URBAN LEGEND - .40 to 9mm Conversion?

[SemperFi]

I know this will sound like a really silly question but here goes. Saw in another forum talk about the new S&W Shield in 9mm/.40 Cal. One comment was that he was going to buy a .40 and then only needed a 9mm Barrell and magazine to fire 9mm thru it. I've been debating on whether to get a .40 P30L or 9mm for a while - so this piqued my interest if at all possible for the same weapon models but with different calibers. I expect it could not be done due to differences in the recoil spring, slide tolerances, extractor etc. I've been an avid reader of the HK forum and if this was indeed possible I'm sure it would have been covered in here. Though a long shot I had to ask since it definitely would be nice to have two calibers for my P30 as well as future P30L almost for the price of one. If it sounds too good to be possibly true ....... ......

[dwillHK]

Generally, 9mm pistols aren't converted into .40 (and vice versa) because the breech face is part of the slide, and as the diameter of rear of the case is different between the calibers, so you'd need a new slide. Add in new barrel, spring, and mags to the cost of a slide, and you're essentially in for the cost of a new gun. About all the .40 is usually convertible to is .357 SIG, and that because the rear of the case is essentially .40 cal, which means you use the same slide, and usually the same mags and same recoil spring.

[Brownie]

Generally, 9mm pistols aren't converted into .40 (and vice versa) because the breech face is part of the slide, and as the diameter of rear of the case is different between the calibers, so you'd need a new slide. Add in new barrel, spring, and mags to the cost of a slide, and you're essentially in for the cost of a new gun. About all the .40 is usually convertible to is .357 SIG, and that because the rear of the case is essentially .40 cal, which means you use the same slide, and usually the same mags and same recoil spring.

+1. And this holds true to the P30 specifically which cannot be converted without also changing to a new slide.

[GarrettJ]

Generally, 9mm pistols aren't converted into .40 (and vice versa) because the breech face is part of the slide, and as the diameter of rear of the case is different between the calibers, so you'd need a new slide...

That is all true, and is the reason why a factory 9mm barrel won't work in a .40 caliber slide. However, there are some companies making conversion barrels that have a 9mm chamber / bore, but the hood is cut for a .40 caliber slide / breechface. The Lone Wolf conversion barrels for Glocks come to mind, but there are other companies make them as well.

The two LW conversion barrels I've used both worked just great. No feeding / cycling issues, even though the extractor and ejector were still set up for a .40 caliber cartridge head.

[USPc_4_life]

That is all true, and is the reason why a factory 9mm barrel won't work in a .40 caliber slide. However, there are some companies making conversion barrels that have a 9mm chamber / bore, but the hood is cut for a .40 caliber slide / breechface. The Lone Wolf conversion barrels for Glocks come to mind, but there are other companies make them as well.

The two LW conversion barrels I've used both worked just great. No feeding / cycling issues, even though the extractor and ejector were still set up for a .40 caliber cartridge head.

These conversions are notoriously unreliable and I have been told by LEOs they in some cases void any factory warranty a Glock has...and they also require different magazines...

The .40 to .357sig on a USPcompact is by far the easiest conversion and the best investment I have made for my pistol....the factory barrel from HK drops in and voila' it shoots from the same mags etc....but of course this works for me since I am not a big 9mm guy (to each his own though!)

In short the answer is NO they don't work and NO amount of engineering and promises will change the physics involved...which seems like a valid excuse to buy two HKs! One in .40 and one in 9mm!!

[GarrettJ]

These conversions are notoriously unreliable...

All you forgot was to start with "My buddy at the gunshop read it on the internet, so it must be true."

...and I have been told by LEOs they in some cases void any factory warranty a Glock has...

Why would a police officer be an expert on a private company's warranty policy. If you are worried about Glock's warranty, ask Glock - not your local Barny Fife.

and they also require different magazines...

Yeah - and the same holds true if you swap the whole top end, or get a 2nd gun as you suggest. So what?

The .40 to .357sig on a USPcompact is by far the easiest conversion and the best investment I have made for my pistol...

That's great. It is an easy conversion, and I'm glad it worked out for you. While it is a viable option, that wasn't the question.

In short the answer is NO they don't work and NO amount of engineering and promises will change the physics involved...

Please help us understand what physics you are referring to. Physics relates to mass, momentum, spring rates, etc. As far as I can tell, the barrels, slides, and other parts of a 9mm Glock or USP are essentially the same weight and size as their .40 caliber counterparts, and use the same springs. So if you put a 9mm conversion barrel in a .40 slide, the same physics apply as when shooting a 9mm barrel in a 9mm slide. So please enlighten us as to what you are referring to.

I posted above that both of the conversion barrels I bought dropped in and worked 100%. That doesn't sound like something that doesn't work. That's my personal experience. Do you have any actual experience with a conversion barrel, or are you just parroting what your cop / gunshop / internet commando buddy told you?

