C.O.L. for .380

[clyde 72]

I plan to load 2.7 Universal with 100 gr cast boolits. Required c.o.l. by the recipe is .980. Loaded some dummy rounds to set the bollit seating die. Results over 6 dummy rounds are values from .974 to .980. Is this too much deviation or is it acceptable from a safety standpoint?

[Scharfschuetze]

Are the boolits from your mold or are they commercially cast?

When loading for a semi-auto pistol you'll need to compromise between rounds that fully chamber, rounds that function through the magazine and rounds that provide reliable functioning. I like to start with the longest overall length that will feed from the magazine and then see if they will fully chamber. If they meet both of those requirements, then I check for function. As long as your boolits are seated to always meet these three needs, then you should be good to go, even with a variance of .006" of COAL. I'm generally lucky and find a COAL that generally works well if it feeds through the magazine initially. Not always, but pretty often.

My procedure:

1. Load the rounds to the maximum COAL that you can load and then thumb through the magazine without hang ups.

2. Field strip the pistol and see if the rounds will then seat into the chamber without projecting past the breach or hood of the barrel.

3. If the above two steps work out or after adjusting for one or the other, then reassemble the pistol and go to the range to check for function.

As far as the variation in your dummy COAL, I'm not sure. With match jacketed bullets, even Sierra Matchkings, I've seen as much or more in bullet overall length and in rifles I use a Stony Point COAL comparetor length gauge that measures to the ogive of the bullet instead of the meplat to set my COAL. Cast bullets from the same mold should be much more uniform though. Check your seating plug and see if it has built up boolit lube in it that might be causing your discrepancy.

Good luck!