View Full Version : Primer ?

08-11-2009, 07:57 PM
Can anyone help me with figuring out the safety of using large pistol primers in place of large rifle primers for .308 . I have cci 350 mag. l.p. primers and Rem. 2 1/2 l.p. primers. I am having a hard time finding large rifle primers in my area. I know that the only size difference is the thickness. I can't remember which is thicker and don't have any large rifles to check . I believe the rifles are thicker. I also believe the mag. large pistol burn rate is real close to the large rifle. Can I interchange these if my firing pin is long enough to strike the primer? Which primer should I use? Thanks in advance for the help. ISME

08-12-2009, 04:07 PM
Large rifle primers are taller and the cup is supposed to be thicker. The potential problem is that the thinner cup of a lp primer cannot contain the much higher working pressures of a rifle cartridge without piercing or blowing out.

I have never experimented with changing large primers, so I do not have any first hand experience, but from all that I have read it is not a particularly good idea.

I have switched sp and sr primers by mistake in a .223 Contender and have tried both intentionally in .357mag and .30carb Contender handgun loads. Two pierced sp primers in the rifle cases was enough of a warning. Since then, I have had no desire to use any pistol primers in rifle cases.

I had no problems at all with the sr primers in the revolver cases except for accuracy, and would not hesitate to use them again. (I would caution anyone wanting to try it that, as when switching any component, one should either back the charge off 10% or go back to the starting load and work back up.) With the powder/bullet combination I used, UNQ/158JHP, I got shotgun patterns when with spm primers I was getting 2" 50yd groups and did no further testing, but I see no reason why they couldn't be used, especially if you happened on an accurate combination. I have also tried sp primers in .30carb Contender loads - with certain powders and cast bullets they give better accuracy, but in general with most powders I tried they had little or no positive effect on the accuracy.

08-12-2009, 06:55 PM
if your pressures are low enough [like 35k] to warrant the lp's they can lower es's and standard deviation in some loads.
but in a regular 308 load i wouldn't even consider it.
in some revolver type applications,lr's are the normal primer just because of the higher pressures.

08-13-2009, 12:38 AM
I appreciate the help. I didn't want to try it until I checked. I guess I keep looking for more supplies . 3 1/2 more years and it might get better. In the meantime it gives me an excuse to keep going to the gun shops. haha!!!

Circuit Rider
08-15-2009, 04:19 PM
ISME, pm me, I have some lr primers I'll swap you. I live just east of K,town. Circuit Rider[smilie=s: