Velocity vs Barrel Length (Pistol)

slimjim

I borrowed my friend's Glock 35 and took it, along with my quartet, to the range today and ran a variety of ammo through them across the Chronograph. Results are below. I was told the compensator on the 24C was only resulted in a 3% velocity loss. That might have been the case on the heavier loads but it sure wasn't on the 135gr JHP. I'm going to be getting a non-compensated 6" barrel for it so will have to run the velocities again.

slimjim

I could feel the extra kick of the 124gr NATO over the 115gr FMJs. Interesting that the 124gr NATO basically has as the muzzle energy of the 165gr and 180gr .40-cal. but not the Power Factor (Weight x MV / 1000). I'll have to do some tests on reactive steel targets to see if its Power Factor (momentum) or Energy (Weight x MV x MV) that is knocking them to the ground faster.

Ominivision1

Slim:

I have to ask why you would want a compensated barrel? Granted they might help with muzzle flip. Last year a buddy of mine had a comp barrel on his glock and with a laser sight. I gave up, trying to look for the laser after the flames cleared out was not for me. Remember that old song from Manfred Mann "Blinded by the Light".

Shooting it at an indoor range told me no comp barrel.

slimjim

I bought the 24C a long, long time ago. I made the choice for the comp because I wanted it for mostly target shooting and thought a 3% reduction in velocity was not a concern. I do carry it as my sidearm when hunting. I have never noticed any muzzle flash on this longer barrel (6"). The comp does noticeable help with muzzle flip but, if I had to do it again, I would not buy a comp barrel. It's much louder and the upward muzzle blast is nothing you would want close to your face. At one pistol match where it was raining, they had us shooting under those blue Walmart tarps. When I finished my first magazine, they all looked up at the deflating tarp that was perforated with holes. They made me shoot with my pistol outside of the tarp after that. They will let me shoot the long barrel at our local 3-gun but not with the comp so I'm going to buy an extra non-comp barrel.

slimjim

Here is a picture of the Glock 24 (6" long-slide) compensated barrel. It starts 2.375" from the end of the barrel and the slots get progressively bigger. I'm surprised the new front sight stood up to it so well. A painted white-dot sight would have been toast.

stovepipe

That's a ported barrel, no?

I thought comp's had expansion chambers post crown like a brake and were not part of the rifling, yes?

Slim you got the coolest graphs and stuff and I
m sprised too the insert didnt melt!

I wanna Glock

slimjim

stovey, you are probably correct. The barrel is ported. I think they are often interchanged. I've got to get the non-ported barrel and do some more comparison including some shot timing.

slimjim

BTW, the cut out in the slide is to reduce the slide weight to match the recoil spring. Glock uses the same recoil spring and adjusts slide weight accordingly. Thus the slide had the opening before the barrel ports were added.

stovepipe

Very cool. I likey that shooter man!

slimjim

Well, I got to the range today!!! I've been working too hard lately. The only good recoil therapy I've had lately was when I visited Stovey (thanks man!). After a shotgun action match this morning, I did a little pistol action with the new non-ported 6" barrel I got for my .40-cal Glock 24. I finished up my velocity comparison as shown in the graph below. Looks like the advertizing claim of a 3% velocity loss due to the ported/compensated barrel has some marketing hype spread on it. I averaged a 4% loss with the 135gr and 6% on the 165 and 180gr bullets. Basically, I effectively lost an 1" of barrel length due to the porting. Now I have to get this new set-up into the pistol action matches.

stovepipe

Them ported pistols work great in shooting competitions for speedy re-aquire. Wouldn't want one for defence...you'll evaporate yer eye lids if ya rock-it!

I keep tellin ya...get a 1911, ya can make major with my reduced 80% hardball load that ya shot w/ me and a 5" barrel really easy and not burn yer lips or tarps anymore! Laughing

Kidding- I like your comapros- I aint into numbers but yours are easy to digest. Interesting stuff. That tarp torching was classic!

Good luck and have the fun I know ya will at the next match buddy! *bang-bang-ding-ding!*

slimjim

stovepipe wrote:

Them ported pistols work great in shooting competitions for speedy re-aquire. Wouldn't want one for defence...

Thanks, stovey, I agree!

dan1dad

stovepipe I totally agree. 45 acp is the way to go. especially for CCW.

Like I say, why toss pebbles, when you can throw boulders.

I have heard solders coming back from the middle east say that when a half crazed angry enemy is charging at you wanting to kill you, 6 9mm rounds wont slow them down much, but a double tap from a 45 will knock them back into the dirt. I was told many were having family members send them 45s for side arms ,even though its not really approved of by the military, but they tend to over look it in Iraq and Afghanistan.

I can see it, if someones adrenaline is pumping, you will want the biggest slug you can hit them with. and just think if there is more than one person trying to kill you, you cant afford to empty your clip on one person and hope you can reload in time to get the rest. at 2 per person with a 45, you should be able to quell 4 or more if you get good hits.

But I am bias as I love my 45s. They are a hard hitting caliber that is affordable and effective.

slimjim

dan1dad wrote:

stovepipe I totally agree. 45 acp is the way to go. especially for CCW.

Like I say, why toss pebbles, when you can throw boulders.

I have heard solders coming back from the middle east say that when a half crazed angry enemy is charging at you wanting to kill you, 6 9mm rounds wont slow them down much, but a double tap from a 45 will knock them back into the dirt.

Not that I want to turn this into a caliber debate. However, using miltary expirence with 9mm doesn't carry much validity for me. As far as I am aware of, the military uses ball ammo. I would agree, using ball or FMJ ammo, a .45 out performs and will be more effective than the 9mm any way you look at it. Ball or FMJ is a poor choice, however, for any concealed carry situation. A 9mm offers easier concealment and with modern expanding bullets is viable.

Pumpkinslinger

Slim, I'm with you. Back to my "no magic guns, cartridges or bullets" thing. Carry what you're comfortable with.