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).

 

[Lance Boyle]

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.

Yep, I have a fair amount of 4” guns and 6” guns in .357. They vary, I think people tend to forget the cylinder gap is not inconsequential and they vary in width.

 

[Yendor357]

A chronograph is an eye opener, that’s for sure. Since the introduction of the Garmin Xero, I’ve been a pretty staunch advocate. Often, my opinion is countered someone stuck in their ways. It’s heartening to see like thinkers exist.
Why anyone would choose ignorance over knowledge, is something I hope I never understand.

Like the rest of you, when I first started chronographing I occasionally, I got a result or 2 that made me question the chronograph itself. Some of those old standbys rules that we never questioned, turned out to be way off track.

Why does a 3 inch Python outrun a 6 inch 686? Why is my 185 grain HP in 45 ACP going almost 200 FPS faster than the book says? Doesn’t make any sense, does it? The only thing I know for sure is my Garmin has no biased opinions, never read any books, and doesn’t care about the rules. It just tells it like it is.

Makes you wonder, doesn’t it? How many guns suffered undue wear from a load that was hotter than published? Why am I lugging around an extra 3 inches of barrel? Because we never did our own fact-checking, that’s why. If you’re not using a chronograph, you simply do not know what’s going on.

*While I’m on my soap box, Get a trigger pull gauge, a good set of gunsmith’s screwdrivers, and if you post a pic of a good target (which I always like to see) say what distance.

 

[Riposte1]

There are "fast" guns and "slow" guns - both revolvers and autos but I find more difference in revolvers.

I have a model 19 (think it is a -3 but I'd have to confirm that) that I think was made on a Friday when the tooling was worn (actually I have no idea at what interval S&W changes their tooling) - but back in the 70s I loaded up some 158 SWCs with the charge of H-110 that is recommended in the Lyman Cast Bullet manual) and it gave 1450 fps from the 4" barrel!

I had sold my 8 3/8" 27 by the time I owned a chrono, but it didn't get that in my 6" Python! And the only other .357 I had at that time was Ruger Flattop 4 3/4 that had been nickled - it got about 1400 in that gun.

+1 on the chrono. I'm not sure about the radar ones but I have 6 or 7 chronos (buy them mostly cheap off of eBay but I have three I bought new - I once put a Chrony in the middle of my Oehler scy screens and fired 10 5.56 m-193 ball over them - there was 1 fps difference in the average!).

Occasionally one with sky screens will give odd readings. I once taught a class at one of Evan Marshall's "Hoot and Shoot" events and I took my 9X23 and some ammo - we were using Evan's chrono near the end of the day and the shadows were getting long - I fired 3 rounds over his chrono and the average was over 2300 fps - we decided to quit then because that ammo could not have been over 1500.

Just Ramblin'

Riposte

 

[CH4]

OP, thanks for posting your test results.

 

[Yendor357]

Case in point.

*To be honest, one shot went a little high, off paper, hence the “5 of 6”. The high shot probably doubled the group size. I’m not a machine. Needless to say, I’m pretty happy with the Wilson rear sight. I quit after this happened. (I can shoot at home)

 

[mtgianni]

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

I remember that combo being written about in the early 90's as "Blackhawks only and use small rifle primers". Chronos have shown us a lot of what was conjecture may just not have been true.

 

[Chuck Edwards]

Case in point.

*To be honest, one shot went a little high, off paper, hence the “5 of 6”. The high shot probably doubled the group size. I’m not a machine. Needless to say, I’m pretty happy with the Wilson rear sight. I quit after this happened. (I can shoot at home)

Nice! I used to be able to shoot that well. Well done!

 

[Yendor357]

Chuck, I’ll bet you still can.
I have a really good eye doctor, I’m turning 65 soon. The eye doctor has me in bi focal contacts. Thats my “cheat”. I would never be able to shoot as well in glasses.
Since I retired 2 years ago, I shoot a lot more. I’ve always been an Elmer Keith deciple. I just copy his “sitting braced” position.

All of my new Colt revolvers have Heffron trigger jobs. Most have Wilson rear sights. That is my other cheat, good triggers, and good sights.

I piddle around with cast/commercial bullets occasionally. But my Go-to is an XTP in any caliber. My powder charge a little below the listed maximum charge. H110 and Accurate 5,7,9 for powders.