Small Rifle Primers / .308 Win & 7.62x39

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Last Post 25 October 2023

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Wm Cook posted this 15 October 2023

Does anyone have any experience with handloading small rifle primed cases in .308 or 7.62x39?

Fast to medium burn rate rifle powders (4227-4895), typical weight cast bullets and modest velocities (2400-1800).

I’m down to a couple thousand LR and with all the stuff going on in the world I’m starting to think we might be one international incident away from me not seeing LR primers again in my lifetime. Thanks for your input, Bill.

A “Measured Response” is as effective as tongue lashing a stuck door.

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CBA Member

RicinYakima posted this 15 October 2023

Played with 30 American brass years ago, 30/30 with small primer pocket. Never could tell the difference, and it was only made for a couple of years. FWIW

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linoww posted this 16 October 2023

I've been using 30 American formed to 33-47, 32-40 and 35-40 Maynard and I can't tell an accuracy difference from my LR cases.Im using 4227 as well but at 1200-1400 fps..i did it because I also I have much more SR primers than LR. I also tried SR 7.62X39 brass (i think Hornady) and couldn't tell a difference from LR primers.

"if it was easy we'd let women do it" don't tell my wife I said that!

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CBA Member

Bud Hyett posted this 16 October 2023

Savage 1110S in .308 using R-P Basic brass (W-W Small Rifle Primers) would have hangfires about every twenty rounds.

Farm boy from Illinois, living in the magical Pacific Northwest

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CBA Member

lotech posted this 16 October 2023

When I began loadng the 7.62x39 cartridge more than thirty years ago, domestic cases that took small rifle primers were the only ones available. I used new Remington brass. I eventually got some of the Winchester brass with large primer pockets. Comparing the two, I found no difference, but I used far more cast bullets than jacketed.

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Wm Cook posted this 16 October 2023

George, what’s the case capacity is cartridges like 33-47, 32-40 and 35-40? How many grains of 4227 would you be using?

Bud’s caution about hang fires is a red flag but there’s something in my memory about National Match competition and the use of small rifle primers. No clue what powder that would be but I believe the course of fire was 600yds. I’m not an over the course shooter.

The neat thing about getting old is that you get so excited when you learn something that you already knew but had forgotten.

This thing about the ~50% of case capacity I’m using on my .308 has me baffled. How can the burn rate be consistent with the powder sloshing around. Sub Sonic & the use of pistol powders makes sense because that would be like an instant combustion with fast powders.

But from 4227 to 4895 the powder has to burn before the bullet leaves the muzzle and the position of the powder in the case and the type of primer (SR, SRM, LR, LRM) should effect change.

I don’t know enough to comment for SR .308 but brass is available including Lapua and LR primers are not. But with the cast capacity of the 7.62x39 it should work fine like lotech said. Provided you could find some 7.62x39 SR brass. If you know of any let me know.

I wonder what LRM primers would do to that “group” v “pattern” situation I was babbling about.

Thanks, Bill C.

A “Measured Response” is as effective as tongue lashing a stuck door.

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Ken Campbell Iowa posted this 16 October 2023

i converted 20 of srp 308 brass to 243 W ... couldn't tell the difference with cast and Unique ... ... quit after 20 shots ... still have 99, they are starting to look better and better ...

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Standard Member

Wm Cook posted this 16 October 2023

I think I found the reference to the SR and .308 competition.

A “Measured Response” is as effective as tongue lashing a stuck door.

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CBA Member

Mike H posted this 16 October 2023

Lapua Palma 308 small rifle cartridge cases are popular in Australia for match shooting,at the present time none are available.They are popular because they give longer case life.

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Standard Member

Wm Cook posted this 16 October 2023

Looks like 7.62x39 brass with SR primer is tough to find. I think Hornady makes limited runs.

I believe 6.5 Grendel can be resized to 7.62x39. Hornady, Nosler and Starline 6.5 Grendel brass is available to buy.

All this because I’m too tight to pop a grand for 5000 LR primers. Bill.

A “Measured Response” is as effective as tongue lashing a stuck door.

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CBA Member

Larry Gibson posted this 16 October 2023

In the 7.62x39 I've pressure/velocity tested with W-W cases/WLR primers and R-P cases with WSR primers using H4227 under 123 gr Winchester .310 bullets. Top end pressure loads (SAAMI @ 45k psi) showed it took 1/2 gr more 4227 in the R-P/WSR case to equal the pressure/velocity of the W-W/WLR case.

Have not run a similar comparison in 308W due to lack od SR primed cases. However, 7.62x54R, 7/65 Argie and 303 Brit Berdam cases converted to SR primers sows little difference if any with cast bullet loads using Bullseye, Unique, 2400 and 4895.

