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

[the count]

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

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

As far as I am concerned that 250fps difference is really not a whole lot. And I doubt a bad guy will be able to tell the difference between those bullets! But I am not saying the 10mm is a bad thing ;-)

 

[918v]

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

Hodgdon lists 1159 FPS from a 4" barrel.

 

[SDGlock23]

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


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.

Wikipedia isn't a good source of info on many things, ballistics being one of them. For instance in no manual anywhere is a 200gr 10mm at 1300 fps within spec. Even the better powders struggle to beat 1200.

 

[SDGlock23]

I loaded for the 10mm for a long while but I got out of it. Brass cost and generally larger sized guns just didn't do it for me but the real kicker is how little difference there really is between it and the .40. Don't get me wrong, I'm not saying the 40 equals the 10mm in every way but when you really look, there's not a huge difference...although "huge" seems to differ between folks.

If you just look at much of the load data out there, the 10mm doesn't show to be much faster, and that's with it loaded to higher pressures and using a longer barrel 99% of the time compared to the .40.

Some won't agree with me here, but I think .40 brass is stronger than 10mm brass, the same as the 40K PSI rated 357 Sig. When the .40 was first introduced it was given the 35K PSI rating and early on there were a few issues with weak brass showing up, so basically the .40 was beefed up but the rating never changed despite this. Plus it's small primer pocket puts more material in the webbing of the case compared to the 10mm, which may not really be a significant boost, but more material means more support. To put it another way, .40 brass isn't any weaker than 10mm brass and is, in my eyes, a 40K cartridge like the 357 SIG. Others too have confirmed that the .40 can indeed withstand more pressure than the 10mm.

Whatever pressure the 10mm can handle, so can the .40 and then some. My reason with saying that is to make this point, if you used the same powder, the same bullet, loaded the 10mm and .40 to the same pressure and used the same length barrel, in most cases you would see less than 100 fps difference between the two. That's a fairly bold statement, but I feel it's absolutely accurate. (I'll post up a pic later to give an idea of what I'm saying).

I'm not convinced in the slightest that 100 fps (or lets say 75-125 fps to play it safe) makes any difference at all in performance. Pretty much with powders like Longshot and 800x and 3N38 for the .40 there's not much solid reason to buy a 10mm (well...that is unless you don't reload). My stock G35 will run a 180gr bullet to around 1,300 fps with the right powder, I don't need a G20 10mm to that.

Edit to add picture:


This makes a somewhat interesting point, at least I think it's interesting. This powder does well in both calibers as can be seen here, but as is with the 10mm loaded to higher pressure and using an inch longer barrel the difference is around 125-130 fps although the bullets are not the same design. I would say that if the pressures were made as close to the same as possible (assuming one had the equipment to test such things), in this case either dropping the 10mm 2300 PSI raising the .40 2300 PSI along with say chopping an inch off of the 10mm, the difference would be less than 100 fps, heck cutting off 1" of barrel alone would likely do that without messing with the pressure. Different powders vary but the differences seem fairly similar with other powders, and some like those from Accurate do seem to show more of a difference but I never could get claimed velocity with AA powders and the 10mm, nowhere near really. Just some food for thought.

 

[kerreckt]

10mm really starts to shine after 180grs. compared to 40S&W. At 200grs. it has 200+/-fps more than a 40S&W. Pretty much less than 100fps at 155grs. So, at the lighter weights it is as close they will ever get. To put it another way. There is 5%+/- difference at 155gr. and 20%+/- at 200grns. Even if you choose to overload the 40 to to get 10mm velocities, the 10mm will always have that extra capacity. I don't know what "+P" is. But whatever it is, if 40S&W can have it, so can 10mm and 40S&W can't keep up at the heavier weights. That's not to say that the 40S&W is anemic. It's just not a 10. This is what, I have discovered hand loading these two calibers.

 

[CPLofMARINES]

No, such animal as .40 +p or did somebody already say
that.

 

[jmr40]

Wikipedia isn't a good source of info on many things, ballistics being one of them. For instance in no manual anywhere is a 200gr 10mm at 1300 fps within spec. Even the better powders struggle to beat 1200.

