Unleashed Posted September 25, 2006 Share Posted September 25, 2006 (edited) I put a storm lake bbl in my G22 and it has been working great. The accuracy is very nice (not that it was a problem before, I just wanted more case support). The problem I am having is an apparent loss in velocity. I was clocking my major load right before the L10 Nationals and found that I was about 30fps slower than normal, prompting me to bump up the charge. I am running into the same problem with my Production load. Even with rounds that I have chrono'd before, I am losing about 30fps. Has anyone else experienced this type of thing with an aftermarket bbl? I am going to put the factory bbl back in and do some testing but I wanted to get some opinions so I don't lose too much sleep over it. Thanks, Edwin Edited September 25, 2006 by Unleashed Link to comment Share on other sites More sharing options...
LJE Posted September 25, 2006 Share Posted September 25, 2006 30 fps slower is not all that bad. I have tested several aftermarket barrels for 9mm major and have seen velocities 120 fps slower than a Glock barrel. The polygonal rifling in the Glock barrel creates less drag on the bullet than conventional rifling does. If the accuracy of your new barrel is good, just bump up the load a bit and live with it. Larry Link to comment Share on other sites More sharing options...
open17 Posted September 25, 2006 Share Posted September 25, 2006 I had 2 Storm Lake barrels that came off of the line next to each other. They were in 2 Glock 17 Open guns, with identical barrel porting and very similar comps. Those two barrels with identical ammo were about 40 fps apart. You have changed rifling systems along with barrel brands. I'm suprised it's only 30 fps! Link to comment Share on other sites More sharing options...
Unleashed Posted September 25, 2006 Author Share Posted September 25, 2006 That does make sense and I'm glad I found the culprit. It was no big deal when I was shooting a major load (the difference in felt recoil was negligible) but with my minor loads, I can tell a huge difference! I think for Production I will just put the factory bbl in. The accuracy was just fine but I had a case head separation from shooting Clays+PMC brass so the Storm Lake bbl was there for support more than anything. Thanks for the replies! Link to comment Share on other sites More sharing options...
SRT Driver Posted September 25, 2006 Share Posted September 25, 2006 KKM bbls have the same issue..about 25-40 fps slower. My understanding of the faster velocity out of a stock glock bbl is that the I.D. of the stock bbls decreases slightly as it gets closer to the crown. It screws the bullet into the rifling creating a better bite and less pressure loss equating to slightly higher velocity. Link to comment Share on other sites More sharing options...
Unleashed Posted September 29, 2006 Author Share Posted September 29, 2006 I confirmed the actual velocity lost today in a side by side comparison: 165 Zero FMJ 3.4 gr Clays Win Small Pistol Primer 1.135 OAL Starline Brass Storm Lake bbl: Avg Velocity=740 Glock Factory bbl: Avg Velocity=805! Needless to say, I will be shooting my factory bbl at the Nationals. I re-clocked my major loads from the L-10 Nats and it made a 181PF in the stock bbl. The Storm Lake was 175PF! Just some food for thought when you change bbls. Link to comment Share on other sites More sharing options...
curmudgeon Posted September 29, 2006 Share Posted September 29, 2006 I bought Storm Lake's 40 to 9mm conversion for my G35. I don't have velocities to compare, but the accuracy was very poor. My 3" groups at 25 yards became 6" +. Has any one else had such experience? Link to comment Share on other sites More sharing options...
ipscbob Posted September 30, 2006 Share Posted September 30, 2006 I bought Storm Lake's 40 to 9mm conversion for my G35. I don't have velocities to compare, but the accuracy was very poor. My 3" groups at 25 yards became 6" +. Has any one else had such experience? Not exactly the same but.....I started an open gun build in 38 super with a storm lake barrel that I bought through this forum. During fitting the smith said the barrel lugs cut like butter. We proceeded anyway and after 1000 rounds of break in, the wear was so bad we pulled out the barrel and replaced it. Soft is an understatement Link to comment Share on other sites More sharing options...
Adam B Posted September 30, 2006 Share Posted September 30, 2006 Not exactly the same but.....I started an open gun build in 38 super with a storm lake barrel that I bought through this forum. During fitting the smith said the barrel lugs cut like butter. We proceeded anyway and after 1000 rounds of break in, the wear was so bad we pulled out the barrel and replaced it. Soft is an understatement Wow, that is terrible, did you contact storm lake about it? I had 2 of their barrels in my glock and they were great. Link to comment Share on other sites More sharing options...
f250sd Posted October 1, 2006 Share Posted October 1, 2006 I got higher vel out of my KKM barrel when shooting 147gr minor load in my G34. About +20 fps. I guess there are so many factors involved, you just can't predict vel out of a different barrel. Link to comment Share on other sites More sharing options...
Harmon Posted October 1, 2006 Share Posted October 1, 2006 my KKM was faster in both of my guns storm lake in my 34 is within 15 fps of my factory barrel. Link to comment Share on other sites More sharing options...
Smokecloud Posted October 10, 2006 Share Posted October 10, 2006 in my G35, my KKM is about 20-30FPS faster than stock. Link to comment Share on other sites More sharing options...
bountyhunter Posted October 10, 2006 Share Posted October 10, 2006 I bought Storm Lake's 40 to 9mm conversion for my G35. I don't have velocities to compare, but the accuracy was very poor. My 3" groups at 25 yards became 6" +. Has any one else had such experience? I've had the opposite experience with Firedragon aftermarket 40 to 9mm barrels in my Glock 35 and SIG226. A 6" group indicates something is VERY wrong. Link to comment Share on other sites More sharing options...
pstew Posted October 14, 2006 Share Posted October 14, 2006 My G34 storm lake barrel is 30 - 40 fps slower than the stock barrel. It dosent seen to depend of bullet weight. The barrel is more accurate for all loads i've tried Link to comment Share on other sites More sharing options...
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