v1911 Posted April 15, 2016 Share Posted April 15, 2016 (edited) I decided to run a comparison of loads to see what velocity difference was being had between the 5" barrel of my STI and the 4" barrel. Obviously your results may vary but I wanted people to get a ballpark idea of what could be expected. I took my time and ran 10 shots over the chrony set at 10'. In an attempt to be as consistent between shots, I would raise the barrel in a vain attempt to keep the powder in the rounds in the back of the casing then slowly lower my sights. In hind sight this probably didn't accomplish anything seeing as the 147gr bullet is probably already kissing powder when seated. Following the chrony test I put 10 shot groups for comparison. The groupings were fired from the 5" at a range of just 7 yards. The 3 bullets we have today are the coated Acme 147gr (no lube ring), Bayou Bullet 147gr (lube ring) and Zero 147gr JHP. All rounds were loaded to an OAL of 1.150 with 3.2gr of Clay Dot. The 2 guns peforming the tests are the 5" Gans Guns 9mm STI w/ schuemann barrel and STI Costa VIP 4.0 w/ STI barrel. Again, YMMV. Zero 147gr 5" Avg: 897fps SD: 8.5 ES: 27 PF: 131 Acme 147gr 5" Avg: 919fps SD: 9.3 ES: 31 PF: 135 Bayou Bullets 5" Avg: 925fps SD: 9.6 ES: 32 PF: 135 Zero 147gr 4" Avg: 887fps SD: 15.9 ES: 53 PF: 130 Acme 147gr 4" Avg: 883fps SD: 15.4 ES: 48 PF: 129 Bayou Bullets 147gr 4" Avg: 902fps SD: 15.6 ES: 40 PF: 132 5" Test gun 4" Test Gun Edited April 15, 2016 by v1911 Link to comment Share on other sites More sharing options...
LilBunniFuFu Posted April 15, 2016 Share Posted April 15, 2016 Interesting to see how the sd and the es are consistent and so much better in the 5 inch gun than the 4. Do you think you would have the same result with a different 4 inch gun/barrel combo? Link to comment Share on other sites More sharing options...
v1911 Posted April 15, 2016 Author Share Posted April 15, 2016 I suppose if I were to take out the STI guardian as well, I'd have another 4" reference. I can't say for certain, but Internet lore seems to be saying that each gun and barrel is unique and that each will have its own, if not trivial, differences. Link to comment Share on other sites More sharing options...
Hi-Power Jack Posted April 15, 2016 Share Posted April 15, 2016 Be fascinating to see group sizes at 20 - 25 yards. Thanks for sharing. Link to comment Share on other sites More sharing options...
SNSCaster2 Posted April 16, 2016 Share Posted April 16, 2016 Were you using a ransom rest? It would also be great to know your OAL and seating depth for each. ES is not a true indicator of accuracy in this case if the groups didn't come from a solid ransom rest IMO Sent from my SAMSUNG-SM-G890A using Tapatalk Link to comment Share on other sites More sharing options...
3djedi Posted April 17, 2016 Share Posted April 17, 2016 (edited) You sure that's not a 6" and a 5"? Lol Sent from my SAMSUNG-SM-G935A using Tapatalk Edited April 17, 2016 by 3djedi Link to comment Share on other sites More sharing options...
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