LP vs LR primers in 45/70

[Sgt H]

I know a number of folks use LP primers in their 45/70 BP loads. Thought I would try some loads with LP primers with smokeless loads. I loaded up some rounds with my general purpose load of 24gr of 2400 under a Lyman 457193 and substituted a CCI 300 for the CCI 200 I normally use. Mainly wanted to see how the LP primers would work as I have a lot more of them than LR. Well, there was no appreciable difference that could be detected on the targets. Groups on paper at 100 printed the same place and if anything the groups fired with LP primers were a bit tighter. I adjusted the sights for 200 yards (based on LR fired loads) and again found no difference in POI. Well centered hits on 12" steel with both. No pierced primers or other problems though I would not use LP for T-Rex loads, but I have no use for those anyway. Hope this may be useful given the current component situation.

[Daekar]

Good to know! It makes sense, the gentler 45-70 loads are pretty low pressure. No unburned powder, huh?

[Sgt H]

Just as clean as with LR.

[HWooldridge]

LP should simply seat a bit deeper. I believe the cap cover metal is the same thickness.

[Midohhntr]

Good to know in case one or the other is unavailable

[Jedman]

A friend of mine who had a rifle chambered in 45-120 used large pistol primers all of the time with target loads.
I am not sure why he started using them but also said they worked great.

Jedman

[john.k]

I use LP primers because I have a 1976 Marlin 95,and it will not reliably ignite LR primers........its been like this since new .....weak hammer strike,or maybe the hammer is too light with the piece cut out for the spur extension......which fell off mine sometime in 1976.

[RustyReel]

Thanks for the tip guys, I have an IAB Sharps ( I know, I know) that has a 20% failure to fire rate on the first strike. Going to try the LP primer thing next time I get it out.

[Castaway]

A caution on using a LPP instead of a LRP. LPP’s seat deeper in the case and if the bolt face isn’t hardened sufficiently, eventually the primer can peen the metal around the firing pin hole in the shape of primer.

[Sgt H]

The point Castaway makes might be an issue in older guns with softer steel, even then it would likely take a large number of rounds to see any effect. True the LP primers seat a few thousands deeper in the pocket and get a bit longer run at the breech face when fired but I doubt the effect is significant. The primer is only forced against the breech by the power of it's own detonation, not by the operating pressure of the cartridge. At the point the pressure in the cartridge maxes out and forces the case head against the breech the primer is already there and is just reseated flush with the case head. As a test fire a primer in an empty case. The primer will back out of the case the approximate amount of the headspace in the rifle. Close inspection of the fired primer will likely not show any of the machining marks on the breech face. So the primer is not hitting the breech hard enough for it to show up on the primer cup. Now examine the primer of a round fired in a rifle that operates at 60,000 psi and you will see the marks on the primer. Just my $.02 FWIW.

[truckjohn]

I had issues with blowing pistol primers when I ran them in rifle cartridges. I did for the theory that their softer flash would cause less variation in the velocity. I'm not in the mood for gas cutting on my bolt face.

I think this is a case of "Test before you load up a whole pile." If it works for you, great, but watch for blown primers.

[PhilC]

Pretty good primer read on SKS board shows LP cup thickness is .020" VS .027" for LR - http://www.sksboards.com/smf/?topic=56422.0

[Lksdmachine]

Not sure if this logic applies but here goes.
44 magnum pressures and 45-70 chamber pressures can be very similar. I can’t see putting up my LPP supply and not run any 45-70’s anymore if I’m out of LR.
In the “who knows” future of primer supplies, I’m going to cautiously (of course) run what ever I can get my hands on to make a spark in my cartridges.
If I’m running reduced loads in my 45-70, I’ll run LP. I would do this to conserve my .308 use of LR supply.

.01 bargain advice.

[scattershot]

This shortage of components may have a silver lining, after all. Lots of experimenting to see what works and what can be substituted for what.