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skygod1

40sw mixed with 10mm?

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While loading on my progressive press I had a couple 40s that made it through the process. Now sitting and thinking about it Im wondering if there would be any issues with going ahead and putting it through the gun?

Ive fired 40s in my 10 before, no big deal. And since its the same OAL as the rest of the 10s the powder chamber will still be the same size. Sort of like using a 10 that got trimmed to short. I cant think of any problem other than headspace and maybe extraction issues.

Whats some thoughts on this?

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Head space will off. Most likley nothing bad would happen but why take that chance....just pull them.

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If loaded with a 10MM class load you take a chance on overpressure. Not worth the potential problems.

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Is the web of 40sw brass different than 10mm? If I would trim 10mm to 40sw length would that be a problem with 10mm power loads? Just playing devils advocate. Physically other than length there shouldn’t be any difference. And loading to the same oal as 10mm should give identical powder chamber size. So I can’t imagine any difference in pressure. If I recall correctly 10mm is only longer to prevent loading into the 40sw guns.

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Is the web of 40sw brass different than 10mm? If I would trim 10mm to 40sw length would that be a problem with 10mm power loads? Just playing devils advocate. Physically other than length there shouldn’t be any difference. And loading to the same oal as 10mm should give identical powder chamber size. So I can’t imagine any difference in pressure. If I recall correctly 10mm is only longer to prevent loading into the 40sw guns.

If you seated a bullet into a 40 case at 10mm length there would be less neck tension on the bullet so the pressure would be different....maybe no higher but different. If your extractor can hold the case it will head space and fire, if the extractor cannot hold bad things can happen or nothing will happen.....not worth the trouble it could cause.

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Headspace isn't an issue ... I doubt 10mm Auto cases ever headspace off the case mouth; even new unfired 10mm Auto cases are shorter than the chamber minimum of .992".

 

If your progressive press was setup for 10mm Auto cases, which take a Large Pistol Primer, I doubt the 40 S&W cases, which take a Small Pistol Primer, would be properly primed and likely mis-fire.

 

The .40 S&W case has a heavier web than the 10mm Auto case due to the small primer pocket.

 

10mm Auto was developed before the .40 S&W, so the case length had nothing to do with preventing being fired in a .40 S&W auto. Also, 10mm isn't a .40 S&W Magnum as some would suggest...although the .40 S&W could be considered a 10mm Lite, which technically it isn't.

Edited by gjarcher

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I would be concerned, for the following reasons:

 

1. The 10mm operates at a higher pressure than the .40S&W. Whether your specific load does or not, I don't know.

2. The .40S&W has an issue being reloaded if it's been fired in an unsupported chamber. It weakens the area of the case that is not supported. If that area lines up with an unsupported area again in a .40S&W chamber, it could involve a catastrophic failure. Or, in a 10mm, where there is higher pressure, and a possibly weakened area of the case, it could fail.

3. Because of the liabilities involved, we (Armory staff/members) are not going to suggest that is contrary to conventional rules of shooting/reloading. All firearms should only be fired with ammunition designed and marked for that firearm. Loading ammunition not designed for it would violate the warranty of any/all firearms manufacturers that I know of, and probably all that exist. They make that statement for a reason. Without knowing you, how you reload, your specific reloading practices, and your firearm, we're not able to tell you if a specific action is safe in your firearm, with that ammunition. Without knowing that, we would refer you back to conventional rules of reloading and shooting, which is to only use ammunition designed for, marked, and within SAAMI spec for that firearm.

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Welcome to the Armory !

 

I agree it's not worth it.

Have not reloaded in a while, but it's just not worth it.

 

Have any kids the right age that you could pay a few bucks to sort them out? :laugh:

Or pay them per .40 S&W found...

 

"some of these are not like the others"

Have them wear rubber gloves if the cases have not been cleaned.

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I didn’t think about the neck tension, however just loading the 10mm I’ve noticed different pressures from case to case while taper crimping. I’m not looking for validation in my loading or shooting choices, I just wondered if anyone else had considered or experienced using 40 brass for 10mm loads?

It’s probably a good assumption that even shooting the 10mm that we don’t actually headspace, so shooting the 40 cases, which I have done many times in a 10 without issue, we wouldn’t headspace either.

I’ve been loading the 10mm for over 30 years now and have a modest supply of 10mm brass from long ago when they were designed for the small primer. Shooting 40’s out of a S&W 610 is just like shooting a 38 in a 357. I would say that it can be considered either a 10mm lite or the other way around as a 40 magnum. Same in any 10mm pistol.

That’s correct the 10 came first and the 40 was shortened to ensure that 10mm loads weren’t inadvertently used. Otherwise why didn’t the FBI just used reduced loads in the 10 as it was designed instead of having an altogether new caliber?

The disclaimer for the staff wasn’t necessary, we all know, or at least should know that we take our fates in our own hands when we reload for ourselves. Besides I don’t know of any manufacturer that doesn’t void their warranty if reloads are used in their guns, reasonable pressures or not.

I don’t know of anyone that has had any catastrophic failures shooting 40s in a 10mm, but that doesn’t mean it hasn’t happened. I have personally seen 2 in a 10mm from someone’s bad reloading practices. So I’m fully aware that care should be taken.

That being said I still can’t see any issues using 40 brass in lieu of 10mm if it’s seated to 10mm OAL and reasonable care is taken while loading. Really I ask myself why I would want to do this anyway, then I say why not? I still ask myself why 10mm brass is so much costlier than 40.

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I would pull the bullet on those....and not use them. One uh oh isn't worth it.

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