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"ah-lay-mahn"
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Discussion Starter · #1 ·
To all of you 45 Super and 10mm officianado's:

Firstly; I had a Glock 21 with LWD barrels, wolf guide rod and springs, sprinco, double mag springs, compensators, etc.. I have shot 45ACP, 45 Super and .460 Rowland from that pistol.

My question:

The max listed pressure for 10mm is 37,500 psi and the max listed pressure for 45 Super is 28,000 psi.

In my mind this says that shooting 45 Super should not require as stout of a gun as shooting 10mm does. If this is the case, then why is it suggested that a 45 ACP pistol be modified with a 24# RSA, a recoil buffer, etc. before firing 45 Super from it?

I completely understand the reason for having a barrel with a fully supported chamber, but considering that the max pressure rating for 45 Super is so much less than 10mm then why isn't the 45 Super a softer and easier shooting rig?

When I look at the pressure differential I see that my 45 caliber handgun should require a much less dramatic transformation than what is done for a 10mm handgun.

If a Glock 20 can handle most available loads without mods, then why can't a Glock 21, with a barrel change only, handle most available 45 Super loads?


 

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I am not an expert but I would think there is more to the equation that simply chamber pressure. I would think the case head thrust against the breech face would also come into play, ie the recoil forces of the cartridge against the slide as it relates to the diameter of the cartridge case pushing against the slide.

In shooting T/C Contenders for many, many years it has been accepted that case head thrust is a more important consideration as to whether or not a given cartridge will stretch a T/C Contender Frame or not. In regards to the Contender a .223 Remington is perfectly safe at 50,000 + CUP but yet the .30-30 Winchester if loaded above 44,000 CUP can and has stretched T/C Contender Frames. In the case of the Contender the diameter of the case head pushing against the breech face of the frame is a deciding factor.

I would think the same principal would apply to a semi auto handgun, but can be somewhat offset by the strength of the recoil spring.

Larry
 

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Let me start by saying I don't know what I'm talking about, but that won't stop me from taking a guess. :)

The larger the bore, the more surface area that is acted upon by pressure. If I had a cylinder that needed to hold 100 psi, and it's diameter were 3 feet, I'd need a much thicker wall thickness to contain that pressure than if it's diameter were less than an inch.

I would guess that barrel thickness, and bore are the culprit here.
 

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JABRONI AUTIST
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I'm far from an expert on anything, but I think that as long as you stick to what I call "regular" .45 Super, you won't need any upgrades really. The one thing I do know is that stock Glock .45 barrels have some pretty lousy chamber support, which isn't much of an issue when you're dealing with the lower pressure .45 ACP, but could bring about some concerns when pressures go up. Comparatively the 10mm G20 has better chamber support than the G21 .45 ACP.

As for and upgraded RSA, I've come to find that the stock Gen4 RSA on both the 20 and 21 work very well, even for heavy/warm 10mm and .45 Super. Compared side by side I can tell the stock RSA offers greater resistance than the aftermarket 24lb RSA I had been using.

Another issue is that a 21 is slightly lighter weight, which although small, will result in slightly higher slide velocity with warmer loads. This is likely a non issue when using "regular" .45 Super loads, but when the .45 Super is loaded to 460 Rowland levels (as in close to 40K PSI), you want every tool you can get to slow down the slide velocity and dampen recoil. The same reasons you would want to tame a 460 Rowland is why you would want to tame a warm .45 Super.

There are some online recoil calculators, never messed with them much really

http://www.beartoothbullets.com/rescources/calculators/php/recoil.htm?bw=&bv=&cw=&w=

Warm 10mm
180gr @ 1365 fps = 13 ft-lbs / 22 fps recoil velocity
200gr @ 1270 fps = 14 ft-lbs / 22 fps RV

"Regular .45 Super"
230gr @ 1100 fps = 14 ft-lbs / 24 fps RV

My warm .45 Super loads, come out as:
250gr @ 1275 fps = 23 ft-lbs / 30 fps RV
275gr @ 1200 fps = 23 ft-lbs / 30 fps RV
300gr @ 1150 fps = 25 ft-lbs / 31 fps RV

Here is another one

http://www.handloads.com/calc/recoil.asp

Comparing my warm 180gr 10mm at 1365 fps to a "regular" 230gr at 1100 fps in the .45 Super I get

Recoil Impulse in (lbs sec) =
1.28 (warm 10mm) vs 1.29 (Reg .45 Super)

Velocity of recoiling firearm (fps) =
23.49 (warm 10mm) vs 25.48 (Reg .45 Super)

Free recoil energy in (ft/lbs) =
14.99 (warm 10mm) vs 16.38 (Reg .45 Super)

Even the 10mm 200gr @ 1270 fps is less than the regular .45 Super.
 

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Glock Guy
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I would never shoot any 45 Super out of a Glock barrel. I went with LWD 5.2'' threaded.
 
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"ah-lay-mahn"
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Discussion Starter · #6 · (Edited)
I forgot to mention that what made me think about this is the relationship between 44 magnum pressure and recoil vs 45 colt pressure and recoil. I have read a few articles that state that a 45 colt, fires a 300 grain bullet, at the same velocity as the 44 magnum, with less pressure and felt recoil. I can't remember if there is more or less powder for either round. I thought maybe the same relationship might exist for 10MM and 45 Super.
 

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JABRONI AUTIST
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I like the .44 and have an uncle who has a number of .44's and I've shot a few of them. I personally started off with the .45 Colt and I've enjoyed it ever since, and at the same time I can see why people would like the .44. It similar type guns it seems to me that the .44 does have a more pronounced recoil than a .45 Colt loaded to similar levels.

Because the case capacity is greater in the .45 Colt, it takes more powder to get the same ballistics as you would in a .44. For instance say you have a .44 shooting a 300gr at 1,300 fps, if you put that same powder charge in a .45 Colt case with a .45 cal 300gr bullet, the .45 Colt will be slower and have less pressure. To get it up to the velocity the .44 is getting, more powder will be required in the .45 Colt to bring pressures up.

It is similar with the 10mm vs .45 Super/460 Rowland. I have a warm 10mm load that will shoot a 180gr XTP at 1,365 fps from a Glock 20 using 10.5gr of 800x. The same amount in a .45 Super with a 185gr XTP will be slower for sure because the Super/Rowland has more case capacity than the 10mm has, and would need several more grains of 800x to get to the same velocity.
 

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Like SDGlock23, I shoot my .45 Supers out of my stock G21 (with a 22lb spring to limit frame battering, I also use a 22lb spring in my G20 on my 10mm nuclear loads). I also shoot my .45 Supers out of my 1911s, again with a 22lb spring. No buffers, no comps, nothing else.

I use Starline .45 Super brass exclusively and so far have only gotten up to a little over 1100fps using a 230gr jacketed slug. I feel I can go higher than this number (at least with longish barrels) and will test them to find the limits of the powders I am using, but frankly 1100fps for a 230gr XTP is all I really need in my part of the world.

BTW, I find the 22lb ISMI spring on my G20 will work for most loads. I shoot 40S&W loads out of my G20 with the 22lb spring and while the brass stays pretty close, it cycles flawlessly. On my really hot 10mm loads, even with the 22lb spring the brass is flying 15+ feet. I tried the 24lb ISMI spring but didn't like the added felt recoil.
 
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