Home Forums Reloading Big Game Rifles Flattened primers

No, set your sizing die based on fired brass from that rifle, not factory rounds. It's entirely possible that rifle might have a little excess headspace, which is fine if you size for it accordingly.

Better and easier than the methods described above is to actually measure the shoulder setback. You can use the Hornady Case Comparator https://www.hornady.com/reloading/p...s/headspace-comparator-anvil-base-kit#!/ or make your own. Even a fired pistol case works in a pinch; a 40 S&W case should work for that Whelen, just make sure the case mouth is round.

To do this, set it up and zero the calipers on a fired case. Then when you measure a sized case, the caliper reading will be the headspace clearance you've induced by sizing. Back off the die until you're bumping the shoulders back only .002"-.004" for that rifle. You can bump even less in a bolt gun.

Zero:


Sized:

So I would say by just setting my SB die the way I have been doing it has been causing excessive head space. I did it as you guys explained and shot loads that were flattening before and today the primers looked perfect. Thank you for the help! Now I gotta pretty much start over with most all the loads I've tested but that's fine too.

Had the same problem loading for my brothers 35 whelen model 6. Stayed with about 54 grs. of rl15 and didn't worry about it.

Not to be an azzhole, but how would that be better than actually fitting the shell in the rifle that is shooting it? miles

tag

What I described is fitting the sized case to the rifle that will shoot it. The difference is measuring the shoulder setback so you actually know what it is and can achieve minimum but reliable setback, instead of this arbitrary "1/8 turn more" or "1/4 turn more" stuff that people are throwing out there. 1/4 turn is the difference between not enough and way too much setback. Even if you can end up at the perfect adjustment without measuring, what I described is a faster way to get there.

For what it's worth I have my head space issue resolved. Now I need to re test most all the loads I've tried that showed flattened primers. Some very accurate but flattened. Now that I figured out what is flattening every load I tested I might be in far better shape then I thought.

Not arguing that, as I do not know. But better I will continue my stance. The 1/4 turn, 1/8 turn is a measurement, as there are so many turns to the inch. miles

If you've chosen to remain ignorant, why did you ask? That statement gets a big facepalm for being clueless. Do you know how much of a turn in a sizing die is equal to .002"?

No, but I can calculate it if I choose. miles

Retest the accurate stuff if you think you were getting the velocity you wanted. They might actually prove to be more accurate that you thought.

Did you use the "1/4 turn" method?

Lol, no I just kept slowly turning my die a hair to a time until I bumped my shoulder enough to chamber. Not very scientific at all but it helped tremendously.

Well, I guess that's what I meant. I may try that even though I'm not showing flat primers. I'm currently only loading for one rifle.

Because of the way the brass springs back or deforms a 1/8 turn of the die later in the procedure won't necessarily produce the same sizing change as a 1/8 turn of the die earlier in the procedure. Whether you're measuring or going straight cut and try to fit, it's best to use very small increments until you're familiar with how your sizing set up interacts with your batch of brass.

My original recommendation was to fit to your chamber. Did not exactly spell it out like that, because I thought some here had mechanical ability. miles

Yes, but there may be someone less experienced reading this thread thinking he'll figure it by the thread pitch and be all set.

So was mine. Your insistence that guessing is better than knowing is baffling.

I kinda like fitting it to my chamber instead of measuring a lot. I can measure, but like the other way. I don't know where you get the guessing. If the bolt is hard to close, screw the die down a little. No guess. miles

You're guessing at what the headspace clearance is when you finally get it to fit. Could be .001", could be .015", you don't really know, especially if you're setting the die adjustment with just one piece of brass, instead of measuring a bunch of them. Measuring things is not hard for people with mechanical ability.

Measuring is better because it's a more accurate way to set minimum headspace.