Range Repot: 10mm; 180 JHP; AA#7

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Nick_C_S

New member
So I loaded up some rounds to work up some 180 JHP's, using AA#7.

Charge weights: 11.2gn; 11.4gn; 11.6gn; & 11.8gn (Speer #14 and Hornady 9th both max at 12.0gn). All charges hand weighed.

Bullet: Everglades 180gn JHP: OAL 1.255" +.000 / -.005

Primer: CCI 300

Brass: Mixed. HPR, PPU, & FC (nickel)

Guns: Glock 29sf (3.7" bbl), Lone Wolf barrel; & Glock 20sf (4.6" bbl), Lone Wolf barrel; aftermarket Titanium recoil spring.

Purpose: High recoil range practice; emulating full power defense rounds.

10 round strings from each gun.

Results:

11.2gn
G29 - 1142 fps avg; 25.49 SD
G20 - 1173 fps avg; 15.55 SD +31 fps over G29

11.4gn
G29 - 1155 fps avg; 23.62 SD
G20 - 1184 fps avg; 19.23 SD +29 fps over G29

11.6gn
G29 - 1165 fps avg; 28.82 SD
G20 - 1206 fps avg; 16.18 SD +41 fps over G29

11.8gn
G29 - 1188 fps avg; 38.02 SD
G20 - 1230 fps avg; 29.39 SD +42 fps over G29


Comments:
I shouldn't have used mixed brass. Subsequent 10mm Auto workups will be with all Starline brass. Standard Deviations did not impress me much. I chronograph freehand (not from a rest), so that probably gives me some additional SD. But at least the SD's showed an upward trend as charges increased; which is more or less to be expected. Velocities increased in a linear enough fashion as to not cause concern. No otherwise signs of overpressure either.

The 11.8gn charge had Extreme Spreads over 100 fps in both guns. In general, it did not appear that there was any kind of a "sweet spot" to be found in this charge range. If it existed, it was obscured by variables. Velocity results slightly exceeded published results from both Speer and Hornady (they both use a 5" test barrel). Not that I dwell on comparing my results with published results much. Just a noteworthy reference point.

Conclusion: I just shot these today, so I'm not sure what my next step will be just yet. I'm good with the 1200 fps neighborhood that was achieved; but I wish they did so with more consistency. Velocity is fine; consistency is poor. I was hoping for SD's to be in the 15 to 20 range more frequently from the Glock 29 especially.

My initial thoughts moving forward are to try 11.7, 11.8, & 11.9gns - this time using all Starline brass. If for no other reason, just to gather more data. Maybe they'll settle down some next time. Who knows.
 
10mm references are always welcome, thanks!

My new clamp-on-barrel-chrono arrived yesterday and I'll finally be able to measure my first 10mm loads on Bullseye (lol). Also being fired out of a G29. Will be interesting if Bullseye delivers better consistency at those velocities. My brass will be Starline, so lets see how your next batch turns out.
 
I found a very similar trend with my loads when I used #7 and the heavier bullets. I switched to #9 for the 180gr and up and things came together for me so I stuck with it. I still DO use the #7 but for the lighter 155 thru 170'ish grain weights. It seemed to do better in that range.
 
Will be interesting if Bullseye delivers better consistency at those velocities.
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Well, I would expect Bullseye to run more consistently. But I would be very concerned if "those velocities" (approaching 1200 fps) are being attempted with B'eye. Off the top of my head, I would expect max pressures with B'eye to deliver in the 1050 fps range.

I switched to #9 for the 180gr and up and things came together for me so I stuck with it.
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I tend to be a fast powder loader. And I don't have any AA9. If I did, I'd only turn to AA9 if I had the new Glock 40 (6" bbl) and was pushing 200gn bullets. That's just my loading style. Getting back to the AA7: These were the first 80 rounds of 10mm Auto I've ever loaded with it. I consider the data I have to be minimal. I won't be so quick to give up on AA7; besides, If I do, I'll move to Power Pistol. (A full workup using Power Pistol is most likely forthcoming - regardless of the outcome with AA7.)
 
I don't have the load data handy, but my best load was a close to Hornady's max load of AA9 under a 180gr XTP and it was right at 1300fps with an extreme spread right at 10 fps from my Glock 20.
 
I find it interesting that across the board, SDs are better with the G20 all be it pretty close with one. Don't feed me to the wolves for this, but Ibam not very familiar with Glock. Does the G20 have a longer bbl? I assume so because of the increase in velocity. And if so, perhaps this load likes a longer bbl?

Also, why the emphasis on using all 1 headstamp brass? What do you suspect the mixed brass caused?
 
Does the G20 have a longer bbl?
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Yes, the G29 has a 3.7" bbl; and the G20 has a 4.6" bbl. It would seem that the rounds tend to "settle down" with the longer barrel, delivering better consistency.

Also, why the emphasis on using all 1 headstamp brass?
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Mostly to eliminate it as a variable.

What do you suspect the mixed brass caused?
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I don't actually think it caused anything; but it was something of a rookie mistake. It's just better to do load workups with as few variables as possible. That way, any changes can be attributed to the load itself. Scientific method, I guess it's called.

I already loaded the next round of this workup. They're 11.7, 11.8, 11.9, & 12.0gns. Now normally when I do workups that are into double-digit grainage, I find it pointless to go in 0.1gn increments. But I decided to do so this time because I'm just kind of hoping maybe I'll find something. And yes, I used all Starline brass this time. After this next set of chrono results, I'll most likely pick a load level, call it 'set' and move on to another project. Remember, the purpose of this round is for recoil practice - particularly with the G29 - they don't actually need to run with outstanding consistency.


I plan on getting to the range Thursday or Friday to get these things chronographed. I'll post the results in this thread.
 
Ha ha.... yeah ok I sometimes have to step back and ask myself dude. Really? Geez. I just re-read your original post and right there, in plain view now doubt, you state the bbl lengths of both Glocks. Thats a little embarrassing. Lol. Really. I am not always that short minded. I look forward to your next results.
 
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