Author Topic: Barrel length vs bullet speed (Read 689 times)

dewy · « **on:** March 05, 2006, 06:41:42 AM »

Yesterday I was shooting my two 44's and using my chrony to check the bullet Velocity and noticed that 1. the Difference between the five and a half barrel and seven and a half was only about 20-30 feet per second different and 2. that an old box of American eagle 240gr jhps where averaging 1820-1850 with either gun.
Is it possible to get that kind of velocity out of the 44mag and why is their not much difference in those to barrel lengths?

Any ideals please let me know. :wink:

swampthing · « **Reply #1 on:** March 06, 2006, 02:48:03 PM »

I would check that again, maybe 10 feet from the crony. Typically JHP's go 1450 or so, max, out of sub 9" revolvers. 1850 seems a little rediculous from a revolver.

Mikey · « **Reply #2 on:** March 07, 2006, 01:50:24 AM »

dewey: When I first read your post I thought your velocities were high. As swampthing said, velocities for the 44 mag usually run about 1400-1450, so you may wish to check your chronograph.

However, as to the differences in velocity betwixt the two revolvers - there are a couple of factors that come into play: cylinder to barrel gap is one (may be less on one of the revolvers), cylinder bore is another (one may be a hair bigger than the other) and, of course barrel length.

Normally you lose about 50'/sec per inch of barrel and if you are getting less than that I would suspect a tight barrel gap in the shorter revolver and a larger one in the longer one. Just a thought here. Mikey.

sawfish · « **Reply #3 on:** March 07, 2006, 10:06:58 AM »

I agree with Swampthing. Sounds like you might be too close, and the chrono screens are recording the initial blast (and appurtenant powder particles) instead of the bullet. I had the same experience chronographing loads out of Super Blackhawks of various lengths, but could not duplicate the same velocities on a different day.

A similar problem with different results (no reading) occurs in bright sunlight with shiny bullets. I have had to resort to an umbrella, or darkening the bullet with a black marker. Sometimes chronographs create more mysteries than they solve.

Redhawk1 · « **Reply #4 on:** March 07, 2006, 10:29:47 AM »

That would put your 44 Mag at 454 Casull velocities. Seems high.

KN · « **Reply #5 on:** March 07, 2006, 12:12:26 PM »

Thats about right for a 180gr bullet at max H110 velocity. But I doubd you can get that with a 240gr. KN

dewy · « **Reply #6 on:** March 09, 2006, 02:32:30 AM »

thanks for the insight and I plan on trying it again a little further from the chrony. but it is strange that my reloads where only at 1424 from the same distance could just be the powder.
the two rugers one was amost new and the other was well used.
thanks dewy :grin:

sawfish · « **Reply #7 on:** March 09, 2006, 05:43:53 AM »

Put your screens out about 15 feet from the muzzle. You may be correct about the powder causing this anamoly. If you had a number of grains of unburnt powder (usually slower burning), that could have triggered the screens. The 15' distance should solve the problem. Let us know about your results. Good luck.

nomosendero · « **Reply #8 on:** March 09, 2006, 03:17:38 PM »

Yea & if that doesn't solve the problem & the cases aren't sticking, I want
some of that stuff!!