940 ballistics

[Retired W4]

While looking at my 940 (no dash) and comparing it to other J frame .38 specials, I got to wondering about any advantage the 9mm might have over other short barrel revolvers in .38 Special. The SCSW says it has a 2 or 3 inch barrel, but mine is 1 7/8". It is not a super early version with a BFV serial number. It's hard to find muzzle energy numbers for a 9mm out of a 1 7/8" revolver.

I have been loading it with Federal 147 Hydra-Shok, but any information would be appreciated. Thanks.

 

[pilgrim6a]

The 940 will give you MVs comparable to a .357 mag snubby.
9mm is a high pressure round designed to perform in a 4" auto.
Also the auto barrel is measured from breach to muzzle. So the 940 would be 3.5" or like a compact 9mm auto.
My friend and I did some chrono tests 10 yrs. ago and found the 940 avg 1000-1100fps with standard pressure 9mm JHPs.

 

[Retired W4]

Thanks Pilgrim. That's what I was looking for. I plugged those numbers into Bill StClair's website and found that the muzzle energy from the 940 was above, or well above 300 ft.lbs. That's a pretty powerful J Frame.

 

[johngalt]

This also raises the big question: are .38 special cylinders and 9mm cylinders heat treated the same? Can a .38 special cylinder take the same pressure as the 9mm?

I understand the aluminum airweight frame is a different question and may not be up to it.

 

[bobf]

Mine has the same barrel length as yours. Going thru my book here is some of the info I have, may be more than you are looking for.

Remington factory 115 gr JHP Wal Mart box of 100.
Avg 1111

Reloads

124 gr Golden Sabre Powder: Power Pistol
5.2 gr--avg 998
5.4 gr--avg 1040
5.6 gr--avg 1057

115 gr FMJ Powder: Power Pistol
6.7 gr--avg 1150

115 gr JHP powder: Unique
6.0 gr--avg 1102
6.2 gr--avg 1123
Recoil noticeably less with Unique

Bob

 

[Tinygnat219]

Has anyone done any chronos of factory 9MM in a 940? I'd be interested to see anything that's out there. I love this little revolver and although even with moonclips, cartridge extraction can be sticky, I use this as a backup gun replacing my 640 loaded with 110 Grain Hornady Critical Defense.

Thanks!

 

[Retired W4]

Thank you for all the information, Bob. Since I am not a reloader I am pretty much stuck with factory fodder, but it's definitely interesting to notice the variations one can get by reloading ones own ammo. John posed a great question about the heat treatment of 9mm Vs. .38 special cylinders. Maybe someone will come up with the answer. I am seeing most velosities in the 9mm that exceed .38 special.

I think my little 940 is going to be in my rotation of carry guns. It is really sweet to shoot and is as reliable as they get.

 

[rug357]

Back around 1990, my friend and I chronographed a dozen 9mm and 9mm+P factory ammo out of 940 and compared them to several 38 Special and 38 Special +P factory ammo out of Chief Special and couple 357 Magnum factory ammo out of Ruger SP101 (this was before there was J frame 357mag).

I don't have all the data with me anymore but I was very impressed with the 9mm ammo out of that 2" barrel. At all similar weight levels the 9mm velocity was much higher than 38 Special or 38 Special +P and pretty close to 357 Magnum velocity.

One load I remember was Corbon 115gr JHP +P which averaged just under 1,250 fps (something like 1,248 fps) from the 2" 940 revolver. That was a fierce load... at both ends.

Federal 9mm 115gr JHP (Federal 9BP) averaged a little under 1,100 fps. In comparison, the Winchester 357 Magnum white box 110gr JHP out of the 2 1/4" Ruger SP101 was averaging just a little above 1,100 fps and the Winchester 38 Special +P 110gr JHP only averaged 910 fps out of a 2" model 36.

The hottest load of the day was the 357 Magnum Remington 125gr SJHP which averaged 1,275 fps from the Ruger.

That little 940 9mm revolver earned my respect that day.

I'll check to see if I can find all the velocity data from that day.

 

[Doug M.]

I love this little revolver and although even with moonclips, cartridge extraction can be sticky, I use this as a backup gun replacing my 640 loaded with 110 Grain Hornady Critical Defense.

Thanks!

*
If I recall correctly, I have seen this mentioned as a problem with the 940, in varying extents from minor to a big deal. I also recall seeing some on this forum a while back say that they had solved their problem with it by carefully improving the finish/polishing of the chambers.

Take that recollection for what it is worth. I'd guess that the higher pressure of the 9mm would be more likely to reveal imperfections in the cylinder.

