45ACP case head variations?

[chris in va]

I bought a Frankfort Arsenal loading block for the 45acp. Most drop right in, but a couple didn't. All were PMC and had a case rim that measured .002" wider than the others.

Loaded thousands of 45's and just noticed this. Any reason for it?

 

[brickeyee]

Any reason for it?

Tolerance, or a lack of attention to the tolerances present.

I would check the loading block first.

If the holes are based on nominal case head diameter some cases may not fit.

Ammunition makers are usually more careful (but screw ups sometimes happen).

 

[243winxb]

45 acp rim diameter / SAAMI drawings with measurements.

Tolerance, .480" maximum to .470" minimum rim diameter. SAAMI > http://www.saami.org/PubResources/CC_Drawings/Pistol/45%20Automatic%20Match.pdf After many firings, the rim can grow in size. Sometimes this can cause a feeding problem, as the case head will not slide up the bolt face freely. Not a problem in revolvers, only autos.