How to measure best overall length

[davester00]

So how would one get figure out what OAL is best for his pistol?

What is the theory behind choosing OAL.

My setup:

Kimber TLE II RL .45

Magtech Large Pistol Primer R-P brass, Solo 1000 @ 4.2-4.8 grn, and a LSWC 200grn bullet from dardas.

Current OAL is 1.24"

Please help me find the best OAL for this setup.

Thank You,

David

Edited December 18, 2009 by davester00

[Merlin Orr]

1.22 - 1.25. Billions of factory rounds can't be to far off.

For wadcutters leave about a thumbnail thickness of the full diameter bullet protruding above the brass.

Edited December 18, 2009 by Merlin Orr

[Z32MadMan]

I chose a max and min oal and then I made a load for every 0.01" in between those two. I shot a 7 shot group of each load and chose the most accuarte.

[CocoBolo]

Best OAL Priority list.

1. Gun feeds and runs reliably.

2. Round makes desired power factor without excessive pressure signs.

3. Accuracy.

Most of the time this is fairly simple, but when you get into lead bullets each bullet mold has a slightly different profile and this is where it gets into trial and error fitting. SWC bullets just happen to be easier than round nose for length setting. Merlin's thumbnail approach is spot on for a start point. Then its a matter of checking fit in the gun and in the mags. A 45 SWC will be close to 1.260 (mold #38) but check for that thumbnail width above the rim of the brass.

I mostly work on the first two, get it to run reliably in the gun and make power factor. I have not found in the shooitng I do mostly USPSA that changing the OAL up or down has made any real difference in accuracy. This is probably because I always load as long as I can without contacting the rifeling, to keep pressures down.