Does a loose OAL not really affect .45 ACP accuracy?

[sbwaters]

Reloading .45 ACP with Hornady 200gr HAP bullets, uniform measured length of .582 inch each. Set Hornady Seating/Crimp die to achieve OAL 1.238" and crimp of .473. I know the ogive will be different for each, but I did not expect the OAL to range from 1.235" to 1.246".

Without adjusting the seating/crimp die, of the 50 rounds, the OAL and number of rounds with that OAL were:
1.235 - 6
1.236 - 3
1.237 - 2
1.238 - 13
1.239 - 2
1.240 - 0
1.241 - 0
1.242 - 1
1.243 - 0
1.244 - 6
1.245 - 9
1.246 - 7
1.247 - 1

Previous loads, where I have tried to adjust the OAL for each round to be 1.238" with 4.8gr Hodgdon TiteGroup, the chrono average velocity was 765fps, SD 7.3, and five shot 46 foot group from bench rest was 0.75". Sweet!

I have yet to chrono this batch and see if the different OAL affects accuracy. But I was interested in what lessons your experience could give me.

I would expect the base of the bullets to seat at different depths with the different ogive, but that would also have been the case where I seated bullets differently to get an OAL consistently 1.238 that chrono'd so well.

Am I going to discover that and OAL difference of +/- .006 is going to make no difference?

 

[CZ9shooter]

Probably.

Ever measure factory ammo?

If you want to tighten up your variance you will need sort your brass and use a seating plug that fits your bullet. I actually use a flat stem for XTPs.

 

[sbwaters]

I actually use a flat stem for XTPs.

Doh! I never would have thought of that!

 

[CZ9shooter]

A custom seating stem for the XTP/HAP would offer the best results, but a flat one is much, much better than using a standard round nose stem and jamming a truncated cone bullet into it. Plus, I can make them myself.