Buldged cases

B

Bob Thompson

New member
As I mentioned in the pistolcraft section I have been reloading .45 Super for my H&K full size for a while now using Starline 45 Super brass, Hornady 185 XTP's and Universal clays powder.I can only seem to reach about 1200 fps on my chronograph without buldging cases at the base. This is only slightly faster than some of the +p rounds I have seen. At least one magazine reached around 1300 fps with Power Pistol powder.The chamber of my HK seems a little loose but so do the rest of my 45 autos. Might this be the pressure curve deal inhearant with autoloading guns. Has anybody else experienced this with autos.Most handguns and rifles I have handloaded for seem to show other high pressure signs,ie, flattened primers,extractor marks,etc. long before buldging cases. Where am I going wrong. Thanks much, Bob
 
Is all of the brass from the same lot? Have you measured the thickness as compared to unfired? Perhaps you're experiencing excessive stretching of the case. Or maybe there is still pressure in the barrel during expansion and compression? Hope you understand what I'm attempting to enunciate.
 
In reply to fal308, yes all the Super 45 brass was from the same lot. The cases were discarded but the buldge was at least 30 to 40 thousants and OA length was about normal. The buldge was about the last 1/8 inch at the rim. I was thinking similar to you that expansion was still going on while slide started to extract the case, hence just the first part of the case being extracted,the 1/8 inch nearest the rim. If this is related to the pressure time curve perhaps a stiffer recoil spring would help retard extraction just as the Ace conversions do although Triton I belive tested their loads with a stock HK USP 45.I also have seen that most reloading from the gun magazines use a somewhat slower burning powder but not much slower. I belive my next small step would be slower powder but I just guessing. Does the swinging link in the barrel lockup of the Colt and their clones retard the rearward movement of the slide? I'm also thinking of buying a box of Tritons 45 Super just to see what happends. This reloading is fun...isn't it? Thanks again, Bob
 
Bob:

I wrote a long-winded reply to your question, but put it in the Glock Lead Bullet thread instead of here where it really belongs.

Enjoy!
 
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