Pressure signs [Archive] - Glock Talk

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chefcam81
10-03-2012, 16:47
Hello everybody, I'm a little rusty to reloading handgun ammo and need some input. Let me first start out by saying I don't shoot a Glock. I owned a 21 for a while, but it never grew on me. Fine weapons, but not for me. I shoot, among other things, a custom Delta Elite, which is my focus in this post. The reason I'm here at Glock Talk is because you guys have the most rabid 10mm fans and the most comprehensive 10mm forum anywhere!

So, I just got my pistol back last week from Rob Schauland at Alchemy Custom Weaponry after a 9 month wait. It is BUILT to the gills. Among other things, I had it fitted with a fully supported, ramped Storm Lake Precision match barrel & 26lb wolf spring.

With that in mind, I'm wondering what i need to be looking for as far as pressure goes? I took 3 loads out today and shot them over the chronograph. No ejection issues, flattened primers etc. However, I did notice some extractor marks on all of the brass (Starline.)
I'm not sure if it shows, but here's a pic
http://i1062.photobucket.com/albums/t488/chefcam81/D9400453-528F-4A9E-B5EF-AD83882DF1ED-3025-00000526D3A20EDB.jpg

The Chrono results were as follows:
All loads used 180 grain XTP seated @ 1.257" and Starline Brass
7.6 gn Power Pistol: Avg. 1,069fps, ES 53.02, SD 17.60

8.0gn Power Pistol: Avg. 1,086, ES 74, SD22.33

9.2gn IMR 800x: 1,105, ES 82.98, SD 26.03

Do these velocities sound right? I would like to get 1,200fps out of an 180gn bullet, but am not sure if that would be pushing it. This is a VERY EXPENSIVE pistol and I'd prefer it remain in 1 piece. What kind of MV do you guys get before signs of pressure begin to show?

Thank you kindly for any suggestions and advice. They are all greatly appreciated.

I figured I'd share a few Pics with you
http://i1062.photobucket.com/albums/t488/chefcam81/130.jpg


http://i1062.photobucket.com/albums/t488/chefcam81/141.jpg

noylj
10-05-2012, 23:19
Best way is to shoot same-weight factory loads and compare recoil, distance cases are ejected, and case appearance. Also, you can measure case head and case dimension about 1/4" above the extractor groove before and after firing. If either dimensional change is greater in your reloads than factory, you may be over factory pressure.
If you use CCI primers, you will need a higher pressure before the primer flattens than if shooting Remington.
Your extractor may have a burr. Your chamber may be very tight, causing difficult extraction not due to chamber pressure per se. Your spring may be light and gun is trying to open too soon and extractor is working against full pressure of load. Most likely cause--you're looking too close and your gun isn't broken-in yet.
Your loads appear to be about mid-range. Did you try starting with the starting load and working up?
At those velocities, you "shouldn't" be seeing any real pressure signs and you haven't described any either.
Your gun will show some REAL pressure signs before you blow up a 1911--unless you just wing it.
Try shooting about 200 loads right where you are and break in the gun and then worry about working up loads or trying to shoot for accuracy.

Kwesi
10-06-2012, 06:51
I load 180gr FMJ with Power Pistol & no over pressure signs with:

8.6 grains
1.250
Win LPP
Ave 1198. ( 1176 - 1216 )
EAA Witness Limited

Taterhead
10-06-2012, 11:30
You might consider purchasing some Buffalo Bore or Underwood Ammo for reference loads. They will be at or near the upper range for pressures. They both conveniently use Starline brass so there will be a basis for comparision to the yellow brass you are using. The primers in the photos are a little hard to see, but they do look a little flat. That might or might not be an indication of excessive pressures.

I don't load with Power Pistol, but the 800-X velocities seem consistent to what I have seen. The load is a half grain higher than the Hodgdon max, but a ways below Hornady book max. I personally think the Hornady max is a bit hot -- at least in my G20 -- since I did find symptoms of excessive pressure beginning at 9.1 grains. It is the only book load in my testing that has shown worrisome pressure symptoms (bulged & smiled brass with very flat primers). I have never been comfortable with the inconsistent results I have encountered with 800-X.

In my G20 4.6" barrel, 1200 fps with a 180 XTP is easily doable with Blue Dot or Accurate no. 9. Splitting the difference between Hornady maxes and Alliant/Accurate maxes gets past 1200 with no indications of excessive pressures. CCI 300 primers for both of those with regular Starline Brass. I seat to 1.255" with 180 XTPs.

By the way... that is a very nice Delta you have there!

EDIT: Underwood has a 180 gr 10mm offering specified for a Delta.

http://www.underwoodammo.com/deltaelite10mmauto180graingolddotjacketedhollowpointboxof50.aspx

fredj338
10-06-2012, 19:01
I wouldn't say your loads are "midrange", not hardly, but your bbl seems a bit slow, happens. Most 5" guns can get to 1200fps w/ full power loads using, LOngshot, BlueDot, AA#7 or AA#9, maybe PP. I don't see anything in the brass thas screams over pressure, so you could work up, but I would be fine getting a solid 1150ps w/ good accuracy. I never got really great accuracy w/ 800X & it meters like crap, so I moved on. Longshot is my current choice for full power 10mm loads. With the 175grWSTHP, 1250fps is good enough & seems to have room to spare.