ancient-one
US Veteran
Using the Speer 158 gr LSWCHP as the example, the manual shows the max load of Bullseye(3.5 grs.) delivering 814 fps with a 6 inch Model 14. What do you estimate the velocity would be with a 2 inch barrel?
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How much does barrel length affect velocity?
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Erich
Member
Depends on all sorts of things: caliber, bullet weight, powder used. Given your example, I'd say 630 fps.
Skip Sackett
US Veteran
In 44Mag, about 15-30fps per inch.
This is what Hodgdon told me and I have seen it closer to 15fps/inch in my loads. My 1400fps round from a 5" M629 Classic end up close to 1800fps from my 20" carbine.
I would think it is powder dependent. Slower powders are going to give you more velocity, no doubt. The fps/inch may go up as the powder burns slower, not sure.
FWIW
This is what Hodgdon told me and I have seen it closer to 15fps/inch in my loads. My 1400fps round from a 5" M629 Classic end up close to 1800fps from my 20" carbine.
I would think it is powder dependent. Slower powders are going to give you more velocity, no doubt. The fps/inch may go up as the powder burns slower, not sure.
FWIW
Skip Sackett
US Veteran
After I posted I read Erich's post. I think he is a little low and I have some data to kind of show that. I use the same load for competition, 3.5gr Bullseye under my own cast 160gr bullet. I usually shoot it out of a 6" M586/M686 and get right at 790fps. Out of my 3" M60 I get right at 700fps.
I was going to get some data from the last rounds I shot from my M637 1 7/8". Only thing is though is that I cleared that data on the chronograph and lost it and those were my last rounds with me!
I'll have to do it again so I have those numbers stored!
I was going to get some data from the last rounds I shot from my M637 1 7/8". Only thing is though is that I cleared that data on the chronograph and lost it and those were my last rounds with me!
I'll have to do it again so I have those numbers stored!
Here is a "chart" mixed in some of the other FAQ's. Scroll down just a bit after the lock stuff, polishing and grips. Someone needs to organize this place.
http://smith-wessonforum.com/s-w-smithing/94072-faqs.html
http://smith-wessonforum.com/s-w-smithing/94072-faqs.html
MrPhil
Member
I've got the definitive answer to this question. Here it is. Are you ready?
It depends.
I did a test in February using a 9mm load designed to match my carry ammo. I used 4 guns. A Kahr PM9 (3 inch, polygonal rifling), Glock 19 (4 inch, polygonal rifling), Glock 17L (6 inch, polygonal rifling), and a Marlin Camp 9 carbine (16inch, Micro Groove rifling). Temp was in the low 50's. Strings of 10 shots over the chronograph.
The load: Montana Gold 124 grain JHP, 6.7 grains Hodgdon HS-6, Winchester SP. This is a +P load and is safe in my guns. It is close to Remington Golden Saber 124 grain +P
Barrel Velocity
3 inch 1041
4 inch 1146
6 inch 1231
16 inch 1251
Nothing linear about this at all. I've got a bunch of hypotheses to explain the differences, but not enough data to back them up. Not even sure how to design an experiment to provide the data.
It depends.
I did a test in February using a 9mm load designed to match my carry ammo. I used 4 guns. A Kahr PM9 (3 inch, polygonal rifling), Glock 19 (4 inch, polygonal rifling), Glock 17L (6 inch, polygonal rifling), and a Marlin Camp 9 carbine (16inch, Micro Groove rifling). Temp was in the low 50's. Strings of 10 shots over the chronograph.
The load: Montana Gold 124 grain JHP, 6.7 grains Hodgdon HS-6, Winchester SP. This is a +P load and is safe in my guns. It is close to Remington Golden Saber 124 grain +P
Barrel Velocity
3 inch 1041
4 inch 1146
6 inch 1231
16 inch 1251
Nothing linear about this at all. I've got a bunch of hypotheses to explain the differences, but not enough data to back them up. Not even sure how to design an experiment to provide the data.
Pisgah
Member
The intellectually honest answer is to say that , as a rule of thumb, the shorter the barrel the slower the velocity -- and even this does not always prove true. To try to guesstimate an average of some sort is an exercise in futility. Chamber size, cylinder gap or alignment, bore tightness or smoothness -- there are so many variables from gun to gun that vague generalities about length/velocity are pretty much the best anyone can do.
Now, throw in variables for the load -- bullet, brass, powder, primer, seating depth, crimp ... you get my drift.
