Velocity differences between revolver barrel lengths 38 special

[chase45]

I recently got a new chronograph so Ive been nerding out a little bit with it.

Thought this data might be of interest here as far as velocity differences go between barrel lengths of current Smiths. I dont intend for anyone to copy the load data as some of these loadings can be dangerous in the wrong combination of gun.

These are all from current catalog offerings of Smith. Guns used were a 1 7/8" 642, 3" 686+ and a 4 1/4" 66

I seat these HBWC just sub flush and add a roll crimp. The 642 velocity is not a typo. My 642 shoots this load a little faster than my 3" 686 per the chrono. It had a few push into the 800s which skewed the data upward but its what it reported.

Average FPS of 10 shot groups with each gun and load

148GR HBWC load with 3.5 grains of 231.

4.25" 66 - 810 FPS

3" 686 - 770 FPS

642 - 780FPS

160GR 358439 Cast Keith HP with 4.0 grains of 231. Standard 38 load


4.25" 66 - 792 FPS

3" 686 - 764 FPS

642 - 744 FPS

160GR 358439 Cast Keith HP with 4.5 grains of 231. +P loading. I dropped off the 642 here as the +P version really pushes the POI high in it so I dont use it.

4.25" 66 - 897FPS

3" 686 - 852 FPS

160GR 358439 Cast Keith HP with 8.2 grains of HS6. This is a 38/44 loading I have duplicated. This one is near magnum and HIGH PRESSURE. DO NOT USE IN ALLOY FRAME 38s

4.25" 66 - 1162 FPS

3" 686 - 1103 FPS

 

[Alk8944]

This information means absolutely nothing to anyone but the OP and HIS guns!

The generally accepted velocity variation for revolvers based on length is there is 25 to 50 FPS difference per inch of length, but this is highly variable. For example it is not unusual to find a 4" .38 Special that shoots faster than a 5" barrelled version of the same make and model when actually chronographing loads. The only thing that can be said reliably is that longer barrels are usually faster than shorter barrels, and vice-versa.

 

[steelslaver]

Ballistics by the inch gives velocities of different ammo using the same gun as the barrel is chopped 1 inch at a time

BBTI - Ballistics by the Inch :: Calibers/Cartridges

(statement of intent)

ballisticsbytheinch.com

 

[Rock185]

I've always been ballistically curious, and have been using chronographs since the '70s. Yes, every gun is an individual, and you really don't know what this or that load is going to do until it is chronographed in your particular gun/s. Within my humble experience, published factory ammunition velocities are usually at least in the ball park, but published loading manual velocities may be off significantly from that produced in any particular shooter's gun/s. As ALK8944 indicated; longer barrels usually generate higher velocities. But he has seen, as I, the OP and others have, that shorter barrels sometimes produce higher velocities than longer barrels. I have sometimes chronographed ammo in 4-5" pistol barrels that is faster than the same ammunition in a 16" barrel. But other shooter's gun/s might give different results. Some years ago, Dave Andrews, writing for Speer, wrote an informative article on the subject titled, "Why Ballisticians Get Gray". Even though other's chronograph data may not apply specifically to me, or differ greatly from mine, I'm always interested in seeing other shooter's results..

 

[saleen322]

While I have a chronograph, I usually use the guesstimate of 35 FPS per inch in the norm. That has always been in the ballpark. It is interesting to see posts like this just to see what someone else gets in actual handguns. Thanks for posting.

 

[chase45]

Magnum load with 15.5 grains of H110 and a 160Gr cast Keith HP. Seated deep and crimped above the front driving band

 

[Rock185]

Chase45, I would think your load would be about maximum, and handle anything that could be handled by a ..357. Seems similar to the hottest factory load I've encountered. That factory load that is warmer than any other factory or handloaded .357 load I've used; the Buffalo Bore .357 180 WFNGC. They advertise it as doing 1400 FPS in a 4" revolver. It actually does that in my 4" and 5" revolvers, and just over 1500 FPS in a 5.5" gun.

 

[max503]

Me and a friend were plinking on somebody's farm one day. We were shooting at a car door. One of the old ones with thick metal. We were using the same ammo.
Bullets from his Ruger semi-auto penetrated the car door. Bullets from my 4" S&W revolver did not.
Sorry if I am off topic, but it relates to velocity.

 

[BoulderTroll]

Me and a friend were plinking on somebody's farm one day. We were shooting at a car door. One of the old ones with thick metal. We were using the same ammo.
Bullets from his Ruger semi-auto penetrated the car door. Bullets from my 4" S&W revolver did not.
Sorry if I am off topic, but it relates to velocity.

This guy does a very interesting video on cylinder gap and how much velocity is lost. Of course it's weapon specific, since there will be variances in the size of the gap, the ammo, etc., but his results were interesting. A 4" barrel revolver effectively has the same barrel length as a 5.5" semi-auto, and loses roughly 3.4% velocity through the cylinder gap (in his test example). I think people generally believe there is far more velocity lost than there actually is. Especially when you consider that he is comparing a 4" revolver to a 5.5" auto, shooting the same ammo. All things considered, a 4" revolver will always have more velocity than a 4" auto, using the same ammo:

 

[chase45]

Yes I believe it's pretty maxed at this loading with the h110. Same for the hs6 load.

I've always been curious how some of the boutique outfits do it. I've heard they blend powder/canister grade etc. But one would think if that were the case a batch would be made up for guys chasing high velocity.

This load is plenty for my uses. I carry it pretty often. I shoot the hs6 load a bit more. Little easier to handle and a bit more economical while having plenty of power.

I love the revolver because you can load them from light to yikes

The RO came over to see which rifle I was shooting when I was blasting away with the h110 loads lol

 

[rwsmith]

I've always been ballistically curious, and have been using chronographs since the '70s. Yes, every gun is an individual, and you really don't know what this or that load is going to do until it is chronographed in your particular gun/s. Within my humble experience, published factory ammunition velocities are usually at least in the ball park, but published loading manual velocities may be off significantly from that produced in any particular shooter's gun/s. As ALK8944 indicated; longer barrels usually generate higher velocities. But he has seen, as I, the OP and others have, that shorter barrels sometimes produce higher velocities than longer barrels. I have sometimes chronographed ammo in 4-5" pistol barrels that is faster than the same ammunition in a 16" barrel. But other shooter's gun/s might give different results. Some years ago, Dave Andrews, writing for Speer, wrote an informative article on the subject titled, "Why Ballisticians Get Gray". Even though other's chronograph data may not apply specifically to me, or differ greatly from mine, I'm always interested in seeing other shooter's results..

Same here. That is a very informative article. It's amazing the difference between the same barrel length even in guns of the same make, much less different brands.

 

[Chuck Edwards]

Way back when I was an active IDPA competitor, I chronographed my match load from all the 4" revolvers I had. The K&L frames and my Colt Official Police were all within about 20 fps of each other. My two N frames (27-3 and 28-2) were about 70 fps slower. My 3" 10-7 runs about the same velocity as those 4" guns, and my 3" 64-6 is about 20 fps slower; both of those guns are relatively recent acquisitions.

I recently switched to High Desert's .357 Magnum loading using a 158-grain Hornady XTP at an advertised 950 fps from a 4" barrel. Ammo from the same box went 916 fps from my 4" 19-3 and 991 from my 681-2. It's the most accurate factory load I've found in .357 and uses a very low-flash powder (yes, I tried it at night).