Home Forums Hunting & Shooting Handguns .45 vs 10 mm

JOG, is correct. Bolt thrust and pressure are both key components and both must be acounted for in a design. The 10mm loaded to the same pressure as a 45 ACP will have less bolt thrust. Because of the smaller diameter case

10 and 45 loaded to the same pressure don't have the same momentum comparing apples and oranges again. The 45 doesn't need a locked system, however the spring system may require 3 people to operate. several designs in the last 30 years, but non caught on. High PRESSURE is what needs locking systems so the pressure has time to fall off before opening goes for rifles and pistols. If in doubt stick your thumb over the cylinder gap on a 44 mag or 454 next outing. Even though a 1911 has 3 locking lugs the total area used is only about 50%.

Then why don't the .22 LR, .25 ACP, or .380 Auto need a locking system? All three have more pressure than the .45 ACP.

You're right in the respect that one of the functions of a locked breech is to delay opening until the pressure subsides. The other function is to retard slide velocity by adding barrel weight at the start of the recoil cycle when the recoil spring is still semi-relaxed. By the way, one blow back design that caught on (sorta) is the Hi-Point and they did it by increasing slide mass.

However, it isn't pressure that moves the slide. If you want to call it "momentum" that's fine with me.

There are other factors that go into bolt thrust as well, such as cartridge shape, and the condition of the chamber. Take a straight walled cartridge for example, often those cartridges exert little to no �bolt thrust� at all. PO Ackley proved this when he shot a .30-30 AI in a model 94 Winchester without a locking block; no problem at all.

Now do the opposite, and have a radically tapered cartridge and see what you get. The bolt thrust of a 9mm Luger is far greater than that of a .38 Super even though the .38 Super is a more powerful cartridge. That�s because of the sharp taper of the 9mm.

I point this out to call attention to the fact that there is no ONE issue. It STARTS with pressure, and then things expand beyond that depending on a whole lot of things. To make a singular statement that everything is about pressure is a faulty mindset. How is that pressure applied, what are the effects, how do you want to control that pressure. These are things that determine how arms are designed. Pressure is but a starting point.

Kevin, I don't disagree, but PO Ackley's test only determined the force wasn't directed to the bolt - not that the force didn't exist.

That's one of the reasons "bolt thrust" is a crappy term. Newton's laws of motion prove the forces counter to the bullet's acceleration must occur, but the variables you mention show we can't be sure where they will be directed.

You're going to have to explain this one further because I'm not seeing how this works. The pressure in the case exerts a force in every direction. It pushes on the back of the bullet so it goes out the barrel. It pushes straight back on the case head causing the events which make the gun cycle.

If the cases are absolutely straight wall, the forces acting on the side of the case have no component operating on the same axis as the bullet or case head motion. If the case is tapered (narrower), there would be a component of force acting in the same direction as pushing the bullet, and this would act to OPPOSE the rearward movement of the case head.

So what is going on here as a result of the taper to increase the bolt force?

When the case wall is straight, the pressure pushing on the chamber is much greater than anything pushing forward or backward, so the case tends to cling to the chamber instead of back. The tapered case just decreases the leverage, and the shape causes it to push backwards; simple as that.

For that much, if you change "pressure" to "force", I agree. After that, I'm not so sure. Maybe it's a matter of friction. A straight walled case continues to drag along the chamber, whereas a tapered case "disengages" from the chamber as soon as it moves slightly rearward and fiction is no longer in play..

Exactly. My point is more about point out that there are few things that are absolute. Yes, the force is still there, but it isn't able to overcome the force pushing toward the head of the case. So while there is force on the head of the case, in essence, there is no force on the bolt face.

Again, the point is just that things are often much more complex than simple absolutes.

Correct.

pressure is a very specific term,-- of course other things come into play, but just as much gun design is so broad of a term its useless. its easier to hold pressure as the center of discussion than gun design, all models only highlight certain features. Here again you refer to pressure to explain the change in coefficient of friction, (brass rebound)and not gun design.
I prefer to use the amount of work done, or being able to be done by the amt. of energy stored in the charge, either expressed in thermodynamic units (easy to calculate the force) then integrated to get the work, excess of course is what you call " beating up the gun" rather than thrust or momentum. Using momentum has the advantage of using bullet mass variation to compare between calibers. Another fun way to "model" is in the molar concentration on the nitrates involved if you want to look at it on another level, (apply the gas laws).

