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GGG problem
Posted: Mon May 14, 2018 12:13 pm
by shugie
I was enjoying myself at 600 yards on Century yesterday with some ammunition I'd made using vihtavuori, the results were more than acceptable, my best score ever and by some margin. But I'd not cooked enough of them , and reverted back to my usual GGG from the range office. I've had consistent results with GGG in my Swing, and was more than surprised to find it was all over the place, one round under the target, and no noticeable grouping. I can understand why it might land in a different place, but would at least have expected them all to land, more or less, in the same place.
I'm puzzled.
Re: GGG problem
Posted: Wed May 16, 2018 5:35 pm
by Mattnall
Changing ammo can have a dramatic affect on group size until the barrel gets mucky with the new fouling. I have found on changing ammo types I need to shoot 5-10 shots before they start grouping anywhere near I know they should.
Could this have been the issue?
Re: GGG problem
Posted: Wed May 16, 2018 5:53 pm
by hitchphil
.......which bullets in the home load? SMK 2215 or 2216 or X? & what NRA GGG? 147 MilSurp or NRA TR 155?
I have seen the MilSurp 147 GGG perform very poor groups vs GGG155 or RG 155
Re: GGG problem
Posted: Wed May 16, 2018 6:05 pm
by shugie
Home load SMK2156, GGG 155 match. My Swing has a non-standard Border barrel that only really likes 155.
Re: GGG problem
Posted: Wed May 16, 2018 6:35 pm
by Pete
Non-standard barrel? What twist? My Swing has a 1:11 Bartlein and I get the best results with 2155's, or 155 Scenars.
2156's were never as good.
Pete
Re: GGG problem
Posted: Wed May 16, 2018 7:29 pm
by shugie
Pete wrote:Non-standard barrel? What twist? My Swing has a 1:11 Bartlein and I get the best results with 2155's, or 155 Scenars.
2156's were never as good.
Pete
I don't know what the twist is, the only markings on the barrel are GI.309 F.300 Z.3070
Re: GGG problem
Posted: Thu May 17, 2018 1:39 pm
by breacher
Mattnall wrote:Changing ammo can have a dramatic affect on group size until the barrel gets mucky with the new fouling. I have found on changing ammo types I need to shoot 5-10 shots before they start grouping anywhere near I know they should.
Could this have been the issue?
This !!!
Very frustrating too.
Re: GGG problem
Posted: Thu May 17, 2018 1:48 pm
by shugie
breacher wrote:Mattnall wrote:Changing ammo can have a dramatic affect on group size until the barrel gets mucky with the new fouling. I have found on changing ammo types I need to shoot 5-10 shots before they start grouping anywhere near I know they should.
Could this have been the issue?
This !!!
Very frustrating too.
That's new to me. Could be the explanation, certainly better than anything else I can think of, thanks!
Re: GGG problem
Posted: Sat May 19, 2018 6:26 am
by Mattnall
shugie wrote:breacher wrote:Mattnall wrote:Changing ammo can have a dramatic affect on group size until the barrel gets mucky with the new fouling. I have found on changing ammo types I need to shoot 5-10 shots before they start grouping anywhere near I know they should.
Could this have been the issue?
This !!!
Very frustrating too.
That's new to me. Could be the explanation, certainly better than anything else I can think of, thanks!
I've found it's particularly bad with 22LR ammo as well. I guess smaller, slower bullets are affected more by the changes.