BTW, I should also note that while pulling the 7.8gr loads I realized I was a little bit heavy on the taper crimp... that may have played a part. I'll probably back the crimp off a bit from now on.

Quote from: tommac919 on November 12 2013 08:19:58 AM MST
<I started getting some undesirable case bulging at 7.6gr. I decided not to fire the 7.8gr loads.>

Just curious.. what were the expansion measurements??

7.4gr, 10 rounds
.4330
.4320
.4325
.4325
.4320
.4325
.4325
.4330
.4320
.4320

7.6gr, 10 rounds
.4335
.4325
.4325
.4325
.4335
.4325
.4330
.4325
.4330
.4340

I didn't measure the 7.0gr or 7.2gr loads.

Thanks for the tips, guys.

I made it out to the range to test out my latest AutoComp loads. Using once-fired brass out of my stock Glock barrel, I started getting some undesirable case bulging at 7.6gr. I decided not to fire the 7.8gr loads.

So my self-prescribed limit for once-fired brass in my factory barrel is gonna be 7.4gr. I'm coming to grips with the fact that I'm gonna need to invest in an aftermarket barrel.

Until then, I guess I'll work with what I've got. Next up I have some mild 7.0gr AutoComp loads with twice-fired brass.

I also scored a pound of Longshot and a couple hundred pieces of Starline brass over the past week, so I'm planning to do some experimenting. Thinking of pairing the Longshot with Winchester primers.

Howdy all,

'Newbie' here, first post on this forum. I'm new to 10mm, as I just purchased a brand new G20 Gen4 two weeks ago. Since I can handload/reload for only a few pennies more than .40S&W, I figured, why not! (I've been handloading for about 3 years - I've heard it said some people reload so they can shoot more, some people shoot so they can reload more. I'll let you guess which one I am : )

So far I've put just over 200 rounds through the G20, mostly factory loads so far, but I'm getting started on some load development with Winchester AutoComp (this powder has been AMAZING out of my Kimber 1911) and Federal LP Match primers. I loaded up 50 rounds last week (once-fired Armscor USA brass, Remington 180gr FMJ bullets @ 1.258" OAL, 7.0gr to 7.4 gr powder), and had good results at the range. No overpressure signs whatsoever. Unfortunately, I don't have a chronograph, nor do I have a place to use a chonograph as all my shooting is typically done at the local indoor range.

I loaded up some more last night, same powder and primers, but using once-fired Remington nickel plated brass. This time I loaded up 25 of the Rem 180gr FMJ and 25 180gr WIN JHP. Noticing that the FMJs are shorter than the JHPs, I reduced the OAL of the FMJs to about 1.248", which allowed me to seat the JHPs to 1.258" without adjusting the seating die. I'm ranging these in 0.2gr increments from 7.0gr to 7.8gr. 5 FMJs and 5 JHPs at each increment.

I'm basing my charge weights on the Hodgdon 10mm data, which lists 7.7gr max - BUT, I believe this data was developed with the Delta Elite in mind, and I'm fairly confident a G20 could easily handle the extra 0.1gr. I'm typically very careful when developing loads, always careful to closely inspect each piece of fired brass before moving up to the next increment.

Does anyone else here have any experience relaoding 10mm in a G20 using Winchester AutoComp? Any thoughts on my loads/methodology? Any chronograph data for my reference?

Also, to you G20 Gen4 owners out there: How does the factory recoil spring assembly stand up to the hotter loads? Am I OK with the factory assembly, or are there heavier Gen4 RSAs out there that I need to consider?

I don't have any desire at this point to load uber-hot loads for everyday target shooting - just want to do some rangefinding to determine safe and reliable upper and lower limits, then pick a load somewhere in between for range use.