Barrel Length - Revolver versus Semi-Auto

[BlindJustice]

Discussion Topic?

Revolver Barrel Length
measured from the forcing cone to the muzzle

Semi-Auto Barrel Length
Measured from rear of the Chamber to the muzzle.

So, I shoot a Full size 1911 5" Bbl.
& a S & W 625 5"Bbl.

the revolver has a full 5" of barrel rifllig
whereas the 1911 5" - 0.9" chamber

Note: Overall LEngth = 4" of barrel rifling
1911 5" O.A.L. 8.75"
S&W 625 JM 4" Bbl. O.A.L. 9.5"
S&W 625 5" Bbl. O.A.L. 10.5"

The revolver lloses somme pressure/velocity
due to the barrel to cylinder gap, so
is it 'fair' to compare the 19115" to a 625 5" Bbls
or should the revolver be a 4"'er?

perhaps somebody has some data via chronograph

Thoughts?

R-

 

[Jim K]

Compare how? In a BS session anyone can compare anything to anything, and that is the only place questions like that get asked and argued over.

I can think of no reason those measurements would make any real difference to anyone.

Jim

 

[jmr40]

I've seen this debated before and it is usually hard to compare apples to apples because there are only a few revolvers and semi's in the same chambering and similar barrel lengths. I've seen other posts where 9mm revolvers have been compared to similar length semi's over a chronograph. From the numbers I've seen posted the revolver should be a little faster with the same ammo and equal barrel lengths.

But if you measure them the same way, in other words if you included the length of the cylinder on a revolver and added it to the barrel length. And compared it to a semi with a similar length barrel, the semi will be a bit faster. I'm sure the cylinder gap accounts for this loss. It is not as much as a lot of folks think from what I can tell.

This would be like taking a 3" revolver, adding about 1.5"" for the cylinder, and comparing it to a 4.5" semi. I've not done this myself, but this is pretty much the results I've seen posted from others using a 9mm. I see no reason why a 45 would be any different. Hopefully someone has done this with a 45 and can post the results.

 

[BlindJustice]

Jmr40

* 9x19 doesn't have as much percentage velocity loss
in barrels 3.5" or less compared to .45 ACP

* adding the length of the cylinder to the semi-
auto's Barrel length

How about 5" 1911 vs the 625 4" JM
they are near in OAL 9.75" vs 9.5"
for a service/belt handgun & they
both have a nearly identical length of barrel rifling?

I guess yuou could also do this with a
Colt Delta Elite and a S&W 610 4" bbl.

R-

 

[BlindJustice]

Are there similar differences with the
listed barrel lengths for different types
of rifle actions i.e Single shot, botl action
Semi-auto.?

R-

 

[Rock185]

Blind, FWIW I have been able to do some chronographing between pistols and revolvers of the same caliber, 9MM, 10MM and .45ACP. I won't bore everybody with all the barrel lengths and specific factory and reloaded ammo used. What I found was, that in similar barrel lengths, the revolvers most always produced higher velocities than semi-auto pistols. This may be counterintuitive due to the revolvers having a flash gap where pressure is obviously bled off, but that's what the chronograph indicates. For example, 9MM standard pressure, +P and +P+ fired from my 3" Ruger and a previous 3" S&W generally gave higher velocities than my 4" semi-autos. With some factory ammo, my 5" S&W Model 610 revolver avarged 100+ fps more than my 5" 10MM S&W semi-auto pistols. One thing I have learned, is that you can't take anything for granted as far as what kind of velocities handguns, or rifles, will actually produce unless you chronograph a particular firearm with a particular load....ymmv

Jim K, there is no real reason that these results should be of interest to anyone. But, I admit to being curious, and interested in ballistics, so have done a fair amount of chronographing over the last 30 years or so...

 

[BlindJustice]

Thanks Rock.

Speer Ballistics tables

http://www.speer-ammo.com/ballistics/ammo.aspx

The detail for each load/cartridge offered
has Velocity Muzzle/50 yds/100 yds, and
and KE Ft Lbs for the same distance
then a trajectory given at 25 yds/50/75 & 100 yds
given it's sighed in at 25 yds.
bottom right hand corner it gives
barrel length for the advert. velocity.

9mm 4" & 3.5" SB*
40 S&W 4" & 3.5" SB
.45 ACP 5" & 4" SB
then the traditional Revolver rounds,
.357 Magnu 4V & 2V SB
.44 Special 6" & N/A SB
.44 Magnum N/A & 4V SB
.45 Colt 5.5" & N/A SB

* Magnums get the V suffix = vented
* seems to give velocity for
a 'typical' user's handgun.

.44 Special w/6" Bbl. seems curious
but then there's lots of 29/629 and Rugers out there in
.44 Mag.

& Speer seems lacking in .38 SUper
10mm AUto & .41 Mag.

Digression Drift , more coffee.

R-

 

[HexHead]

But if you measure them the same way, in other words if you included the length of the cylinder on a revolver and added it to the barrel length.

This would be like taking a 3" revolver, adding about 1.5"" for the cylinder, and comparing it to a 4.5" semi.

Why would you count the length of the cylinder, if the semi barrel length is measured from the chamber? If the OP is correct, and a 5" semi barrel is effectively 4.1" long, then it should be compared to a revolver with a 4" barrel.

In any case, the revolver should be more accurate.

 

[ATLDave]

I have always assumed that the barrel-cylinder gap just about compensates for the different means of measuring barrel length. Or that it comes close enough to it that I don't worry about the difference. If someone wanted to post actual chrono results shooting the same round out of a revolver and pistol with the "same" (but not really same) barrel length, I would read it with great interest. Anybody have such data?

 

[Rock185]

ATLDave, I have 30+ years of chronograph notes that have a few examples of "same" barrel length pistol and revolver velocities with same ammo.

Comparing S&W Model 610 revolver with 5" barrel and S&W 1006 semi-auto pistol with 5" barrel. Factory Remington 170 grain jhp: Revolver =1288fps, S&W 1006 pistol with 5' barrel=1250fps. Norma 200 grain JTC: 610 revolver=1221fps, 1006 pistol=1218fps. Winchester 175 grain Silvertip: Revolver=1267fps, 1006 pistol=1224fps. Winchester 180 grain FBI type ammo: Revolver=989fps, Pistol=935fps. CorBon 135 grain jhp: revolver=1585fps, pistol=1475fps. The trend of the revolver demonstrating higher velocities continued with 10MM reloads. Same trend continued with 9MM revolver and auto pistol chronographed velocities...ymmv

 

[ATLDave]

Rock185, thanks VERY much! Looks like the velocities are quite close, but with about a 50fps edge to the wheelie. I love data!