Safe to shoot 9mm in a .38 Super Revolver?Looking at a used S&W PC 627-4 revolver in

nola000 · #1 08-22-2018, 03:38 PM

New here. Been lurking forever and just realized I never registered. Figured this is a good topic to break my S&W forum cherry on.

Looking at a used S&W PC 627-4 revolver in .38 Super . I really want the S&W 929 which is 9mm because 9 is what I want to shoot but I can get the .38 Super cheaper.

Is it:

1. Possible
2. Safe
3. Reliable
4. Damaging

...to shoot 9mm through this .38 Super?

robertrwalsh · #2 08-22-2018, 03:43 PM

Not physically possible. 9mm cartridge is about 0.004 wider at the base than .38 super. Will almost certainly not chamber, at least it shouldn't. If it does, something is wrong.

epj · #3 08-22-2018, 04:16 PM

You might be able to rechamber the .38 to 9mm. The 9mm is a tapered case.

505Gibbs · #4 08-22-2018, 04:25 PM

Quote:

Originally Posted by nola000

New here. Been lurking forever and just realized I never registered. Figured this is a good topic to break my S&W forum cherry on.

Looking at a used S&W PC 627-4 revolver in .38 Super . I really want the S&W 929 which is 9mm because 9 is what I want to shoot but I can get the .38 Super cheaper.

Is it:

1. Possible
2. Safe
3. Reliable
4. Damaging

...to shoot 9mm through this .38 Super?

Unless you get a steal or the gun is beat up the 929 should be much cheaper than the 627-4 which usually bring good money!

colt_saa · #5 08-22-2018, 04:41 PM

Welcome to the Forum

My 627 has a second cylinder chambered for 9x23 Winchester

Since rimless cartridges fired in S&W revolvers (except the 547) head space on the moon clip instead of the case mouth, you can safely chamber and fire all of the shorter cartridges in that family.

So my revolver will also work just fine with 38SUPER, 38ACP, 356TSW, 9x21, 9MM Parabellum, 380ACP and more

The 38SUPER 627 as it shipped from the factory may or may not chamber the tapered 9MM Parabellum cartridge.

If it does not, a quick run through with a 9MM Parabellum finishing reamer will do the trick

Lou_the_welder · #6 08-22-2018, 06:20 PM

Comparing the same weight and powder on a 9mm and 38 super. This case 115gr and bullseye powder. At Max.
9mm= 31,700 c.u.p. pressure
38 super=31,300 " "
9mm 1184 fps
38 super 1182 fps

.....

I would say it is safe to use 9mm in a 38 super cylinder; if said cylinder was reamed to accept 9mm.
38 super is a straight walled cartridge. 384" across.
9mm case measure. 391" before Rim and .380" at bullet

Sent from my SM-N950U using Tapatalk

AveragEd · #7 08-22-2018, 06:44 PM

I have to ask why the preference for the 9mm? I have two .38 Supers and love them. As far as accuracy is concerned, you don't see many 9s at bullseye matches; Supers a-plenty though. And it seems like everybody has a 9mm, especially the younger crowd. I like the uniqueness of the Super.

Finally, the PC 627 in .38 Super should be worth more than the same gun in 9mm. I wouldn't give converting it a second thought.

Ed

BlackTalonJHP · #8 08-22-2018, 06:56 PM

If you're going to cut a .38 super cylinder for 9mm you might as well convert an ordinary .357 mag revolver to 9mm. I don't see the need to start with a .38 super revolver.

nola000 · #9 08-28-2018, 09:39 AM

Quote:

Originally Posted by robertrwalsh

Not physically possible. 9mm cartridge is about 0.004 wider at the base than .38 super. Will almost certainly not chamber, at least it shouldn't. If it does, something is wrong.

This is what I had always assumed as well but I opened my research back up when this particular piece came available to me at a nice price. I read that some people were able to chamber 9mm in theirs. Maybe these were worn chambers, as you indicated.

nola000 · #10 08-28-2018, 09:45 AM

Quote:

Originally Posted by colt_saa

Welcome to the Forum

The 38SUPER 627 as it shipped from the factory may or may not chamber the tapered 9MM Parabellum cartridge.

If it does not, a quick run through with a 9MM Parabellum finishing reamer will do the trick

Great info! Thanks.

I figured loose tolerances were to blame for the inconsistent feedback I was getting on this particular question.

Even better to know that its a simple affair to fit the chambers for 9mm.

nola000 · #11 08-28-2018, 09:50 AM

Quote:

Originally Posted by AveragEd

I have to ask why the preference for the 9mm? I have two .38 Supers and love them.

Ed

Ammo selection and price. Also, I have other pistols in 9mm. Of all my firearms I have 12ga., 9mm, .22 LR and .32 ACP. I didnt want to add yet another caliber to the confusion.