The barrels I have are for a Glock 35 (longer slide) and a Glock 27 (subcompact). Not only that, but I have the extended threaded barrels and shoot them with suppressors attached. If anything, these would make the gun / barrel less reliable if everything isn't set up correctly. I'm using factory recoil springs, and triggers. The only thing different is the barrel, can, and magazines. And in spite of what you claim, they still work just fine for me.

So again, what's you actual experience with them?

[USPc_4_life]

All you forgot was to start with "My buddy at the gunshop read it on the internet, so it must be true."


Why would a police officer be an expert on a private company's warranty policy. If you are worried about Glock's warranty, ask Glock - not your local Barny Fife.


Yeah - and the same holds true if you swap the whole top end, or get a 2nd gun as you suggest. So what?


That's great. It is an easy conversion, and I'm glad it worked out for you. While it is a viable option, that wasn't the question.


Please help us understand what physics you are referring to. Physics relates to mass, momentum, spring rates, etc. As far as I can tell, the barrels, slides, and other parts of a 9mm Glock or USP are essentially the same weight and size as their .40 caliber counterparts, and use the same springs. So if you put a 9mm conversion barrel in a .40 slide, the same physics apply as when shooting a 9mm barrel in a 9mm slide. So please enlighten us as to what you are referring to.

I posted above that both of the conversion barrels I bought dropped in and worked 100%. That doesn't sound like something that doesn't work. That's my personal experience. Do you have any actual experience with a conversion barrel, or are you just parroting what your cop / gunshop / internet commando buddy told you?

The barrels I have are for a Glock 35 (longer slide) and a Glock 27 (subcompact). Not only that, but I have the extended threaded barrels and shoot them with suppressors attached. If anything, these would make the gun / barrel less reliable if everything isn't set up correctly. I'm using factory recoil springs, and triggers. The only thing different is the barrel, can, and magazines. And in spite of what you claim, they still work just fine for me.

So again, what's you actual experience with them?

wow...somebody obviously needs to simmer down a bit! Now lets see here...1) read ANY GLOCK FORUM and you will see a lot of complaints about these conversions...its not closely guarded knowledge that they aren't 100% all the time (you state yours are fine which is NOT the norm)...
2)LEOs around here all have these things called "off-duty" guns...you know the ones they purchase themselves...and two of the LEOs I am talking about are FFL dealers too so you can say they have dealt with GLOCK on warranty issues before and I will bet the farm they are just as or better informed than 90% of the folks on any of the forums i frequent
3)the .357 sig conversion was to offer up that conversions do exist for some guns/calibers...
4)the physics I refer to is making a slide/extractor designed for a LARGER caliber work flawlessly on a SMALLER caliber--ie most of the issues I have WITNESSED FIRSTHAND were Failure to Extract issues...its essentially the same principle as trying to reload 9mm on my RL550--base plate needs changed because the casehead is different...Have I had hands-on experience? Nope--I own an HK because I want it to work flawlessly 100% of the time...if I want a different caliber (357 sig aside) I don't cheap out, I buy a new gun in a dedicated caliber--because I'm not an engineer and I don't want a gun that works "kind of"...if I did I'd go pick up a Hi-Point

If your experience differs then excellent! seriously mean that because sometimes it seems i never hear about a product that works only ones that don't

[Whoflungpoo]

Well, I'll avoid the pissing contest and just answer the OP

I have seen some manufactures and aftermarket companies make .40 to 9mm conversions and to my knowledge, only the Sig line has a few models that are made by the manufacturer. I could be wrong, but I am pretty certain that the P250, P226, and P229 have those abilities. Glock line has the aftermarket helping it out with the Lone Wolf conversions and its a mixed bag from my experience. Either it works reliably, or it doesn't.

As for HK doing this with the P30, I doubt it. P30's conversions aren't in high enough demand for the aftermarket or HK to make at this time.

As mentioned before the only slide barrel combo that works on an HK is the .357 and .40 slide barrel.

[jpgeorge]

Just changing the barrel is scary.

I purchased a complet USP40f upper. It slaps onto my USP9f and functions flawlessly.

Dual wield.

[rugerman21]

I am far from an expert but I can speak too the Glock .40 to 9mm conversion. I have a full size Glock and I purchase a Lone Wolf 9mm barrel for it on the recommendation of another Glock owner. It shoots wonderfully and consistantly and accurately. In fact is is more accurate than the factory .40 is. Perhaps that is because the reduced re oil between the .40 and 9mm or perhaps the barrel quality of the Lone Wolf. I am sure I do not know, but my personal experience has been very good. I can neither agree nor dis-agree with anything that has been said just stating my own experience. I will also be adding a .357 Sig barrel to my HK USP in the future I hope my experience is at least as good as the Glock has been, only since it is an HK it will be I am sure...haha Just Saying..