I've never been one to put much stock in primers being terribly important but I decided to test two primers (Win Large Rifles and CCI-BR2) because of strange accuracy issues with my .38-72.  As an aside, I really hate .38s.  They give me endless fits.   

Anyway, I loaded 10 cases with each primer, newspaper over primer wads, 79 gr of Goex 2fg weighed to +/- 0.05 gr, compressed 0.1" and topped with a 0.030" fiber wad.  Bullet was 20:1, 320 gr, and paper patched.  No crimp.

Accuracy at 200 yds was terrible as per usual.  About 50-60% of the shots could fit under 1 MOA but the rest are doing well to hold the paper with most variation being vertical.   

The interesting part was that the WLR load shot 1488 fps with a miserable SD of 22.

The CCI-BR2 loads shot 1530 fps also with an SD of 22.

Obviously neither prodced "good" SDs, but what about the differences between those average velocities for two nonmagnum primers?  Is this typical?  Are CCIs generally so much higher?

Brent

Brent:

My guess is that much of the problem comes from those diapered bullets and the way you have to load them. You just can't get good initial resistance to the bullet movement. I think that with the larger bores the bullets have enough mass to resist movement enough for a good burn.

Have you tried it the pistol primer? They would, to my thinking, help with this problem. You may ulitmately need to come up with some sort of crimp to hold the bullet back

Glenn

Glenn,
I would like to try a taper crimp but such a die does not exist.  I tried a .38-55 die which I have, but it will not pass the shoulder.  I don't know if there is anyway I can grind it shorter so it might work.  I might give this a try.  I have tried crimping - such that it is - with the FL die, but that really is not very effective.   

I will try slower powder, Swiss 1f, because the Goex Exp 2f is really moving along a whole lot faster than I think it should.   

The primers?  Well, I have thought about that.  But this is an unbushed pin and it is backing out of the case a fair bit.  Enough to make opening the block difficult w/o dropping the hammer a second time, in which case the block drops easily and everything is fine.   

What else?  I could try more compression.  There is not a lot of compression on this load (0.1) but that would require even more powder and thus velocity and I am already working with a completely full case anyway.  I guess I could add a lot of wads.

Gert, groove diameter will not work with this throat.   

Did I ever tell you that I think .38s are haunted?

Brent

Brent, if your primers are cratering back into the firing pin hole, you probably need your block bushed. If the body of the primer is actually backing out of the pocket, then you almost certainly have excess headspace (by whatever amount of the extrusion). Possible bad news either way.
Good luck, Joe

I can't say anything about BP, never having tried it, but with smokeless, lab data shows that changing primers can turn some full power loads into proof loads. There's not a lot of data regarding this, but I've seen it reported in two separate tests. Interestingly, WLR produced the higher pressures; for your BP loads, it was the other way.