Quote:

Originally Posted by AveragEd

I like the uniqueness of the Super.

I agree. .38 Super is a cool round. I like unique too just not in firearms.

nola000 · #12 08-28-2018, 11:11 AM

Quote:

Originally Posted by BlackTalonJHP

If you're going to cut a .38 super cylinder for 9mm you might as well convert an ordinary .357 mag revolver to 9mm. I don't see the need to start with a .38 super revolver.

I think Im going to to look into this.

Couple of things Im noticing looking at this.

1. For .357, cylinder-to-frame gap would need to be, at a minimum, 1.52mm(0.06") based on rim thickness. For 9mm it would be a minimum of 2.17mm(0.085") to include both the 'rim' as well as the width of the 'extractor groove' formed in the case just above the 'rim' where the 'moon clips' would hold the rounds. Do most S&W .357s have enough cylinder-to-frame gap too allow for that 0.65mm(0.026") difference?

My Taurus 905(9mm J-frame revolver) measures 2.14mm(0.084") cylinder-to-frame gap in full lockup but the moon clip that the rounds headspace off of is only 0.5mm(0.02") which is 0.4mm(0.016") less than the 'extractor groove' of a 9mm case which C.I.P. specs as 0.9mm(0.035").

If most .357s dont provide enough gap to make up the difference between the cartridges then I would have to shim the cylinder forward but then I would be concerned about cylinder-to-barrel gap.

2. Case body diameter. .357 is straight walled at 9.63mm while 9mm is tapered from 9.93mm to 9.65mm. Does 9mm drop into S&W .357 chambers without modification?

3. Bullet diameter. .357 is 9.12mm, 9mm is 9.03mm. Ive read that 9mm bullets are inaccurate out of barrels cut large enough of .357 rounds. Granted this was for one of those Taurus cylinder-swappable revolvers so that could just be Taurus being Taurus but Im wondering if the same could be said of ALL .357 barrels.

colt_saa · #13 08-28-2018, 01:28 PM

Quote:

Originally Posted by nola000

I think Im going to to look into this.

Couple of things Im noticing looking at this.

1. For .357, cylinder-to-frame gap would need to be, at a minimum, 1.52mm(0.06") based on rim thickness. For 9mm it would be a minimum of 2.17mm(0.085") to include both the 'rim' as well as the width of the 'extractor groove' formed in the case just above the 'rim' where the 'moon clips' would hold the rounds. Do most S&W .357s have enough cylinder-to-frame gap too allow for that 0.65mm(0.026") difference?

My Taurus 905(9mm J-frame revolver) measures 2.14mm(0.084") cylinder-to-frame gap in full lockup but the moon clip that the rounds headspace off of is only 0.5mm(0.02") which is 0.4mm(0.016") less than the 'extractor groove' of a 9mm case which C.I.P. specs as 0.9mm(0.035").

If most .357s dont provide enough gap to make up the difference between the cartridges then I would have to shim the cylinder forward but then I would be concerned about cylinder-to-barrel gap.

The cylinder needs to be machined for moon clips at the same time it is converted from 357 Magnum to 9MM Parrabellum

The moon clips sit BELOW the rear edge of the cylinder. The cylinder spacing in the frame window does not change for this conversion

Quote:

Originally Posted by nola000

2. Case body diameter. .357 is straight walled at 9.63mm while 9mm is tapered from 9.93mm to 9.65mm. Does 9mm drop into S&W .357 chambers without modification?

No a 9mm Parabellum should not be able o drop into a 357 Magnum chamber, but a 38 Super will drop in most of the time.

The 357 Magnum cylinder needs to have a 9MM Parabellum finishing reamer run through it.

While 357 Magnum ammunition can still be chambered and fired in the converted cylinder, if you are a hand loader you will not like the brass that comes out.

Quote:

Originally Posted by nola000

3. Bullet diameter. .357 is 9.12mm, 9mm is 9.03mm. Ive read that 9mm bullets are inaccurate out of barrels cut large enough of .357 rounds. Granted this was for one of those Taurus cylinder-swappable revolvers so that could just be Taurus being Taurus but Im wondering if the same could be said of ALL .357 barrels.

This is mostly untrue

Accuracy is mostly a function of proper bullet spin.

Bullet spin is caused by the rifling engaging the projectile

Most people forget that there is both a land and a groove diameter involved when they talk about bore diameter. What is actually measured when folks slug a barrel is the groove diameter.

The difference between the land and the groove is the depth of the rifling and what engages the projectile and causes spin. This difference is somewhere around .008" - .013" depending on the type of rifling and who did it

Image courtesy of Hand Gun Safety Course

Jacketed, plated and coated 9MM projectiles measure anywhere from .355" - "3565" depending on the manufacturer. There is still plenty of projectile for the lands to grab onto and get spin even in a .357" barrel.

