Shadowrider Posted March 10, 2010 Share Posted March 10, 2010 Was testing some 9mm loads today at 7 feet. Using a Glock 17 and an M&P 9. Both guns were running almost identical averages with the same load. As my buddy was getting ready for Double Tap and the loads were running close to 140PF, he says he was going to drop the charge. I said lets see what it is at 15 feet before you go dropping the load. The velocity average dropped by 50 FPS. We are looking at each other like WTH?!?! So he gets the other gun and fires it at the longer distance too. Same exact 50 FPS drop. Has anybody else seen a 50 FPS drop in about 8 feet? The chrono we used was my CED Millineum. These were 10 round groups. Link to comment Share on other sites More sharing options...
LPatterson Posted March 10, 2010 Share Posted March 10, 2010 First thought is that 7' is too close and you are getting muzzle blast influence, CED recommends 10-12' for pistol. Link to comment Share on other sites More sharing options...
Sarge Posted March 10, 2010 Share Posted March 10, 2010 First thought is that 7' is too close and you are getting muzzle blast influence, CED recommends 10-12' for pistol. I concur. Link to comment Share on other sites More sharing options...
Flatland Shooter Posted March 10, 2010 Share Posted March 10, 2010 (edited) Not a whole lot of information given, but if you are shooting 9mm 147gr RN bullets at 140 PF, the muzzle velocity is approximately 952 fps. Using a simple ballistic calculator found on the internet (http://www.handloads.com/calc/), the velocity at 5 yards is 947 fps and at 10 yards is 942 fps. A far cry from a 50 fps drop. Kind of confirms muzzle blast causing false readings up close. Bill Edited March 10, 2010 by Flatland Shooter Link to comment Share on other sites More sharing options...
Shadowrider Posted March 11, 2010 Author Share Posted March 11, 2010 Not a whole lot of information given, but if you are shooting 9mm 147gr RN bullets at 140 PF, the muzzle velocity is approximately 952 fps. Using a simple ballistic calculator found on the internet (http://www.handloads.com/calc/), the velocity at 5 yards is 947 fps and at 10 yards is 942 fps. A far cry from a 50 fps drop. Kind of confirms muzzle blast causing false readings up close. Bill That's a whole lot closer to what we were expecting and makes perfect sense. Thanks. Link to comment Share on other sites More sharing options...
Shadowrider Posted March 11, 2010 Author Share Posted March 11, 2010 Thanks guys for your replies. I appreciate it. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now