"normal" 10mm loads vs .40 +p+ almost the same?

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the count

the count

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just wondering if there is a noticeable difference with 10mm using normal/average reloads or if I get almost the same bang for the buck (pun intended) with a hot 40SW load? does not have to be a scientific comparison, just your personal opinion if you shot both.
 
Your question is impossible to answer. "+P+" just means in excess of the highest recognized +P pressure. That's not enough information to provide an answer.

But here are some things you might find relevant. The 10mm, by virtue of its greater case volume, will be able to produce X velocity at a lower peak pressure than a .40. In addition, the 10mm has a slightly higher peak pressure SAAMI rating. Both are generally safe within their SAAMI rated range. You will be out of SAAMI rated range sooner (at lower velocity) with .40 than with 10mm. However, based on the claims of THR'er Clark (IIRC), there is some evidence that .40 brass, with its small primer pocket, may be stronger than 10mm. If that's correct (and I express no opinion on the matter), then the brass won't be the limiting factor in driving a .40 to 10mm speeds. However, that doesn't tell you anything about the ability of a gun to withstand pressure. A gun built to run SAAMI .40 rounds may have a hard time with 10mm-grade rounds. Disclaimer: Always stay within published limits and/or ammunition manufactured by a reputable ammo maker.

What are you trying to accomplish?
 
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It's my opinion with a 180gr bullet you can achieve ~150 fps more in a standard pressure 10mm than a standard pressure 40 S&W. A +P 40 S&W should come close without blowing the limits out of the water... (although there really is no SAAMI recognized +P in 40 S&W) With a 35,000 PSI ceiling the 40 S&W is potent as is.
 
Of course, if you're ignoring SAAMI limits, why not load the .40 to 10mm length? Then it will do absolutely anything a 10 will do. After all, a .40 is a just a pre-set-back 10mm. ;)
 
Maybe. "Normal" 10mm could be the anemic factory loads that mimic the soft FBI loads that became the inspiration for the 40. Both would clock in at about 1000 fps at 180 grains.

But if you hand load a 180 grain 10mm load about 10% less than max, you should generate something north of 1100 fps, which will start to outpace the hotter 40 loads.
 
ATLDave said:
What are you trying to accomplish?
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Nothing in particular at the moment. More of a academic discussion. Judging by what has been posted so far a +P(+) .40 would be pretty close to a regular 10mm. I have a Glock 19 and 30 and was thinking of getting one more. Now leaning more towards a .40 as I have about 800 cases I have been saving up and zero 10mm.
 
I'm going to assume you are just referring to a really "hot" .40 S&W load since there is no "+P" or hotter (as previously mentioned). You may get numbers similar to factory 10mm, but I would think accuracy would suffer. The 10mm is certainly more versatile, but that doesn't mean it's for everyone. If you are just a casual shooter, the .40 will probably be more up your alley. The brass is cheaper and more available.

I go about nuts trying to track down all my 10mm brass, and as a result those guns don't come out as often as I'd like.
 
There are a lot of 10mm loads showing 180's @ around 1100-1150. Some of the hotter 40's from Buffalo Bore or DoubleTap will match or beat that. Same with some handloads. So basically yes.

Bear in mind that there are hotter 10mm loads that will shoot 180- 200 gr bullets up to 1300 fps. If you don't need that much speed there isn't much reason to own a 10mm. And I own one that I like.

I view my G-20 as my backpacking/hiking/camping handgun for bear country. I carry the 200 gr DT ammo @ 1300 fps for that use. If there is no threat from large predators then I'm perfectly content with 9mm, 40, or 45.
 
I reload everything I shoot and if the 10mm didn't throw its expensive brass in to the next county I would have had one a long time ago.
 
I reload everything I shoot and if the 10mm didn't throw its expensive brass in to the next county I would have had one a long time ago.
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EXACTLY why I got rid of my 10mm. Dont get me wrong its a great round and at times I wish I had one but I found myself worrying more about the brass than the enjoyment of shooting an awesome round.

Most factory 10mm ammo isnt much faster than 40 but get some boutique ammo or handloads, put a heavy recoil spring in your semi auto, and the 10mm is capable of some pretty impressive results.
 
