Interesting 45ACP fix

C

chris in va

New member
I have that weird Lee 160gr RF mold and tried for years to get it working in my CZ to no avail. The bullet is literally wider than it is long.:p

To my elation I recently found a 4# jug of Universal, as it was the powder I originally started with a few years ago and had been missing from the shelves until recently. For the heck of it I made about 50 with Universal and fired a few, waiting for it to jam as usual. Three mags later I knew something had changed!

Now why would a simple powder change suddenly cause my normally jamm-o-matics to feed smoothly? Nothing else has changed

 
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Just guessing here...but a somewhat educated one. The density of the powder caused a slight change in how your ammunition moved when picked up by the slide. This small change shifted how the cartridge aligns with the chamber. Perhaps someone with a degree in physics can explain the technical parts of the equation. I know my jam-o-matic was cured with a different bullet shape (last time I had one).
 
160 gr in a 45 acp is an odd choice. The slide timing was changed by the different burning rate of the powder. Thats my guess.
 
Without knowing which powders jammed, it's hard to be sure. Universal is slower than Bullseye, but a little faster than Unique, and it may just be that at the load level you chose it is providing the right impulse (force times time) to get the slide back far enough for it to have some runup before starting to strip the next round from the magazine. That's an element of the timing 243winxb was referring to. In general, a light bullet needs to run at a higher average pressure than a heavy bullet does to achieve a given total recoil impulse because it is in the barrel such a short time.
 
In general, a light bullet needs to run at a higher average pressure than a heavy bullet does to achieve a given total recoil impulse because it is in the barrel such a short time.
Click to expand...

I guess that tends to explain why light-for-caliber projectiles usually work best with faster-burning powders. Since Universal is close to the middle of the pistol powder burning rate continuum, I surmise that the powder you used in earlier, less reliable loads was somewhat slower burning. Is that the case? Does the 160 gr. projectile work reliably in other .45 automatic pistols, with previous reloads?
 
Have you done anything with the springs in your magazines? If not the slide is staying back a little longer allowing the spring to push the cartridge up higher against the magazine lips before the slide overrides the cartridge and jams.
 
No, nothing different with the gun. I was using 7625, 700x and maybe Bullseye, neither would get past ten rounds before jamming.

I really just got this mold a while back as a 'what if' experiment. It's really for 45 Colt but marginally useable in ACP. I really like how it feels just like a 9mm but still punches a fat hole in the target. If I can get these reliable, they'll get used in my matches.:p
 
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I'd guess that shooting other loads in your gun may have polished the feed ramp and made the short fat bullet feed easier. Or a slight change in OAL.
 
Mebbe you wuz holding yer tougue jes right wif the new loads?

Seriously, I'd go with Uncle Nick's explanation of "impulse". Semi-auto handguns work with pressure/time/mass of bolt. Getting one of these factors "out of spec." (in your case a very light for caliber bullet), will throw the feeding/chambering/cycling off. So, with a different powder perhaps you "re-aligned" the ratio?...
 
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