Can a 9mm be fired from a 40 S&W?

SteveF · Nov 28, 2022

If someone had asked me this question I would have said "I seriously doubt it". But since this happened 20 feet in front of me - here you go.

My buddy wanted to fire a few rounds from my Glock in 40 S&W. While I wasn't looking he loaded some nice new shiny jacketed semi-wadcutter 40 S&W rounds from the box. For some reason he also grabbed two not so shiny, round nosed 9x19 that were loose on the table. He fired the gun and all was fine until the first one didn't eject properly and "gave a big spark". I assumed it was just a new gun needing more break-in rounds. The second had a nice primer strike but failed to fire. It was when picking up the brass that I realized what he had done.

Learn something new every day.

DrHook · Nov 28, 2022

"fire forming"...

akajun · Nov 28, 2022

yep, used to happen all the time when my Dept issued 40's and 9mm, your choice. doesnt hurt the gun, does blow out the brass and can let a lot of gas escape towards the shooter.

john.k · Nov 28, 2022

The extractor holds the rim securely enough for the primer to fire.

wesg · Nov 28, 2022

john.k said:
The extractor holds the rim securely enough for the primer to fire.

Isn't that how a match 45 is headspaced?

GGaskill · Nov 29, 2022

Doesn't surprise me. 9mm and .40 S&W are close enough in size that I always pick up few .40's while shagging 9mm.

Scottl · Nov 29, 2022

"while I wasn't looking"

Any time I'm dealing with anyone other than an experience shooter I know I can trust I watch them like a hawk. I load the magazines, and they don't handle any equipment unless I'm right there watching ie acting as a range officer.

That could have had disastrous results and it being your gun you could have been liable for damages or injury and the clubs I belong to will discipline a member for failure to supervise guests.

nuff said

standardparts · Nov 29, 2022

SteveF said:
If someone had asked me this question I would have said "I seriously doubt it". But since this happened 20 feet in front of me - here you go.

My buddy wanted to fire a few rounds from my Glock in 40 S&W. While I wasn't looking he loaded some nice new shiny jacketed semi-wadcutter 40 S&W rounds from the box. For some reason he also grabbed two not so shiny, round nosed 9x19 that were loose on the table. He fired the gun and all was fine until the first one didn't eject properly and "gave a big spark". I assumed it was just a new gun needing more break-in rounds. The second had a nice primer strike but failed to fire. It was when picking up the brass that I realized what he had done.

Learn something new every day.

Would suggest you and your 'buddy' stay away from firearms before someone gets hurt or killed.
Irresponsible moron move that can result in making lawyers rich and raising costs for firearm and ammo manufacturers.

MilGunsmith · Nov 29, 2022

We had an accident to investigate with .40S&W and .45ACP. The police department was training with a .45ACP blowback subgun and .40S&W pistols. All the magazines were being loaded in one location. The first burst was fired, going to fire the second burst , shooter got a click no bang. He performed immediate action pulling, the bolt to the rear where it locked, saw nothing ejected and an empty chamber. Upon firing the next round the subgun blew up. When we got the gun to investigate, the first thought was a squib load, but the shooter had only a click with no bang. I put a borescope in the muzzle end of the barrel and saw a base of a cartridge case. The borescope from the breech showed a bullet base. As the barrel was destroyed, we decided to section the barrel. There was a .40S&W case lodged in the barrel with a .45ACP bullet behind it. The theory was that a .40S&W got loaded into the .45ACP mag and upon firing the first burst got pushed into the barrel. The second burst fired the round in the barrel blowing everything up. I will look thru my old files for the pictures.

SteveF · Nov 29, 2022

Scottl said:
Any time I'm dealing with anyone other than an experience shooter I know I can trust

He is an experienced shooter which is why I didn't think I needed to load a mag for him. He made a dumb mistake, it happens.

SteveF · Nov 29, 2022

standardparts said:
Would suggest you and your 'buddy' stay away from firearms before someone gets hurt or killed.

And miss going again to the National Championship matches at Camp Perry? Don't think so.

standardparts · Nov 29, 2022

SteveF said:
And miss going again to the National Championship matches at Camp Perry? Don't think so.

You should be OK...range officers will hopefully keep you and your buddy safe.

GGaskill · Nov 29, 2022

Efficient organizations recognize the potential for these kinds of accidents and schedule their training such that the two types of ammo are not in use at the same time. Reminds me of the traditional 12/20 burst where a shooter accidentally drops a 20 gauge shell in the chamber of a 12 gauge gun, then loads a 12 gauge behind it and gets a kaboom.

scsmith42 · Nov 29, 2022

I've seen .380 and 9mm get mixed up before, but never .40 and 9mm. Thx for posting the pic.

Scottl · Nov 30, 2022

SteveF said:
He is an experienced shooter which is why I didn't think I needed to load a mag for him. He made a dumb mistake, it happens.

Sorry to sound a bit pissy about it but picking up unknown ammo off a bench and loading it without examining it is more than just a dumb mistake. A quick look at the head stamp would have shown that it was not a .40 cal.

I always load magazines, or any firearm, direct from the box. In my experience experienced shooters often get careless and make amateur type mistakes. Very often these result in a blowup and sometimes injury. When experience leads to a lax attitude it is time for a mental "re-training". I'm a trained RSO, was a SASS RSO before I let it lapse, and have acted as a range officer at various shoots. I also shoot muzzle loaders where things can go sour real fast if you don't pay attention. Firearms aren't toys and safety MUST be on your mind at all times,

Safety is no accident.

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