If the chamber has any lube in it, then the friction is reduced and the case has less cling to it

Lotsa variables, also how smooth is the chamber. I believe there is an effect there for friction. I don't know how big it is, and I'm not convinced it's as big as Kevin says it is. But during the pressure spike after ignition, the case is also expanded a bit against the chamber.

My experience is that My S&W 57 6 inch .41 Magnum with 175 grain silvertip is about a 100 fps faster than my Glock 20 with the same bullet. As to the 10 mm having more energy at 100 yards than my .45 ACP at the muzzle: 200 grain JHP .45 ACP does 1190 fps from 5.5 inch revolver with max load of 12.4 grains Blue Dot, +P load, less than 23,000 psi. 10 mm 200 GR. HDY FMJ does 1172 fps, 8.2 grain Longshot, 23,900 psi according to Hodgdon Reloading. Granted, I used a revolver because I didn't want to install the spring set in a .45 ACP semi-auto but the difference isn't nearly as great as some suggest, with the same bullet weight.

The S&W M57 is going to lose a touch of velocity due to the flash gap, but there's around 2.5" more barrel length.


Same deal, except 2" more barrel length for the revolver.

Your comparing apples to oranges.

What ? The 41 Magnum only beats the 10mm w/ 175 gr. bullet by 100 fps. ? Sierra lists four powders that can push their 170 gr. bullet 1450 fps. in the 41 Magnum. Never saw a load that developed over 1300 fps in the 10mm w/o excessive, tested pressures.
Lots of data shows the 41 Magnum at 1400 fps. plus with 210 gr. bullets. Good luck trying to get that from the 10mm with a 200 gr. bullet.
Likewise I have no data, and that includes +P data, that gives a .45 ACP load anything much over a 1000 fps with a 200 gr. bullet.
BTW, all of my data that shows the 10mm doing 1150-1190 fps with a 200 gr. bullet is right near maximum pressures.
I might also add that the 200 gr. Hdy XTP in 10mm has an SD of .179 and a BC of .199. The 45, 200 gr. XTP has an SD of .140 and a BC of .151. E

Norma had at least two.

Buffalo Bore has a 180 going 1350: http://www.buffalobore.com/index.php?l=product_detail&p=114

So does Double Tap: http://www.doubletapammo.com/php/catalog/product_info.php?cPath=21_25&products_id=122

And, DT has another 180 at just over 1300, too: http://www.doubletapammo.com/php/catalog/product_info.php?cPath=21_25&products_id=381



1400+? Nope.

Again, Norma had the 200s doing 1300.

Double Tap has 200 WFNGCs at 1300 (http://www.doubletapammo.com/php/catalog/product_info.php?cPath=21_25&products_id=105), 200 JHPs at 1250 (http://www.doubletapammo.com/php/catalog/product_info.php?cPath=21_25&products_id=40), and 230s at 1120 (http://www.doubletapammo.com/php/catalog/product_info.php?cPath=21_25&products_id=158).

Buffalo Bore has 200s at 1200 (http://www.buffalobore.com/index.php?l=product_detail&p=113) and 220s at 1200 (http://www.buffalobore.com/index.php?l=product_detail&p=219).



Again, check Buffalo Bore for 200s at 1000+, and Double Tap for 230s at 1000+.



I'd hazard a guess that either of those two companies have better pressuring testing equipment. Just a hunch...



Yep.

There's no contest here the 10mm is superior to the .45 acp..

Depends upon the intended use.

In the .41 mag, with 210 grain XTP bullets over Lil'Gun Hodgdon shows a starting load making 1505 fps with the starting loads, and 1626 fps at max, with 29,900 c.u.p.

That's probably out of a pressure barrel, and a real world revolver would lose some velocity out of the barrel cylinder gap, but in my own experience I saw 200's run in the high 1400's out of an 8 & 3/8 M57. I'd wager a 200-220 gr Keith style bullet would do a little more.

I like the 10mm, have two of them, and someday might tinker with a M610 revolver, but the 10mm is not a .41 mag.