 

[Tinygnat219]

Back around 1990, my friend and I chronographed a dozen 9mm and 9mm+P factory ammo out of 940 and compared them to several 38 Special and 38 Special +P factory ammo out of Chief Special and couple 357 Magnum factory ammo out of Ruger SP101 (this was before there was J frame 357mag).

I don't have all the data with me anymore but I was very impressed with the 9mm ammo out of that 2" barrel. At all similar weight levels the 9mm velocity was much higher than 38 Special or 38 Special +P and pretty close to 357 Magnum velocity.

One load I remember was Corbon 115gr JHP +P which averaged just under 1,250 fps (something like 1,248 fps) from the 2" 940 revolver. That was a fierce load... at both ends.

Federal 9mm 115gr JHP (Federal 9BP) averaged a little under 1,100 fps. In comparison, the Winchester 357 Magnum white box 110gr JHP out of the 2 1/4" Ruger SP101 was averaging just a little above 1,100 fps and the Winchester 38 Special +P 110gr JHP only averaged 910 fps out of a 2" model 36.

The hottest load of the day was the 357 Magnum Remington 125gr SJHP which averaged 1,275 fps from the Ruger.

That little 940 9mm revolver earned my respect that day.

I'll check to see if I can find all the velocity data from that day.

Thank you! This is pretty much what I was looking for. It doesn't look like it loses anything at all from such a short barrel and a cylinder gap.

 

[Tinygnat219]

*
If I recall correctly, I have seen this mentioned as a problem with the 940, in varying extents from minor to a big deal. I also recall seeing some on this forum a while back say that they had solved their problem with it by carefully improving the finish/polishing of the chambers.

Take that recollection for what it is worth. I'd guess that the higher pressure of the 9mm would be more likely to reveal imperfections in the cylinder.

Considering that I carry this gun as a BUG, I'm not too worried about extractions overall, but I definitely wanted to thank you for bringing that up. because if I need to reload the backup, it's been a BAD day... No, I have noticed the extraction problems, but I try to minimize it by cleaning the cylinder after each range trip. I also noticed that my SP101 9MM Moonclips seem to feed and extract better than the S&W Moonclips so I'm switching to the Ruger Clips.

 

[M2MikeGolf]

No, I have noticed the extraction problems, but I try to minimize it by cleaning the cylinder after each range trip

Interesting about the extraction issues; I've heard some 547 owners complain of the same. One 547 owner told me he made sure that there was no oil in the chambers after cleaning, and another one informed me that he would swab the chambers with acetone before firing and never had problems with extraction.

 

[st regis]

Good info on here....this is why this site rules. I carried a 640 as uniformed BUG until the 940 came out...got the 940, then the 357 came out so I had to get it..now..back with the 940 again. We keep Federal 115 +P+ in them. The Federal load is too hot for the extraction system on a 547 to easily work, but the moon clips handle them fine with a good firm smack on the extractor rod with the shooting hand.

 

[rug357]

Good info on here....this is why this site rules. I carried a 640 as uniformed BUG until the 940 came out...got the 940, then the 357 came out so I had to get it..now..back with the 940 again. We keep Federal 115 +P+ in them. The Federal load is too hot for the extraction system on a 547 to easily work, but the moon clips handle them fine with a good firm smack on the extractor rod with the shooting hand.

I believe that is the Federal 9mm BPLE load.
That was my 9mm carry ammo for many years.
One thing that was surprising about that load was that despite the +P+ designation it was not very fast. I have a whole page of data for this load from 1994.

Beretta 92F - 1,190 fps
Glock 17 - 1,230 fps
Glock 19 - 1,190 fps
Sig 226 - 1,170 fps
Sig 225 - 1,160 fps
H&K P7M8 - 1,210 fps
S&W 940 - 1,140 fps

These velocities are only about 40-50 fps faster than the standard pressure Fedral 9mm BP where as most other ammo maker's +P+ ammo were usually aboout 90-100 fps faster.

 

[David Sinko]

I shoot 124 gr. Gold Dots out of my 2" 940 at 1180 FPS. However, I prefer the 147 gr. Gold Dot at 1080 FPS. These are actual velocities over the chrono and they extract easily, using Power Pistol.

Dave Sinko

 

[M2MikeGolf]

The Federal load is too hot for the extraction system on a 547 to easily work

How does this affect the extraction system on the 547?

 

[st regis]

The little metal strips that make up the 547 extractor i think have trouble pushing hard enough on the rims to extract....i had my 547 pretty muck lock up after shooting the Fed BPLE in it...had to tap on the end of the extractor with a wooden handle to get the spent rounds out.....I settles for some Speed 124s after that....for the 547 to eat..

 

[tekarra]

I used Federal 9BP in my 547s and have not had extraction problems. Is the 9BPLE different from the 9BP?