Gas Gun reloads


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REL1203
August 4, 2010, 02:42 PM
If I am reloading for a Gas Gun, should the loads be slightly toned down?

Reason I ask is I just loaded up some 308 for my DPMS SASS. I made a few batches, all using VARGET powder and am now starting to think they might be to hot for my Semi Auto SASS.

169 SMK
43.0
43.5
43.9

175 SMK
43.0
43.5
43.9 (this i particularly think might be to hot).

I made just 5 of each, should I dump the highest loads and make a batch of 42.5's?

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rcmodel
August 4, 2010, 02:49 PM
Both your loads are well below maximum.

Hodgdon list a Varget starting load with a 165 grain Hornady as 42.0. Max is 46.0 grains Compressed.

They show the 175 SMK with a 42.0 Starting load, and a 45.0 Compressed load as MAX.

But, yes, you should always start with the recommended starting load and work up from there.

rc

REL1203
August 4, 2010, 03:01 PM
Hodgdon is where I got most I my numbers to start with I believe (I also have the Hornady, Speer and Sierra Manual), but didn't know if Gas Guns required anything special since I haven't reloaded for it yet.

Bovice
August 4, 2010, 03:04 PM
i've got a gas gun that fires at +P pressures and a heck of a muzzle flash.

rcmodel
August 4, 2010, 03:07 PM
No special provisions for gas guns, other then using a powder of the correct burn rate.
Varget is one that is correct.

Your AR-10 is fully capable of handling any pressure you will find in any reloading manual.

Just stay away from the fastest or slowest burning powders and you will be fine.

rc

EMC45
August 4, 2010, 03:21 PM
What kind of brass are you using? Is it military?

SlamFire1
August 4, 2010, 03:40 PM
Yes, loads for gas guns should be toned down. 308 Nato loads are loaded to 50,000 psia, commercial is 60,000.

Use a chronograph to develop your loads.

For my gas guns I keep my 168s to between 2575 fps and 2625 fps in a M1a.

White Box match pushed a 174 FMJBT to 2550 fps. So I keep my 175 Sierra bullets under 2600 fps.

My lot of Varget gave me case head separations in this M1a, so I figure I have a slow lot.

M1A Douglas 1:10" Barrel


168 Hornady Match 41.0 grs Varget wtd Lot 4295 Mixed LC WLR 3-Oct-05
OAL 2.8 T = 87 F
Ave Vel = 2486
Std Dev = 19
ES = 61
Low = 2447
High = 2508
N = 12


168 Hornady Match 42.0 grs Varget wtd Lot 4295 Mixed LC WLR 3-Oct-05
OAL 2.8 T = 87 F
Ave Vel = 2541
Std Dev = 17
ES = 51
Low = 2514
High = 2565
N = 12

168 Sierra Match 43.0 grs Varget wtd Lot 4295 Mixed LC WLR 3-Oct-05
OAL 2.8 T = 87 F
Ave Vel = 2604
Std Dev = 15
ES = 49
Low = 2581
High = 2630
N = 20

case head separations too slow for M1a

REL1203
August 4, 2010, 10:28 PM
What kind of brass are you using? Is it military?

Mostly Mixed Commercial now, no Military. Its generally FC, Rem, PPU. I am about to put in an Order of New Win 308 Brass from Midway once the Aug coupons become active and start to build off those, but figured I had 300 or so mixed cheap Commercial brass I might as well start using it for a little while and see what my gun likes so I will have a good starting oint when it comes to my new brass

rcmodel
August 5, 2010, 01:50 PM
To "see what your gun likes" it would be best to sort the mixed brass by head-stamp and shoot it that way for testing.

rc

REL1203
August 5, 2010, 02:58 PM
To "see what your gun likes" it would be best to sort the mixed brass by head-stamp and shoot it that way for testing.

I am doing that as well, i meant more about what size pill they like... For my SASS, 168 or 175, and for my DPMS 62, 69, or 75g....

Hopefully i will be able to order my Win Cases for 223 and 308 soon and then just use my fixed brass as cheap blaster ammo

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