BillR1 Posted August 30, 2015 Share Posted August 30, 2015 I'm trying to work up a single load to shoot in my SSP and CCP guns for IDPA, and I had some surprising results today through the chrono. My load is a 124gr Berrys RNHB with 4.1gr of Titegroup at 1.125" OAL. It's a nice load and very accurate. My full size P320 (4.7" barrel) averaged 1078fps for a 133+ pf. When I put the same rounds in my P320 Carry (3.9" barrel), I averaged 995fps for a 123 pf. The SDs on both guns were <15, so it's pretty consistent. The two tests were shot within minutes of each other using the same bag of ammo. Is this normal? It's less than 1" difference in barrel length... Link to comment Share on other sites More sharing options...
Bkreutz Posted August 30, 2015 Share Posted August 30, 2015 !" wouldn't make a lot of difference in a rifle, but in a pistol it does. Think of it this way, your shorter barrel is only 75% of the length of the longer one. Link to comment Share on other sites More sharing options...
IronicTwitch Posted August 31, 2015 Share Posted August 31, 2015 Yes. I had similar results between my CZ TS 5.1" and CZ P01 3.9", about 50-60 FPS less if I recall. And I was running 128PF for the TS, so I bumped up my load for dual use. The added recoil in the TS isn't really noticeable. Link to comment Share on other sites More sharing options...
bfalcon00 Posted August 31, 2015 Share Posted August 31, 2015 !" wouldn't make a lot of difference in a rifle, but in a pistol it does. Think of it this way, your shorter barrel is only 75% of the length of the longer one. That's actually a great way to think of it as far as a pistol is concerned. Elegant in its simplicity. Link to comment Share on other sites More sharing options...
b1gcountry Posted August 31, 2015 Share Posted August 31, 2015 Doesn't idpa allow you to crono with any gun you want? Link to comment Share on other sites More sharing options...
rev1911 Posted August 31, 2015 Share Posted August 31, 2015 That is a little more difference than I would have guessed, but nothing crazy. I chrono'd some 9mm loads out of a 4.25" 1911 that I run in USPSA occasionally, and found they were about 5-7% less than a XDM 5.25", and about 8-10% less than a G17L 6". Of course every gun and every barrel is a little different. Link to comment Share on other sites More sharing options...
BillR1 Posted August 31, 2015 Author Share Posted August 31, 2015 (edited) Doesn't idpa allow you to crono with any gun you want? The test gun has to be in the same division that you're competing in. I've seen matches where they have a gun at the chrono station with the longest allowed barrel for the division, which is 4.1" for CCP. Only if your ammo fails at making PF do they come and try the ammo through your gun. I've also seen them simply test with your gun. Edited August 31, 2015 by BillR1 Link to comment Share on other sites More sharing options...
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