its custom breech apparatus that measures primer pocket pressure, and used standard midcase pressure measurements and high-speed imaging to evaluate early projectile motion out of a custom-built short barrel gun.

4. Conclusion
A 7.62-mm primer force measurement breech design was proven out with standard M80 and
M80 ‟A” cartridges. A subsequent experiment evaluated the influence of reducing the spit-hole
area by 50.3% on primer pocket pressure and early motion. The experiments were successful in
proving the primer force breech’s efficacy in evaluating early time interior ballistics. Through
the course of the experiments the M80’s no. 34 primer produces very little initial force output.
This is contrary to what has been previously observed with the no. 41 primer used in the M855
cartridge. However, when the spit-hole area is reduced the force witnessed in the primer pocket
is about three times that of a no. 41 primer and 20 times that of a no. 34 primer with standard
spit-hole areas. Similar results were observed in fully loaded cartridges.
The reduction in spit-hole area caused a localized increase in primer cup pressure but did not
significantly affect the overall interior ballistic cycle. The decreased area resulted in the
propellant charge burning sooner and the projectile moving slightly earlier when compared to the
baseline M80, but not by a significant amount. The M80 ‟A” projectile motion occurred
significantly sooner when compared to both M80 variants due to its quicker burning propellant
formulation.

There is another study showing seating a bullet deeper, shorter col, helps powder burn better. Less case capacity. https://apps.dtic.mil/sti/citations/ADA341390

 

[DRNewcomb]

I've never had any problems with Lapua Palma brass when loaded with Varget and primed with Federal 205M primers.

 

[riflewoman]

Bigger is better? Primers. LR VS SR

https://apps.dtic.mil/sti/citations/ADA599210

Abstract:
The U.S. Army Research Laboratory conducted a study to examine the effects of a small caliber 7.62-mm cartridge s spit-hole (flash hole) on the interior ballistic performance of the cartridge. The performance metrics evaluated were cartridge pressure and muzzle velocity. The laboratory incorporated its custom breech apparatus that measures primer pocket pressure, and used standard midcase pressure measurements and high-speed imaging to evaluate early projectile motion out of a custom-built short barrel gun.

4. Conclusion
A 7.62-mm primer force measurement breech design was proven out with standard M80 and
M80 ‟A” cartridges. A subsequent experiment evaluated the influence of reducing the spit-hole
area by 50.3% on primer pocket pressure and early motion. The experiments were successful in
proving the primer force breech’s efficacy in evaluating early time interior ballistics. Through
the course of the experiments the M80’s no. 34 primer produces very little initial force output.
This is contrary to what has been previously observed with the no. 41 primer used in the M855
cartridge. However, when the spit-hole area is reduced the force witnessed in the primer pocket
is about three times that of a no. 41 primer and 20 times that of a no. 34 primer with standard
spit-hole areas. Similar results were observed in fully loaded cartridges.
The reduction in spit-hole area caused a localized increase in primer cup pressure but did not
significantly affect the overall interior ballistic cycle. The decreased area resulted in the
propellant charge burning sooner and the projectile moving slightly earlier when compared to the
baseline M80, but not by a significant amount. The M80 ‟A” projectile motion occurred
significantly sooner when compared to both M80 variants due to its quicker burning propellant
formulation.

There is another study showing seating a bullet deeper, shorter col, helps powder burn better. Less case capacity. https://apps.dtic.mil/sti/citations/ADA341390

video on point.

 

[Trevor60]

Evening

have you checked your firing pin protrusion?
Had similar problems with Wolf primers Lapua SP brass with my Borden.
i had a 2% FTF rate really irritating as the Wolfs were the best primers for ES/SD unsorted.
I switched to Fed 205m weight sorted during my initial issues no more FTF
Checked my firing pin and found it had min protrusion; adjust the firing pin and got better results with the the fed 205m ES 9 SD 3s
Never went back to the Wolfs to confirm if it corrected the FTFs
I use a RCBS bench mounted priming tool with crush
I shoot in Canada and have never experienced FTF do to weather have shot numerous times in 20's F temps -5 celcius.

Thanks
Trevor

 

[Scott Harris]

I've got a quandary to solve.

308 Win "practice rifle" - 1200 down the tube.
Lapua Palma Brass 5x fired, bumped .001"
Wolf SRM Primers
Varget
Lapua 167 Scenar Bullets jammed .015"

Here is the problem:

This thing is a hammer. Sometimes I wonder if it isn't tighter shooting than my F-open rifle, but I digress.

One to three out of 60 shots will fall low. I have always assumed they were because of me "it is a practice rifle for a reason." That is, until I was shooting with the Labradar the other day. Lo, and behold, the low shots are leaving 40 fps slower than the rest. I've always had mediocre ES during load development on this thing, but these are different. They recoil less, they sound funny.