That isn't from a manual or wikipedia. That is from my chronograph, 1315 fps actually in my gun.

http://www.doubletapammo.net/index.php?route=product/product&path=125_178&product_id=105

I don't know how they do it, but they do. And with no pressure signs. They are too expensive to shoot a lot, but I do keep a box for special occasions.

 

[Wreck-n-Crew]

Just a note for someone that is not aware of certain +p quirksressure doesn't equate to a set velocity even for the same bullet. Some hand loads, using the right powder, Can reach at or near +p velocities with standard pressures. FE the Corbon 115gr 9mm +P 1250 FPS while a hand-loaded 9mm Speer GDHP loaded with max load of 8.5gr of Blue Dot is rated @ 1258 FPS. Same Velocity, different pressures.

References:http://www.corbon.com/corboncart/dpx09115-20
http://www.alliantpowder.com/reloaders/recipedetail.aspx?gtypeid=1&weight=115&shellid=23&bulletid=25

This is repeatable under listed load data using different powders and with different calibers too.

How? The key is burn rate. Slower powders can continue to burn and create more velocity after bullet leaves the chamber. Faster powders generally create higher initial pressures and don't continue to burn and expand the same way ,the very thing that the slower powder uses to create that added velocity to the bullet after leaving the chamber.

Makes you question the +p reasoning doesn't it? IF higher velocities can be achieved with lower pressures then why not load with such powders? My guess is cost and powder attributes. Why use 8.5 GR of Blue Dot or 6.3gr of Unique (rated at 1244 FPS) when you can use 4.5 gr of Type X thereby reducing cost and increasing profit ? Maybe a cleaner burning powder as well ?

Then again Not all +p ammo is the same and some have higher velocities that can't be reached under normal pressures and in a sense the those are the ones worth paying for. It makes no sense to me that a high pressure round would produce velocities that can be found in standard pressure loads and if your going to go over pressure you should get enough velocity in compensation. After all that's why people buy +P right?

 

[ArchAngelCD]

No, such animal as .40 +p or did somebody already say
that.

Yeah I said that but it was back on the first page. Nothing wrong with repeating that important point.

 

[GLOOB]

The reason why there's no 40SW +P is because there are currently produced guns which cannot handle any more than the regular max pressure of 40SW. Many of the early 40SW handguns were built on regular 9mm frames and are already pushing the limits.

My G27 is an example. If I play even a little loose with top end load data, or if the recoil spring isn't replaced often enough, I can easily get failures to extract. If you tried to make +P 40SW ammo, it would not function in these guns.

So you're limited by the gun more than the case. That said, the hotter S&W factory ammo isn't all that much different than most factory 10mm. Defensive JHP ammo is probably better off at 40SW speeds than the 150fps or so faster 10mm loadings, anyway. The biggest difference in factory ammo is you can get 200 grain hard cast in 10mm.

If you reload, the difference might be much greater, but it depends on what will function reliably and safely in your particular gun.

How? The key is burn rate. Slower powders can continue to burn and create more velocity after bullet leaves the chamber. Faster powders generally create higher initial pressures and don't continue to burn and expand the same way ,the very thing that the slower powder uses to create that added velocity to the bullet after leaving the chamber.

Makes you question the +p reasoning doesn't it? IF higher velocities can be achieved with lower pressures then why not load with such powders? My guess is cost and powder attributes. Why use 8.5 GR of Blue Dot or 6.3gr of Unique (rated at 1244 FPS) when you can use 4.5 gr of Type X thereby reducing cost and increasing profit ? Maybe a cleaner burning powder as well ?

This is good and all, but peak pressure is not always what causes guns to malfunction. Sure, some guns might be so underbuilt that a little more peak pressure will stretch or blow the chamber or greatly accelerate locking lug wear. But most of the time, a locked breech semiauto is going to fail to extract and possibly suffer damage to the extractor and/or recoil spring before worse things start to happen. If you're already at your gun's limit, chasing increased velocity with a slower powder will still cause those failures, same as increasing the peak pressure would have.

Same thing for cast or plated bullets. They run at lower pressure for a given speed. But you can't beat jacketed bullet speeds by using cast bullets, at least not by anything worth mentioning out of a recoil operated (locked breech) autoloader. (You CAN in a revolver or a blowback pistol!) When you exceed the max bullet velocities for bullet weight, you will start getting those failures to extract, even though your pressures are below max (for jacketed bullets). Faster bullet = faster slide cycling = less time for the brass to retract from the chamber walls. This is why MAX pistol loads for cast bullets are topping out at 2/3 max SAAMI pressure, in many cases. If you want to try getting faster velocities, go ahead and play with overbook cast bullet loads in your locked breech semiauto. You'll see what I mean.