LMG

Concealment is not cover.........

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CBA Member

Paul Pollard posted this 16 October 2023

Starline shows 308 “match” brass on backorder, so at least they might be thinking of producing some. It uses small rifle primers. It might be a good long term plan.

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Standard Member

M1fuzz posted this 19 October 2023

I really wish the brass companies would just make cases that are SR. It can’t be that hard. Just make a smaller primer pocket I would think. With todays priming compounds and powders I really don’t think LR’s are necessary in all but the largest cases.

But, then again I could be wrong and usually am…..

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Standard Member

tomme boy posted this 19 October 2023

If running full pressure you have to have a firing pin that is matched to the SRP. Or you will blank primers.

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JimmyDee posted this 19 October 2023

I’m too tight to pop a grand for 5000 LR primers.

Wow. Are they really that expensive? Is there a LR shortage now?

Is the trend to small primers for everything?

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Standard Member

M1fuzz posted this 20 October 2023

There has hardly been a LR primer seen in the wild for approx. 3 years now….

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Standard Member

M1fuzz posted this 20 October 2023

Rifle? Never had an issue w/ semi auto pistols and a semi auto M1 Thompson sub gun clone a couple years ago when everyone was putting out tons of SP 45acp

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CBA Regional Director

MarkinEllensburg posted this 21 October 2023

If running full pressure you have to have a firing pin that is matched to the SRP. Or you will blank primers.

How can this be? What is the difference between a No. 1 in .223 and a No. 1 in .270? A hint for you, the barrel. The block and extractor are the same. The firing pin is contained within the block. Why would any other rifle platform be any different?

I can see why someone would conclude as you @tomme boy based on a test of 4 bolts and three firing pins. Thanks for the challenge, I was able to put to use the gauge pin set I purchased a few months ago. Results of my measurements are:

Milspec m16 bolt that came with one of my ar15 5.56 uppers firing pine hole in bolt .064" firing pin measured .06085"

M1903 I measured two bolts and one firing pin.

Bolt a .083"

Bolt b .082"

Firing pin .080 tapered to .076 right before tip.

Lastly a Ruger Model 77 in .338 Winchester Mag, bolt .079 and pin .078

The 1903 and Ruger both are no question manufactured and designed to be chambered for a LRP sized primer cartridge, that's not to say they couldn't be re-barrelled to a SRP cartridge. I find it interesting that the size difference between the two models is so large. The tolerance difference though is not surprising. The Ruger is not a battle rifle and doesn't require sloppy fitment to ensure functioning in all conditions. The sloppy tolerance of the m16/AR makes sense for the same reasons.

The M16/AR15 was first chambered for a SRP cartridge and has been used for many others since.

Of course I wouldn't be surprised if there are some manufacturers that produce more than one size of firing pin and use such as a marketing tactic. It is amazing the utter BS that gets passed onto consumers to lure them into thinking the something matters when it doesn't.

"But that true-coat.." Jerry Lundegaard

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tomme boy posted this 23 October 2023

If you follow the long range thing, 308w and 6.5creed pop primers in SRP brass. AR10 rifles are the worst ones for this. They make pins and bolts just for this. I guess I should say that it is more common in the AR10 than bolt actions.

I have had a bunch of rifles in 223 that blank primers. Once the bolt was bushed and the firing pins diameter was educed and reprofiled they never did it again. These were Savage(the worst for this), Rem700 rifles. Savage also has a problem that their bolt heads are dished from the polishing they get after machining. They use a ceramic media that dishes out the face. That was another reason to have the bolt head bushed is to true the face. Rem bolts just need bushed and a new profiled pin. But you have to be careful not to mess with the headspace. And thats why I lean to Savage because I can adjust it.

I had Gre-Tan do all of mine.

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CBA Regional Director

MarkinEllensburg posted this 23 October 2023

You've identified AR10's, Savages, and Remingtons as being susceptible to this. Is the issue more to do with sloppy tolerances in manufacturing than a difference in primer size? 5.56mm has a max pressure of 62,360 psi and .308 Win only 62,000 psi. Why would I not have issues with my AR15's and factory ammo given the sloppy tolerance I measured? Are factory 5.56 made with milspec primers? Do non milspec SRP have thinner cups than non milspec LRP?

I don't follow "the long range thing" maybe I am missing out. I have shot plenty of .223 with standard SRP and never have had primer issues, with AR15's. Always something to learn.

