Possible to load a 10mm to fit a .40?

03 November 2006, 05:59

rebel102285

alright here is what i am wondering, and why i am wondering. In north dakota to hunt with a pistol caliber the case length must be .992 or larger (which the 10mm is). I have a beretta .40S&W and the case length on the .40 is .850 . I AM NOT LOOKING TO GET 10mm power out of my .40 i was just wondering if it would be possible to use 10mm brass and put the amount of powder i would use in the .40 I may have to seat the bullet a bit deeper ( .142 ) what do you guys think is it possible? I'd really like to shoot a deer with my .40 Thanks for any Responses.

Adam

03 November 2006, 06:14

CDH

In short, no. The case length is critical for proper function (headspacing) and using 10mm brass would require a 10mm length chamber, magazines, etc. You couldn't seat the bullets deep enough to work in 40S&W mags, and it wouldn't allow the action to close when chambered.

03 November 2006, 06:16

rebel102285

thanks guess ill just have to use something else.

03 November 2006, 22:06

tnekkcc

You could trim a 10mm case from .982" to .840" and use a 10mm case in a 40 S&W chamber.

But the 40 S&W case can take 55% higher pressure than the 10mm case, due to the large primer pocket in the 10mm.

quote:
10mm is registered at 37500 psi
40sw is registered at 35000 psi
---------------------------------
7.1% difference, advantage 10mm

10mm is registered at 1.260" OAL
40sw is registered at 1.135" OAL
------------------------------
11% difference, advantage 10mm

Given those constraints with a 4.6" barrel, we would expect at best

200 gr. XTP JHP
10mm 5.8 gr. Bullseye 1089 fps = 218 PF
40sw 4.3 gr. Bullseye 969 fps = 194 PF
------------------------------------------
12 % difference, advantage 10mm

135 gr. Sierra JHP
10 mm 9.3 gr. Bullseye 1496 fps = 194 PF
40sw 7.8 gr. Bullseye 1411 fps = 190 PF
-----------------------------------------
2% difference. advantage 10mm

With poor case support barrels and / or factory loads and / or published handloads that may be the end of the story.
But with custom handloads and custom barrels that do not leave the thin case wall of the cartridge case unsupported, then strength from the cartridge design comes into play.

The LARGE primer pocket on a 10mm is .2100" inside diameter.
The SMALL primer pocket of a 40sw is .1745" inside diameter.

The extractor groove of .335" makes the brass case wall .0625" thick in the 10mm
The extractor groove of .335" makes the brass case wall .08025" thick in the 40sw
----------------------------------------
28.4% difference, advantage 40sw

Extrapolating from the thickness, if the 10mm can do 37500 psi, then the 40 should be able to do 48000 psi. But in reality, the pressure required for primer pocket failure of these cartridges is much higher. A Glock 22 40sw with custom barrel and custom handloads can be much more powerful than the best that can be done with a Glock 20 with custom barrel and custom handloads. The difference is much more than 28%. This can be roughly explained with hoop stress:

[Max Chamber pressure] = (Max hoop stress in brass around primer pocket) [2 [OD - ID]]/ [ID]

H06 tempered C26000 cartridge brass max stress = 65,300 psi (initiation of yielding)

Max chamber pressure 10mm = [65,300 psi] [2[.335" - .21"]]/[.21"] = 77,738 psi

Max chamber pressure 40SW = [65,300 psi] [2[.335" - .1745"]]/[.1745"] = 120,122 psi
--------------------------------------
difference 55% advantage 40sw

The max chamber pressures are, in reality, less than that, because the stress on the brass is not only tangential to the primer pocket, but there is also an axial compression. Those stresses can be combined and calculated and gives answers that track experiments, but requires Von Misses calculations that are way hard.

04 November 2006, 04:14

rebel102285

No i couldnt just trim a 10mm case down in order to comply with state law it must be .992 or larger

04 November 2006, 04:34

fredj338

Sounds like you need a good magnum revolver, .41mag or .44mag or even the great old 45colt.

04 November 2006, 07:04

tnekkcc

quote:
Originally posted by rebel102285:
No i couldnt just trim a 10mm case down in order to comply with state law it must be .992 or larger

Put a 27/64" drill in a chuck and twist it in hand until the 10mm case will chamber.
Put a "Y" drill in a chuck and twist by hand until a dummy 10mm cartridge will chamber.

You will have irreveribly converted that barrel to 10mm.

I have done something similar for converting 9x19mm barrels to 9x23mm, and it works better than the Clymer 9x23mm reamer.

If you want hot loads in a 10mm, put 30-30 brass in a lathe and turn it down until it fits. Make the extractor groove shallow.

04 November 2006, 07:18

rebel102285

quote:
Originally posted by tnekkcc:
quote:
Originally posted by rebel102285:
No i couldnt just trim a 10mm case down in order to comply with state law it must be .992 or larger

Put a 27/64" drill in a chuck and twist it in hand until the 10mm case will chamber.
Put a "Y" drill in a chuck and twist by hand until a dummy 10mm cartridge will chamber.

You will have irreveribly converted that barrel to 10mm.

I have done something similar for converting 9x19mm barrels to 9x23mm, and it works better than the Clymer 9x23mm reamer.

If you want hot loads in a 10mm, put 30-30 brass in a lathe and turn it down until it fits. Make the extractor groove shallow.

thanks for the suggestion (which i dont really understand) but there is no way i am going to be putting a drill bit down the barrel of my beretta

04 November 2006, 21:54

muck

DO NOT under any circumatances put a drill bit into a barrel to"rechamber".