Almost all the factory 10mm I've seen is anemic. With a stout pistol like a Glock or EAA Witness you can load up some really impressive loads with the 10mm. Of course like others have said, brass isn't easy to find and it definitely isn't cheap.
 
the count said:
I have a Glock 19 and 30 and was thinking of getting one more. Now leaning more towards a .40 as I have about 800 cases I have been saving up and zero 10mm
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Same situation here. I plan to get a Glock 20SF and use 10mm-40S&W conversion barrel to shoot 40 brass which I have plenty of.
 
You can match typical factory 10mm with .40 S&W standard pressure loads using Long Shot powder.
 
ATLDave said:
Of course, if you're ignoring SAAMI limits, why not load the .40 to 10mm length? Then it will do absolutely anything a 10 will do. After all, a .40 is a just a pre-set-back 10mm. ;)
Click to expand...
I have been doing some very limited experimentation with that, but not enough to have conclusions, and not at true 10mm power levels. Mostly I tried to see if accuracy and reliability would be OK when seating a bullet out far enough that the bullet provides forward case support so that the extractor isn't the only thing supporting the round against the firing pin strike.

Back to the original point: there's no such thing as a true +P spec for 40 S&W, so it's not really a defined standard.

I should add that I'm doing this experimentation with a steel framed 1006, not a polymer gun.
 
the count said:
Nothing in particular at the moment. More of a academic discussion. Judging by what has been posted so far a +P(+) .40 would be pretty close to a regular 10mm. I have a Glock 19 and 30 and was thinking of getting one more. Now leaning more towards a .40 as I have about 800 cases I have been saving up and zero 10mm.
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I understand having the brass already is convenient but I would not choose a pistol because I have the brass. Starline has new 10mm brass and at a fair price.
 
To me Hot does not mean +P or over published data. So, no the 10MM and 40 S&W are very different. I don't use some factory loadings as a test of a cartridges ability.
 
I have a fantasy of getting my 610-3 cylinder reamed out to accommodate 10mm mag but I haven't found someone to do it yet. Of course I haven't looked too hard but someday...
 
Keep in mind factory ammo is still loaded within SAAMI specs for that specific caliber regardless of how many "+" or "Ps" are on the label. The +P is mainly advertisement hype. A +P 38 won't ever truly compete with a 357mag and neither will a +P 40 compete with a 10mm.
 
2nd', there are a few calibers (.38 spl, 9mm, and .45ACP, IIRC) that do have a SAAMI-specified +P rating that is higher than the non-P ratings, usually by a couple thousand PSI. For those calibers, the +P means something specific - that the pressure is less than the SAAMI +P standard and (probably) above the standard pressure.

For calibers without such a SAAMI spec - like .40 - it's impossible to know what it means. Maybe it means that the round is beyond specifications. By how much? Who knows. Same thing a "+P+" for 9mm. That doesn't convey any specific information.
 
SAAMI sets the standards for +p ammo puts most about 10% over normal pressure. +p+ just means that the load is over +p, from a tenth of a percent over +p all the way to kaboom.

http://en.m.wikipedia.org/wiki/Overpressure_ammunition


http://en.m.wikipedia.org/wiki/.40_S&W

Lists max pressure for the 40 being 35,000 psi and a 180 going 1050fps.

http://en.m.wikipedia.org/wiki/10mm_Auto

Lists max pressure for 10mm being 37,500psi and a 180 (also a 200g) running at 1300fps.

I am sure a proof load in 40 would "beat" a safe load in a 10mm.
 
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SAAMI doesn't set +P pressure on most cartridges. Most calibers have ONE pressure limit. A round is either within that limit or not.

And, of course, while pressure is what makes the bullet go down the barrel, peak pressure isn't the determinant of velocity (total area under the pressure curve is). So, it's quite possible in many calibers to make an overpressure round (using a very fast powder in a large-case-volume caliber, for instance) that, if the gun survives, does not even equal the velocity of an efficiently-loaded non-+P round.
 
I yearn for the pre +P days.....when a cartridge was either over pressure or it was not.

Whoever came up with such nonsense had to be a liberal.
 
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