I tried a couple of experiments already:

A little more primer crush up to .005" - Nope.
Use a different bolt and firing pin - Nope.
Change the charge upward/downward - Nope.
Tried different bullets (185 Jugg) - Nope.

So, I'm to the point where I think it is the primer, or the way I seat them. I'm using a 21st century hand primer. I've tried seating by feel alone, no difference. I've tried using the hard stop with various crush numbers to no avail.

I have CCI 450 primers on hand, and Federal 205's (not M's). Since small rifle primers seem to have evaporated from the world, which would you try first?

Thanks in advance,

Hi Keith,

The Wolf SRMs are your problem. They are extremely mild primers and just don't have enough ooomph to reliably ignite the 308 case in all conditions. Feel free to PM me for details, but your problem is 100% the primer. Switch to CCI 450s and your problem will go away.

 

[BradY]

Has anyone tried the 205m in varying temperatures? Wondering how well they go for ignition on those days with cold frosty mornings to warm sunny afternoons

 

[Alex Wheeler]

Wolf primers need to be hit harder than other primers. Increase your spring rate and be sure you have enough firing pin fall. Sounding different on those shots is a delayed ignition, your hearing the firing pin hit. Or switch to another primer IF you find one that shoots as well.

 

[J F Johannes]

Wolf primers need to be hit harder than other primers. Increase your spring rate and be sure you have enough firing pin fall. Sounding different on those shots is a delayed ignition, your hearing the firing pin hit. Or switch to another primer IF you find one that shoots as well.

Question for you, Alex. Can you hit a primer too hard and cause it to fail? TIA

Jim

 

[Alex Wheeler]

Jim, not in my testing. But I have not gone to the extreme, Im sure you could put a spring in so heavy you couldnt open the bolt and do some bad stuff. But in the case of any realistic amount of spring at least up to 32lb, no.

 

[J F Johannes]

Jim, not in my testing. But I have not gone to the extreme, Im sure you could put a spring in so heavy you couldnt open the bolt and do some bad stuff. But in the case of any realistic amount of spring at least up to 32lb, no.

What about too much firing pin protrusion? What is the recommended amount, so I can check my bolt?

Jim

 

[Alex Wheeler]

The only problem with too much protrusion is that it reduces effective pin fall. The primer stops the firing pin, so regardless of how much protrusion you have you will only have about .025-.030" when actually shooting. .050 or so is normal.

 

[Trevor60]

My pin protrusion when measured was .039

 

[J F Johannes]

Thanks for the info guys. I love this site! As I stated in post #14, all I did was deepen my primer pockets to .124 from .120 and the gun shot so much better. This Monday I will shoot a test side by side, uniformed vs. non-uniformed, everything else being the same. There is the possibility that the primer pockets were not square or distorted in some way also, I will have to check that, just not sure how yet. Maybe I am just getting .004 more pin fall? I will post back after the test. It's warming up here, so cold weather testing is not possible again till Fall or Winter.

Jim

 

[JAlfred]

What lot were your Wolf primers? There were issues with lot 9-09 and possibly others.

 

[Acyr]

Wolf primers need to be hit harder than other primers. Increase your spring rate and be sure you have enough firing pin fall. Sounding different on those shots is a delayed ignition, your hearing the firing pin hit. Or switch to another primer IF you find one that shoots as well.

Exactly. I run 28lb springs in my Bordens and Stillers, 32lb in my Savage Target actions with good success. Weighing to eliminate outliers in still recommended.

 

[dcali]

Has anyone tried the 205m in varying temperatures? Wondering how well they go for ignition on those days with cold frosty mornings to warm sunny afternoons

I have used 205s extensively in a wide range of temperatures (about 30-100), and a fair number of 205Ms. (I'm not convinced there's a difference, and have stopped using the Ms with no degradation in performance). They have always performed well. (This is in a .308, primarily)

 

[BradY]

I have used 205s extensively in a wide range of temperatures (about 30-100), and a fair number of 205Ms. (I'm not convinced there's a difference, and have stopped using the Ms with no degradation in performance). They have always performed well. (This is in a .308, primarily)

Thank you. I observed a match last year where shooters on a very cold morning were having problems with their ammo shooting poorly in cold weather but then fine again in the warmer afternoon. It’s been speculated the federal primers don’t perform well with swings in temp and I will test it by freezing rounds. Of course there is every chance their loads went out of tune due to the colder weather. One shooter using a faster propellant and large primers had no issue all day. All shooting 155 class bullets in 308.

 

[Sandstorm]

Anyone know the spring lbs to use in a Kelbley Panda F-class or Atlas tactical action.?