10mm and Winchester AutoComp powder

[danthaman]

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. 

[The_Shadow]

Hey Danthaman, Welcome to the forum.  Winchester AutoComp does generate more gas volume, hence more pressures.
You should be just fine on your loads as the Hodgdon book shows the pressure  with a 180 JHC with 7.7grains @ 1199 fps as 36,000psi.

LongShot is shown at higher velocities (9.5 grs. @ 1287 fps) with lower pressures for this same bullet at 34,600psi.

On GT, SDGlock23 tested some (post #49);http://www.glocktalk.com/forums/showthread.php?t=268411&page=2

Glock 20 Gen4 bone stock. Around 75-80 degrees out and humid.

180gr PD FMJ, 7.8gr AutoComp @ 1.250": 1,176 fps (51 fps ES)
200gr Rainier RNFP, 7.0gr Auto Comp @ 1.250": 1,088 fps (22 fps ES)
More or less my goal was to get a plinking 10mm round that isn't full powered yet is still more than typical .40 level loads. My target was a 180gr between 1100-1150 fps and a 200gr between 1050-1100 fps. I succeeded!

200gr Missouri Steeler, 7.0gr AutoComp @ 1.250" (1x PMC, Win LP): 1,147 fps (14 fps ES)
Nicely consistent but a fairly smokey too.

[u_daman]

Hello Danthaman

I am new to this forum, while browsing, It was funny and interesting that I had bumped into your question here. I have a G20 myself (with a lonewolf aftermarket barrel) and just recently tried Autocomp with COAL's of 1.250 & 1.260.  I then choreographed my reloads. For me this combo seemed smooth and accurate on my G20. I'd be happy to share my data and results if it helps... but first my disclaimer :-)

CAUTION: The loads or load data I disclose/publish  may or may not be appropriate for your gun or for the cartridge(s) and components mentioned. Due to typos, variations in guns and components, and the abilities and judgement of users of this data, I assume no liability for damage or injury resulting from using this information. DO NOT ATTEMPT TO DUPLICATE THE DESCRIBED LOADS without first working them up from a published safe starting level charge while watching for pressure signs. If you don't know how to do that please don't use this data, for your own safety and the safety of others.



Firearm - G20/w Lonewolf aftermarket drop in barrel
Bullet - Hornady - 180gr FMJ-Flat Point
primer - CCI-300 Large Pistol
Case - Starline
Powder - Autocomp 7.7gr
COAL - 1.250

Crono'ed
1167.0     -5.1
1168.0     -4.1
1163.0     -9.1
1189.0     16.9
1167.0     -5.1
1186.0     13.9
1183.0     10.9
1161.0    -11.1
1164.0     -8.1
1173.0      0.9

       High:   1189.0
        Low:   1161.0
       E.S.:     28.0
       Ave.:   1172.1
       S.D.:      9.7
        95%:     ±7.7

Firearm - G20/w Lonewolf aftermarket drop in barrel
Bullet - Hornady - 180gr FMJ-Flat Point
primer - CCI-300 Large Pistol
Case - Starline
Powder - Autocomp 7.7gr
COAL - 1.260

1165.0     12.4
1114.0    -38.6
1153.0      0.4
1138.0    -14.6
1136.0    -16.6
1133.0    -19.6
1181.0     28.4
1117.0    -35.6
1158.0      5.4
1098.0    -54.6
1286.0    133.4 f

       High:   1286.0
        Low:   1098.0
       E.S.:    188.0
       Ave.:   1152.6
       S.D.:     48.0
        95%:    ±35.5

Hope this helps... thx

[RMM]

Thanks for sharing!

[danthaman]

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.

[tommac919]

<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??

[danthaman]

<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.

[danthaman]

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.

[tommac919]

( there was a posting on this by taterhead ; http://10mm-firearms.com/reloading-10mm-ammo/load-data-warning/msg2025/#msg2025  )


I've noticed that .432-.4325 expansion is on the low loads for my gun/barrel...
Mid range loads for me follow this above thread at .433 ...
Hot loads run at a high end of .4335 using Blue Dot at book max listed loads with 180gr. Don't believe I've seen a .434 yet.

Yr hot loads only show one .434 ... maybe the case??  Most of the 7.6gr rounds were what I see as acceptible ( gun do differ tho )

thanks for the data.