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MP1886 posted this 23 October 2023

Let us get bacl to SRP's. I have two cases that used them that give me problems. Those two are 6.5 Creedmoor and the 450 Bushmaster. With certain powders in both of them I get a lot of handfires. I do have both cases which take LRP's. With the same powders and same loads ZERO problems.

So here's something to think about. Most here are talking smaller cases and some of the variations are using cast bullets with fast pistol/shotgun powders. I believe the SRP has enough power to light those off. How about the larger cases that you're loading for hunting in very cold temperatures and to throw another caveat in the powder maybe be on the slower burning side. In this example I would much prefer the LRP's.

One last thing. Lapua 6.5 Grendel brass (perhaps others in that category size) have a smaller flash hole.

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Wm Cook posted this 24 October 2023

I know this thread is getting long in the tooth but since I have a personal interest in whether or not SR primers can be used in place of LR primers I'll add a bit.

1) A friend I met through the forum is sending me enough SR 308 pieces of brass that I can verify velocity to charge difference between LR and SR. Larry's work as indicated above included PSI which I do not have the capacity to provide. I will be able to compare velocity and to a limited degree references to accuracy between LR and SR primers. That's provided winter holds off for another month or so.

2) I have two twin Savage 10F's, one action has a 308 bolt face (.308 Winchester chamber) and the other has a bolt face for the .223 (.222 Remington chamber). The firing pins holes on both are virtually identical at .068. Ironically, before I measured the firing pin holes I ordered a .308 Palma decapping punch from Wilson. The decapping pins on my Wilson neck size dies for both the .222 Rem and the .308 Win are also identical at .071. So what if any difference the ".308 Palma decapping pin" is from what I already have on the bench is yet to be found.

3) Attached you'll find links to a three part article that I found on line. The articles were written by Lauri Holland and published by Target Shooters Magazine out of the UK. The article is specific to the .308 Palma SR case and the focus was on primer selection but it rolls out the history behind the US teams push to use the SR primer, the resistance it faced before finally being accepted. Blanking, hang fires and the why behind them are discussed. Personally I have to say that I was impressed by the rigid adherence to the experimental methods that were used. Made me look like a duffer.

How does it apply to cast shooters? My take away from the articles and from what you all said is that unless you are using slow powders with full, large case capacity and a primer with a soft cup (Benchrest primers and magnum primers have a hard cut) we should have no issue with fast to mid range rifle powders and small rifle primers with nominal capacity. The key point being the use of a primer with a hard cup and not to expect to light up case full of slow powder in a high capacity case. Thanks, Bill.

Target Shooter Magazine: Small Rifle Primer in .308 Palma by Lauri Holland

Part 1 click here

Part 2 click here

Part 3 click here

A “Measured Response” is as effective as tongue lashing a stuck door.

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MP1886 posted this 25 October 2023

Hey Bill in those articles there's a giant case prep that they aren't doing. Let me first explain what is wrong with weighing cases. Most everyone assumes the case that contains "the case chamber for lack of a better discription" is perfect and it's not. What they are missing is a difference in weight between case may most often be the extractor cut and rim trim cut. I won't mention the brass making company, but they pulled cases off the brass forming equipment at the point where the case was totally finished except for the extractor groove cut, head rim trim, and nomenclature stamped on the head of the case. What they found was the case weights were unbelievably consistent. They they pulled some finished cases out of the bin at the end of the line and weighed them and the variation was huge! What would that lead most people to think? That it has to be what I mentioned. Okay, why is this important? What they should do is measure the internal capacity of case. A friend of mine makes a tool for doing that and it uses alcohol because he can get all the alchohol our of the case better then water. So if you have the precise same amount of powder in each case and each case has the exact same volume then the pressure will be more consistent and so will the velocity. That's my take on it.

Now about what you said SRP may not be good for large cases with slow burning powder is true, but it happens with faster then slower burning powder in smaller cases. One examp I have is the 350 Winchester legend. BTW my 6.5 Creedmoor and 450 Bushmaster aren't exactly using slow powders. This is especially true of the 450 Bushmaster because it's a straight walled case. It's problem is large amount of powder that the SRP doesn't seem to light off well.

MP1886

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tomme boy posted this 25 October 2023

One other thing when using SRP in these cases is that you should be using the mag versions to help ignite the powder.

And yes you should never use CCI SRP in a 223 or 556 load. They are thinner and will blank before any other primer. They were originally made for the 22 Hornet that operates at a much lower (44Kpsi) pressure than 223 or anything that uses the srp. I had to switch to the CCI mag primer in my first Savage rifle to stop blanking primers till I got the bolt head fixed.

If you are going to run cast bullets then most of this does not pertain to you as the cast loads will probably not go over 44K psi.