AGAIN UNDER NO CIRCUMSTANCES PUT A DRILL INTO A BARREL INORDER TO RECHAMBER.

To start a chamber reamer is a very precisly machined tool with a very specific shape/design.

Your rimmless cartridge headspaces on the step machined into the barrel by the reamer.
A drill bit has a slopped edge, there for no step/ledge to stop the cartridge from moving further into the barrel(headspace again).
Using a drill bit will at best leave you with an unreliable firearm, at worst a very dangerous gun.

muck

04 November 2006, 23:28

rebel102285

quote:
Originally posted by muck:
DO NOT under any circumatances put a drill bit into a barrel to"rechamber".

AGAIN UNDER NO CIRCUMSTANCES PUT A DRILL INTO A BARREL INORDER TO RECHAMBER.

To start a chamber reamer is a very precisly machined tool with a very specific shape/design.

Your rimmless cartridge headspaces on the step machined into the barrel by the reamer.
A drill bit has a slopped edge, there for no step/ledge to stop the cartridge from moving further into the barrel(headspace again).
Using a drill bit will at best leave you with an unreliable firearm, at worst a very dangerous gun.

muck

exactly what i was thinking

05 November 2006, 05:56

tnekkcc

I have chambered rifles, handguns, and shotguns with boring bars, drills, staight fluted .001" increment reamers, adjustable straight fluted reamers, solid pilot reamers, floating pilot reamers, separate throating reamers, emery cloth, mill bits, Scotch Brite pads, steel wool, Dremel Carbide bits, files, valve grinding compound, and combinations of these.

They all work, if you know what you are doing.

The internet has 5 Chicken Littles for every guy who knows what he is doing.

05 November 2006, 09:23

rebel102285

quote:

The internet has 5 Chicken Littles for every guy who knows what he is doing.

You said it

05 November 2006, 10:26

Mark

quote:
Originally posted by tnekkcc:
I have chambered rifles, handguns, and shotguns with boring bars, drills, staight fluted .001" increment reamers, adjustable straight fluted reamers, solid pilot reamers, floating pilot reamers, separate throating reamers, emery cloth, mill bits, Scotch Brite pads, steel wool, Dremel Carbide bits, files, valve grinding compound, and combinations of these.

They all work, if you know what you are doing.

The internet has 5 Chicken Littles for every guy who knows what he is doing.

One wonders how we all survived back in the "old days"!

If you use your brain and really think things out, you can do a suprising amount of stuff with quite few physical resources.

Additionally, if you choose not to use your brain, all of the high-dollar gizmos in the world may not give you good results.

And ditto on the chicken little thing.

05 November 2006, 10:35

goneballistic

quote:
You could trim a 10mm case from .982" to .840" and use a 10mm case in a 40 S&W chamber.

I'm not a gunsmith, but I do remember reading that the large primer of a 10mm case would cause you problems. Drill bit conversions aside, the loading geometry of the .40 S&W calls for a small primer pocket. That's why even though the .40 S&W cartridge has the 10mm as it's parent case, the primer size is different. So cutting down the case is not only not a legal option for hunting, is not a technical option, either. Something about fixed ejectors impinging upon a larger diameter primer if live ammo is cycled thru the weapon.
Also, common sense would dictate that the longer cased cartridge (if loaded to the correct OAL) would not fit in the mag, auto load, or extract from your .40 S&W,... post any drillbit foolishness. Look at the size difference of a 10mm pistol when compared to a 40 S&W. There's a reason for that. Not to mention the lock/unlock times required for those two cartridges are also different.

06 November 2006, 00:45

tnekkcc

quote:
Originally posted by Mark:

One wonders how we all survived back in the "old days"!

If you use your brain and really think things out, you can do a suprising amount of stuff with quite few physical resources.

Additionally, if you choose not to use your brain, all of the high-dollar gizmos in the world may not give you good results.

Everything just keeps getting worse

When I read Macfarland's gunmsithing book, and he cuts a front sight dovetail on a barrel with a hack saw and a file, I realize what a pansy I am with a Bridgeport and a 60 degree dovetail cutter.

06 November 2006, 00:58

jeffeosso

40's will fit in a 10 (most of the time) and work, 10's are too long.

what state do you live in that wants a long case?

jeffe

06 November 2006, 21:45

larrys

Kansas requires a handgun cartridge length of 1.280", so I understand your plight. I solved it by buying a .375 and a .41 and a........, you get the idea.

No need to modify your Beretta, just an excuse to buy more guns!

06 November 2006, 21:56

rebel102285

Exactly I just sold the beretta and am building a 6.5 Grendel for my AR that should be some fun.

06 November 2006, 21:58

rebel102285

quote:
Originally posted by jeffeosso:
40's will fit in a 10 (most of the time) and work, 10's are too long.

what state do you live in that wants a long case?

jeffe

North Dakota

quote from gate and fence

Handgun (pistol or revolver or single shot) cartridge cases under .40 caliber must be at least 1.285inches in length and bullets must be at least .257 inches in diameter. Handgun cartridge cases of .40 caliber or larger must be at least .992inches in length. Muzzleloading handguns must be .50 caliber or larger. In addition, any centerfire handgun designed to fire a legal rifle cartridge shall be legal, except .38 S&W Special and 9mm Luger. All legal bow equipment as listed earlier in the deer bow season section shall be legal during the deer gun season. Fully automatic weapons, full metal jacketed bullets, or altered projectiles are prohibited.