[2sofflead]

Does anyone know how close to 10mm performance the .40S&W can be loaded. Curious as same bullets can be used and case differences are relatively small. Thanks!:)

[strat81]

I can't give you specific numbers, but consider the difference between .38 Special and .357 Magnum. Small case difference, big difference in performance. Oh, and you need to check out DoubleTap Ammo for true 10mm performance. Most other brands pale in comparison.

[zxcvbob]

That depends on the gun.

I think Clark has done some research on this and 40S&W brass is stronger than 10mm brass because it has a small primer instead of large (therefore a thicker web). If I had a revolver that could shoot both and I wanted to hotrod it, I would use 40S&W brass with small rife primers. But if you do that in most automatics, you'll blow yourself up when the brass fails where it's poorly supported at the feed ramp.

[Zak Smith]

40SW has relatively limited powder volume available when loaded to spec length. Small initial volume causes high initial pressure, and small changes in OAL can have very large effects on initial and max pressure. In short, don't try to hot-rod the 40SW.

However, many IPSC/USPSA competitors load 40SW to a longer OAL (1.20 - 1.24" vs. 40SW spec max of about 1.14-1.15) for use in the SV/STI 2011-style guns. This volume reduces the initial pressure. But it is no longer really a 40SW since it is being loaded to 10mm length, and will not fit native 40SW platforms.

-z

[mavracer]

I can't give you specific numbers, but consider the difference between .38 Special and .357 Magnum. Small case difference, big difference in performance.
easy there I'm a 10mm fan but there's not nearly that much difference .357 works at ~twice the pressure of a 38 spcl. 10mm and .40 are about the same pressure.
3
.357 will nearly double the velocity of a .38.10mm is only good for ~200 fps maybe a little more with the heavy end of the bullets.

[LawDog969]

Here's some material that may help:
The .40 S&W semiauto cartridge has been thumping around since 1990. It got its big push when Smith & Wesson and Winchester proved that they could equal midrange 10mm performance with a shorter cartridge out of a smaller gun.
The .40 S&W is not just a shortened 10mm. The 10mm case is built to magnum specifications with a much heavier web, thicker case walls and uses a large pistol primer. The .40 relies on a small pistol primer for ignition. The .40 case measures .85 inch in length and should be trimmed back to .84 for reloading. It takes RCBS shellholder No. 27 and should be loaded to a maximum length of 1.135 inches according to the Speer Reloading Manual Number 12.
To say that the .40 has gained substantial respect is an understatement. It is the most successful new semiauto cartridge of the last 50 years and joins the .45 ACP and 9mm in the top-three list of the last century.

[rcmodel]

Re-read Zak Smith's post above.
That is the exact bottom line.

.40 S&W operates at 35,000 psi, and there is no extra case capacity to use slower powders.

10mm operates at 37,500 psi, and is better suited to more & slower powder, which equals higher velocity.
About 250 - 300 fps higher with heavier bullet weights.

If you need to get 10mm performance, you need to get a 10mm pistol.

http://i81.photobucket.com/albums/j219/rcmodel/KTOG/1224.gif
rcmodel

[R.W.Dale]

With the majority of big name factory ammo there is very little difference in 40 S&W vs 10mm

with handloads you're looking at about 200 fps on average between the two.

I think a comparison between 9mm +p or 357sig as more appropriate in describing the .40-10mm or even 30-06 vs 308. So for the most part 40 S&W will do 85 to 90% of what 10mm can do

[R.W.Dale]

drat! double tap

[Linear Thinker]

To answer the 2nd question - yes, same bullets can be used in both 40 and 10. I use Win 180gr JHPs for both, but my powder choices are different. In 40, I use Accurate #5 or Universal Clays, in 10mm I use Accurate #9. The difference in performance is ~200 fps, which is a lot.
LT

[JNewell]

In addition to case strength, I'd consider the chamber. You might be able to hotrod the .40 in, say, one of the S&W revolvers chambered for .40. I wouldn't do it in a Glock. (Still not a prudent idea...)

[Bullet]

Here is a comparison -

10mm Double Tap – 165gr - Golden Saber

Muzzle Velocity: 1425 fps
Muzzle Energy: 744 ft lbs
Measured from a Glock 20

10mm Double Tap –180 gr - XTP

Muzzle Velocity: 1350 fps
Muzzle Energy: 728 ft lbs
Measured from a Glock 20



40 S&W Double Tap - 165 Grain Gold Dot

Muzzle Velocity: 1240 fps
Muzzle Energy: 563 ft lbs
Measured from a 4.5" barrel
3.5" barrel - 1140 fps, 476 ft lbs
Glock 23 - 1200 fps, 528 ft lbs

40 S&W Double Tap - 180gr - Gold Dot

Muzzle Velocity: 1140 fps
Muzzle Energy: 520 ft lbs
Measured from a 4.5" barrel
3.5" barrel - 1050 fps, 441 ft lbs
Glock 23 - 1100 fps, 484 ft lbs