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Discussion Starter · #1 · (Edited)
Greetings all from "Longrider" , a new member, and I have a question regarding muzzle velocity. Out of curiosity, I chrono'ed various 9 mm ammos - Winchester, Speer, Federal, Underwood, Blazer-out of my old P225, 3.7" barrel ,and compared that with the 4.7" barrel of my new P320. Results were not what I expected. The 3.7" barrel of the older P225 produced velocities marginally better than the new 4.7" of the P320. With the "ProChrono Digital", I recorded velocities in this 3.7" to 4.7" comparison. Examples : The Winchester 115gr. JHP velocity was 1162 out of the 3.7" P225 & 1142 from the 4.7" P320; The Hornady XTP 115 gr. was 1170 from the 3.7" & 1129 from the 4.7"; Federal HST 124gr was 1166 in the 3.7" & 1160 in the 4.7"; Speer GD 124gr+P was 1201in the 3.7" & 1185 in the 4.7". Is it funny to you that the 4.7" barrel (P320)comes in with lower (marginally) or equal only to the 3.7 " barrel (P225)? Is some minor deviation/flaw present in the new P320 or something else at work ? I'm trying to understand how a longer barrel (by one inch) pistol ,new, can come up with slower velocities than the older P225. Strange to me. Ideas gentlemen ?? Thanks from a newcomer
 

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Pure speculation...

One pistol has a tighter bore (we sometimes request for slightly smaller bores in our bolt guns with shorter barrels, to get the same MV we'd normally see with a longer barrel), or better lock time (?).
 

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First, welcome to the site! I have to admit I don't get too far down in the weeds over these things, but as I understand it, the velocity advantage for longer barrels isn't for distances up close, but for further out. I'm not an expert on these things, but in my reading and watching a few of these tests, that seems to be the most common theme. I wouldn't put too much into these marginal differences for the average defense situation.
 

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Discussion Starter · #5 · (Edited)
Actually in buying the P320 full size with the 4.7" barrel, I thought I'd be getting greater M.V. and therefore able to reach out a bit over the 3.7", but who knew the velocity increase was not there. Thanks for your replies.In addition, M.V. can effect bullet performance, expecially in JHP ammo, so I thought adding velocities with the longer barrel would be a good thing. Example, the Speer GD124gr. standard JHP doesn't open as reliably as the +P version(in the videos I've seen) . So, though not a game changer, I just thought I'd be picking up some velocity with the longer barrel but strangely this was not the case. Enough said and thank you all. I'm glad to be a member of this forum !!
 

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My thought is that the ammo was designed to perform "best" out of the shorter (duty/carry length) barrel. Slower burning powder would perhaps reverse your results.
 
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Actually in buying the P320 full size with the 4.7" barrel, I thought I'd be getting greater M.V. and therefore able to reach out a bit over the 3.7", but who knew the velocity increase was not there. Thanks for your replies.In addition, M.V. can effect bullet performance, expecially in JHP ammo, so I thought adding velocities with the longer barrel would be a good thing. Example, the Speer GD124gr. standard JHP doesn't open as reliably as the +P version(in the videos I've seen) . So, though not a game changer, I just thought I'd be picking up some velocity with the longer barrel but strangely this was not the case. Enough said and thank you all. I'm glad to be a member of this forum !!
Yeah, this is one of the reasons I went with a Glock 19 over the Glock 17. The slightly longer barrels really don't add enough of an advantage over the shorter barrels, until you get into 5"+ barrels, so there is no real advantage in going with the longer guns for "carry". I'd prefer to have a little lighter gun that is a little easier to conceal, and is a little more versatile. Welcome, again. See ya around thr forum.
 
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Welcome to our forum.

Full size SIG Sauers and classic USGI 1911s have always been among my favourite guns; I never stop learning, and after almost 38 years of guns-ownership I still enjoy shooting my own reloadings at least twice a week.
This is one of the best gun forums among the several I belong to, hope you'll enjoy your time here.

Shoot safe.
 

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What's the round count out of those two barrels? The older 225 (which I'm guessing has a higher count) may have a more worn-in barrel and have a "smoother" bore, allowing slightly higher velocities.
 

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Welcome to SigTalk. Your test is interesting. Even though the longer barrel seemed to show less velocity, it should prove to stabilize a bit more with an inch more barrel twist.
That should increase accuracy out to a great distance. Maybe I'm all wet but it is a thought. In any event, I hope you enjoy your time here. Greetings from the flat lands of Kansas.
 
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