You can also think of it like this. A recoil operated pistol is limited to a certain maximum recoil that it can handle. And in most cases, this limit can be reached before the pressure ceiling is a significant concern. For practical reasons, it's much better if your gun starts to have extractions problems first, rather than immediately turning into a grenade. Most manufacturers have pressure tested their designs for at least 50% higher pressure than max SAAMI.

 

[mljdeckard]

For me, .40 is the last cartridge I want to start tweaking the pressure on. It is already a lot hotter than most other service cartridges, and has plenty of problems in its most popular gun. I would just get a 10mm.

 

[Wreck-n-Crew]

This is good and all, but peak pressure is not always what causes guns to malfunction. Sure, some guns might be so underbuilt that a little more peak pressure will stretch or blow the chamber or greatly accelerate locking lug wear. But most of the time, a locked breech semiauto is going to fail to extract and possibly suffer damage to the extractor and/or recoil spring before worse things start to happen. If you're already at your gun's limit, chasing increased velocity with a slower powder will still cause those failures, same as increasing the peak pressure would have.

Lower pressures equal lower forces where it counts. Pressures within SAAMI Specs will cause no more wear than any standard pressure factory round. The extra velocity is not equal to extra force on the chamber or firearm. Keep the pressure within SAAMI ratings and no additional wear is possible other than (to a minute degree) increased barrel wear. There is not a Velocity max by SAAMI for a reason, it does not produce premature catastrophic failures in firearms.

My point was not about chasing velocity, but marketing, profit and powder choices by manufacturers. Point being that Buffalo Bore has used the same method of using certain powders to get higher velocities without extreme pressures in some of their ammo while the mainstream ammo manufacturers go another route. Same thing for re-loaders using a powder that may be a little dirtier and a little more expensive to achieve better velocities without needing a +P rated gun.

 

[GLOOB]

Lower pressures equal lower forces where it counts.

Lower PEAK pressure just means lower peak force on the locking lugs and chamber. If your pistol wears out the locking lugs or chamber, then this will make a difference. I've never heard of a pistol wearing out its chamber.

Pressures within SAAMI Specs will cause no more wear than any standard pressure factory round.

False, false, and more false. Try making a cast bullet load using Unique or slower, at a SAAMI peak pressure of 35k psi. That will cause more wear (and malfunctions) on the gun than would occur by making a 36k psi jacketed round using bullseye or tightgroup. Wear on the gun is accelerated primarily when recoil is increased. Using slower powders to achieve higher velocities increases recoil.

The extra velocity is not equal to extra force on the chamber or firearm.

Not on the chamber, no, but it will increase slide velocity.

Keep the pressure within SAAMI ratings and no additional wear is possible other than (to a minute degree) increased barrel wear.

I'm not worried about wear. Primarily, you will run into function issues. Accelerated extractor and recoil spring wear can also occur, but if the round doesn't function then who cares?

There is not a Velocity max by SAAMI for a reason, it does not produce premature catastrophic failures in firearms.

I never said it caused catastrophic failures. A failure to extract is not catastrophic. And this only pertains to recoil operated firearms, ie locked breech pistols. There is no velocity max by SAAMI because all guns are different and max pressure is about as good a measure as any when standardizing ammo.

If there was a new powder that could make a 40SW load that pushes a 180 grain bullet to 1300fps without exceeding 35kpsi, that would be great. But it would not function in most 40SW locked breech pistols. And recoil would be horrific in the smaller platforms.

Think on this. When you do a .460 Rowland conversion on your 1911, do you put in a stronger barrel/chamber and beefier locking lugs? No. You add stronger recoil springs and a compensator. Do these modifications reduce or counteract peak pressure? No. They reduce slide velocity. If you fire .460 Rowland ammo out of a chamber-reamed but otherwise stock 1911 what happens? Does the chamber blow up? No. Do the locking lugs shear off? No. Do the cases fail to extract and your gun beat itself to death? Yes.