Has it been determined if this gun is .45 Super safe?

[jonsidneyb]

Has it been determined if this gun is .45 Super safe?

[R Dub]

Yep. http://www.hs2000talk.com/viewtopic....0734f364d59c15

[Sandy]

Well, I went back and read that linked thread. Nothing in that thread that would indicate that Springfield has an opinion about .45 Super, just some opinions of consumers, based on their estimation of how "beefy" the XDs are.

[Arkansas]

I am confident that the XDACP will handle Super after my discussions with SA and reading other posts. I am just waiting on the following drop in parts to hit the market:

1. A 5" barrel to get full 45 Super performance out of my Service.
2. A new guide rod and spring system so I use a heavier spring.

[murphyslaw]

the xd 45 acp is rated for +p. I'll try and find where i read it. think it was a SA catalog err something of that sort.

[AKM]

Originally Posted by Sandy

Well, I went back and read that linked thread. Nothing in that thread that would indicate that Springfield has an opinion about .45 Super, just some opinions of consumers, based on their estimation of how "beefy" the XDs are.

There have been at least 2 different answers from SA, but I think the most correct answer is "Sir, I simply can't tell you to shoot 45 SUPER in this gun because we haven't officially tested it." This is a paraphrase from a phone conversation, but I'd call that the truest answer we're going to get from SA on the issue.

There seems to be a trend to treat the Super as some kind of basement hot-load. It is anything but. It is merely bringing the 45ACP cartridge up to a normal operating pressure for auto pistols built with modern steel. The specs for 45ACP were set 100 years ago and were low even then.

Is the XD45 safe with Super? I am confident that it is. The Super operates at 28kpsi max. Standard pressure 9mm has a max pressure of 35kpsi. NATO spec (+P) for the 9mm is 38.5kpsi. So will the XD45 safely handle a pressure that is 10.5kpsi lower than a cartridge we KNOW is safe? It's a no-brainer. Super is downright WEAK in comparison to 9mm+P in terms of pressure.

Is the gun designed to take extended use with Super? No. The Super was simply not considered one way or the other. But consider that the peak thrust on the slide of 45Super is virtually identical to that of standard 40S&W and the Super doesn't look so "super".

How will it handle extended use with Super? Remains to be seen. But with the correct mainspring I have no doubt it will handle it with ease. (As to whether the stock spring is adequate, that's another discussion.)

[mullanman]

Question?


Why bother with the 45 Super?

[AKM]

Originally Posted by mullanman

Question?


Why bother with the 45 Super?

Answer:

600ft/lb of energy. 45 caliber.

Is it a good urban defense load? No. Way overpowered for that.

Is it a good hunting load? For some critters yes.

Is it a good backcountry defense load? Yes. Unless you're travelling where brown bears roam. In that case I'd want one of Linebaugh's creations.

I wouldn't bother buying a gun specifically for 45Super, but since I can shoot it in multiple 45ACP guns I already own, and I can reload it using the same equipment I use for 45ACP, it's pretty cool.

[mcb]

Say the 45 Super has pressures lower than a 9mm and thus is safe is bad engineering. As you go to a larger diameter bore the same pressure will cause greater hoop stress in the barrel. For example.

We have three gun barrels all have the same wall thickness, for the sake of argument will say 0.100 inches thick. One is .355 (9mm), one is 0.400 (10mm) and one is 0.454. If we subject all of these to the same 35,000psi the hoop stresses in the three barrel that all have the same thickness are drastically different.

0.353 inch (9mm) bore, 0.100 inches wall thickness at 35,000psi will induce 62ksi of hoop stress.

0.400 inch (10mm) bore, 0.100 inches thick at 35,000psi will induce 70ksi of hoop stress.

0.454 inch bore, 0.100 inches thick at 35,000psi will induce 79ksi of hoop stress.

As you can see the same pressure induced a 27% increase in hoop stress in the barrel just going from 9mm to 45 cal. And that was while holding the wall thickness the same. Compare the wall thickness of a 9mm XD barrel to a 45ACP barrel. I believe you will see the 9mm barrel is thicker.

So even at the lower pressure of 28000 psi the 45 super may be producing stress in part above what it was ment for. Simple saying that since the 9mm version of the XD can take 35,000 psi it is not necessary safe to assume the 45 cal version can take the pressure. The dimension change require to chamber the 45 caliber round may cause 28000psi to exceed the yield strength of some part. Pressure is insufficient information you must study the stress and strain induced by that pressure before you can be sure its safe.

IMHO the 45 Super is a bad idea in general. Not all 45ACP can handle the 45 Super but all 45 ACP can chamber the 45 Super. Kaboom waiting to happen.

mcb

[AKM]

Originally Posted by mcb

Say the 45 Super has pressures lower than a 9mm and thus is safe is bad engineering. As you go to a larger diameter bore the same pressure will cause greater hoop stress in the barrel. For example.

We have three gun barrels all have the same wall thickness, for the sake of argument will say 0.100 inches thick. One is .355 (9mm), one is 0.400 (10mm) and one is 0.454. If we subject all of these to the same 35,000psi the hoop stresses in the three barrel that all have the same thickness are drastically different.

0.353 inch (9mm) bore, 0.100 inches wall thickness at 35,000psi will induce 62ksi of hoop stress.

0.400 inch (10mm) bore, 0.100 inches thick at 35,000psi will induce 70ksi of hoop stress.

0.454 inch bore, 0.100 inches thick at 35,000psi will induce 79ksi of hoop stress.

As you can see the same pressure induced a 27% increase in hoop stress in the barrel just going from 9mm to 45 cal. And that was while holding the wall thickness the same. Compare the wall thickness of a 9mm XD barrel to a 45ACP barrel. I believe you will see the 9mm barrel is thicker.

So even at the lower pressure of 28000 psi the 45 super may be producing stress in part above what it was ment for. Simple saying that since the 9mm version of the XD can take 35,000 psi it is not necessary safe to assume the 45 cal version can take the pressure. The dimension change require to chamber the 45 caliber round may cause 28000psi to exceed the yield strength of some part. Pressure is insufficient information you must study the stress and strain induced by that pressure before you can be sure its safe.

IMHO the 45 Super is a bad idea in general. Not all 45ACP can handle the 45 Super but all 45 ACP can chamber the 45 Super. Kaboom waiting to happen.

mcb

I was trying not to get too far into the physics, but...

You are correct that the hoop stress of the 45 is greater for a given pressure compared to smaller calibers. But compare the chamber of my Kahr 9mm (rated for +P) which is the same thickness at it's thinnest point as my XD45 barrel. Both are .090".

Hoop stress of the 9mm+P in the Kahr = 75.8kpsi
Hoop stress of the 45 Super in the XD = 70.3kpsi

I don't know what steel is used in the XD45 barrel, but I'm sure it's not weaker than that used in the Kahr barrel.

The better modern steels have a yield strength in the upper 100s and a tensile strength in the mid 200s.

I stand by my statement that 45 Super is safe in the XD.

As far as the Super being a bad idea in general, it's not like you can walk into wally world and buy Super by accident. The possibility of it finding it's way into weak old chambers is there but remote. Same applies to any modern pressure loads of older cartridges like 45 Colt and 45-70.