Now, throw in variables for the load -- bullet, brass, powder, primer, seating depth, crimp ... you get my drift.
bmcgilvray
SWCA Member
When using otherwise identical Smith & Wesson revolvers, I've seen loads fired from 8 3/8-inch barrels that registered lower velocities than the same loads when fired from 6-inch barrels. This has been revealed with my long-snouted Model 14 .38 Special as well as with a 8 3/8-inch Model 27 .357 Magnum I used to have.
Generally though the longer the barrel the higher the velocity when considering barrel lengths up to 8 3/8-inch.
No way to accurately guess velocities for any given firearm. Velocities can vary greatly between two revolvers of the same brand, model, and barrel length.
Generally though the longer the barrel the higher the velocity when considering barrel lengths up to 8 3/8-inch.
No way to accurately guess velocities for any given firearm. Velocities can vary greatly between two revolvers of the same brand, model, and barrel length.
Dale53
Member
When you get to the .45 ACP, as an example, it can get even a bit more puzzling. Due to the expansion ratio of the "large bore for the powder charge", the .45 ACP shows even less difference between short and longer barrels. My Kimber CD Ultra II has a 3" barrel. It is down less than a 100 fps over my five inch 1911's.
You would think that the barrel cylinder gap of a revolver would put it way behind a 1911. Not so. My 5" 625-6 gets virtually the same velocity of the Model 1911's with a 5" barrel. The revolver has a barrel/cylinder gap that loses velocity but when you factor in the cylinder length, the same length barrel (but with a cylinder in the revolver) in the revolver gets the same as the "no barrel/cylinder gap .45 Auto".
You will normally find a pretty good difference in velocity in the full house .357 magnum between a snubby and a long barreled revolver. The .357 depends a good deal on barrel length to get it's power. The larger bores (.44 magnum and heavily loaded .45 Colt, "not so much").
Dale53
You would think that the barrel cylinder gap of a revolver would put it way behind a 1911. Not so. My 5" 625-6 gets virtually the same velocity of the Model 1911's with a 5" barrel. The revolver has a barrel/cylinder gap that loses velocity but when you factor in the cylinder length, the same length barrel (but with a cylinder in the revolver) in the revolver gets the same as the "no barrel/cylinder gap .45 Auto".
You will normally find a pretty good difference in velocity in the full house .357 magnum between a snubby and a long barreled revolver. The .357 depends a good deal on barrel length to get it's power. The larger bores (.44 magnum and heavily loaded .45 Colt, "not so much").
Dale53
You're right!!!
This experiment has been done in ballistic laboratories with a very long barrel, lots of ammo, and a hacksaw. The results always show IT IS NOT A LINEAR RELATIONSHIP.
It is a parabolic function, with the added velocity for each increment of added barrel length producing less and less of a velocity gain, until finally the added friction of more barrel length actually starts SLOWING the bullet.
If you want to buy a 36" .22 barrel and a hacksaw, you can (re)discover this for yourself.
oldRoger
US Veteran
Especially interesting is the fact that if you buy, cut, & test two or three barrels, you would get different results barrel to barrel. And we have reason to believe that we could influence the rate of change by changing the load.
And the bore size impacts the results as well, I think that I have seen that .22lr stan vel, achieves velocity peak at about 16” dependent of course on the barrel.
And a test done with a .45acp barrel showed the rate of change as the barrel was shortened to be very low.
And we know, or at least have reason to believe that the revolver could vary from chamber to chamber.
The correct answer does seem to be: Who knows? and/or It all depends.
And the bore size impacts the results as well, I think that I have seen that .22lr stan vel, achieves velocity peak at about 16” dependent of course on the barrel.
And a test done with a .45acp barrel showed the rate of change as the barrel was shortened to be very low.
And we know, or at least have reason to believe that the revolver could vary from chamber to chamber.
The correct answer does seem to be: Who knows? and/or It all depends.
If you are still burning powder throughout a 24" barrel, it will still increase muzzle velocity. My .45 Colt rounds with slow pistol powder get 1850 in a 24" 92 Rossi and only 1350 in a 6" revolver. For snubby rounds I think we should use Red Dot... the rest is just a flame thrower. Ace
MrPhil
Member
No thanks . . .
. . . . I'd rather not. Got enough other projects without cutting up barrels.
But seriously, thanks for the info.
. . . . I'd rather not. Got enough other projects without cutting up barrels.
But seriously, thanks for the info.
acl864
Member
38 Special- 3.5 gr Bullseye- CCI500 primer- TVB 158 gr LSWC- avg fps of 692 using a M642 with a 1 7/8" barrel- measured at 15' from muzzle.
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