Any Handi Rifle Smiths Here

Mike, I'm spending the winter in my 5th wheel trailer out in the desert west of Tucson. So, I'm not able to look at the cartridge dimensions prints I have at home. Also, this laptop doesn't have a copy of the program “Quick Load” working on it. If I had it, I could calculate the peak chamber pressure with info on your load etc..

I did some research once on the minimum chamber pressure to stretch the cases back out and it is right in the same range as some cast bullet loads. 20,000+ psi to 30KPSI was the range if my fuzzy, old brain is anywhere near correct.

I went to the Dillon site and looked at the pic. of the gauge they sell. It looks like it may be a chamber cut in it to nominal headspace dimension for a 223. You could probably use the depth gauge end of your indicating calipers to measure the difference between the gauge end and the end of the ctg. case. You should be able to measure some change as the case shortens. I wouldn't set my sizer die down to hit the shell holder as it may add to the problem.

You might try comparing your cases and see how much they vary. Also how they compare to the minimum dimension that the gauge says is acceptable. See if you can correlate this to the cases that misfire. You could make the same test I did by using an unfired case with a fired primer in it. Just keep snapping the hammer on the same case and measuring H.S. and see if it's changing. You may already be so short that the firing pin can't hit it very hard already. I'd use a new case to try this test that isn't work hardened and already short.

Headspace is an actual dimension (length) that goes from the base end of the case to a datum line the bisects the case on the shoulder at a right angle to the center line. It's usually a diameter on the taper of the shoulder that is a convenient .375” etc. or so. It's not really the clearance between the case and the chamber. There are two H.S. dimensions given for each cartridge. One for the chamber drawing and one for the cartridge case. The typical tolerance to stay inside SAAMI specs. is usually a nominal length plus or minus .004” for commercial guns. But,it can vary. “GO” headspace gauges are usually ground to the nominal length.

Let us know if you take this any further and what you find.

I brought a stock AR carbine out with me in Nato chambering and am shooting the 55 gr. RCBS 22 bullet in it with 15 grs. of Rel. 7. It shoots pretty good once in a while. The twist is 9” and is waaaay too fast for this bullet. I'm getting 2120 fps. out of a 16” barrel and it works the action fine. Bullets are cast real hard of monotype metal to handle that fast twist without stripping. I never get any leading or plug up the gas system. When I get back home I'll make up a barrel in 12” twist or slower and a very short throat in 223 chamber where I can get the bullet to touch the rifling and still go through the magazine. I'm getting 1 1/2 to 2 MOA out of it now. It's fun to shoot. I bought it for a bug-out gun in case there's a really big calamity and I have to deal with any serious social problems that might arise.

Prepper? Tom