I have been shooting 9MM projectiles through many different .357" barrels for several decades now.

The accuracy exception comes when we are discussing lead projectiles. For least amount of leading and therefore best accuracy the lead projectile needs to properly fit the barrel it is being fired from

JimCunn · #14 08-28-2018, 01:33 PM

For two of my 637-2s, I've had TK Custom ream two titanium .38+/.357 cylinders for 9x19mm and moonclips. Shooting 9mm, they are both far more accurate than I am, and will still shoot .38+ with or without moonclips. .357 cases will expand and stick.
My hunch is that .38 super in a reamed 9mm might also stick. Dunno for sure though.

Narragansett · #15 08-28-2018, 01:34 PM

"""Ammo selection and price. Also, I have other pistols in 9mm. Of all my firearms I have 12ga., 9mm, .22 LR and .32 ACP. I didnt want to add yet another caliber to the confusion. """

The confusion does not start until you have more than one of every caliber, then you get confused which one to shoot!

That is in the rule book somewhere. I forget which number it is.

nola000 · #16 08-29-2018, 11:50 AM

Quote:

Originally Posted by colt_saa

The cylinder needs to be machined for moon clips at the same time it is converted from 357 Magnum to 9MM Parrabellum

The moon clips sit BELOW the rear edge of the cylinder. The cylinder spacing in the frame window does not change for this conversion

Yeah Ive seen some like that. I had it in my head that the moon clips sit on top the cylinder as they do in my Taurus 905IB. Only the extractor is recessed into the cylinder on my 905.

Quote:

Originally Posted by colt_saa

This is mostly untrue

Jacketed, plated and coated 9MM projectiles measure anywhere from .355" - "3565" depending on the manufacturer. There is still plenty of projectile for the lands to grab onto and get spin even in a .357" barrel.

I have been shooting 9MM projectiles through many different .357" barrels for several decades now.

The accuracy exception comes when we are discussing lead projectiles. For least amount of leading and therefore best accuracy the lead projectile needs to properly fit the barrel it is being fired from

Wow. This has turned out to be a very informative thread. Theres a reason Ive been lurking here for so long. This has to be the best firearm forum on the web.

reccpd101 · #17 03-26-2020, 07:06 PM

I had Pinnacle Gunsmithing take a spare L frame cylinder and convert it for moon clips and his special cylinder that fires a 9x23, 38 Super, and 9x19 (9mm Luger). Google Pinnacle Gunsmithing and Pennsylvania to read about it on his website...

Pizza Bob · #18 03-26-2020, 07:45 PM

If that 627-4 PC is really cheap, maybe you should buy it and flip it to finance a 929 or a 627 .357 mag conversion.

Just a thought.

Adios,

Pizza Bob

AlHunt · #19 03-26-2020, 08:10 PM

Use the savings to buy a reloading setup and reload the 38 super. Then you'll be more ammo self sufficient the next time we have a run on ammo.

JimCunn · #20 01-31-2021, 02:08 PM

Aren't SAAMI specs for barrel land and groove diameter identical for .38Sp, 9mm, and .357Mag?

AveragEd · #21 02-01-2021, 08:14 AM

Without actually checking I'm going to say they aren't. Bullet diameter for 9mm is .355", .38 Super is .356" and 357 is, well, .357". I would speculate that .355" bullets through a .357" barrel would lose some accuracy.

Having said that, I have shot .355", .356" and .357" bullets of the same weight through my .38 Supers with very similar accuracy BUT they were all cast semi-wadcutters. The results with jacketed bullets might well differ.

Ed

steelslaver · #22 02-01-2021, 11:34 AM

K frame 38 special cylinder modified to fire 38 special or 9mm in full moon clips

the 38 special rims uses the outside ledge to hold correct head space. The 38 brass swells a bit at the base but can be resized. I doubt that except for experimenting I will fire many 38s in the 2 cylinders I did this to. I have plenty of 38 and 357s to have any need to. I have never owned a 9mm, had the cylinders and a 327 mag reamer coming from 4DReamerRentals so had a 9mm reamer sent along with it. I might find some cheap 9mm ammo someday. I had to go find the empty brass just to check the setup out.

steelslaver · #23 02-01-2021, 08:22 PM

PS The only place I have found any 9mm clips to fit a K frame Smith is TK Customs and they are not cheap.$75 for 10. If you knew someone with a small water jet they would be easy to make. Machining them would suck IMHO

JimCunn · #24 02-04-2021, 09:44 PM

I wasn't referring to bullet diameter- I was referring to Saami specs for BARREL land and groove diameter. Based on the published information I've seen, they seem to be identical for the three calibers. Therefore, no impact on accuracy.