# Can i put a 9mm barrel in a px4 .40?



## STLNC3

Can i put a 9mm barrel in a Beretta Px4 storm full size .40 cal gun?

I have a M&P40c and with that i can just drop in a stock 9mm barrel and 9mm mags and shoot 9mm though it. saves a few bucks at the range that way. It is a .40 gun though, but the barrel can swap....

I just bought a px4 strom full size in .40 and was wondering if i could do the same.... Go buy a 9mm barrel and 9mm mags and run it through that gun..... 

If anyone has done this or has any links or helpful info, please pass it along.... Thanks much!

Love the px4 by the way, AWESOME GUN!!


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## TheLAGuy

Yeah I love mine in 9mm.... It's pretty danky isnt it?


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## STLNC3

yeah, its sweet! I just hope i can drop in a 9mm barrel and shoot 9s as well.... Hope someone has an answer


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## STLNC3

really? no one has an answer for this?


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## TheLAGuy

You need 9mm barrell and new clips right? thats it?


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## STLNC3

thats the question..... i would assume thats all you need, as that was all i needed for my Smith and Wesson M&P... im just hoping someone has done it and can tell me if it work or is possible


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## TheLAGuy

How much does it cost for the barrel and magazine?


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## STLNC3

Barrel, you could get for around 150... mags vary, i would say 30 or so. I have seen packs of 2 for like 45-50 though


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## thndrchiken

Yes you can, and they are magazines, not clips.


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## TheLAGuy

IM thinking of getting a Glock .40 and getting the extra barrel for 9mm, you know why?

Cuz I can!!! lol...


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## STLNC3

thndrchiken...... have you actually done this? or seen it done? Just dont want to do it and blow my hand off or ruin my gun.


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## thndrchiken

Yes I have, I have an M&P 40c, I regularly swap the 40 barrel to the 357 barrel and the 9mm for range work. I would however recommend getting 9mm magazines and not using the 40/357 magazines for 9mm. Especially if you plan on carrying in that configuration. The only difference in the slide is the cutout on the top is slightly larger for the 40 barrel compared to the 9mm barrel. No you won't blow your hand off.


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## STLNC3

I know i can do it on the M&P, I already have the two different barrels for that........ This is a Berreta forum and the question asked is about the px4 storm NOT the M&P or else the question would be in the Smith and Wesson forum....

So i assume, NO, you have not done it with the Beretta Px4 Storm?


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## AmericanVigilante

No you can't. The barrels have different O.D. sizes and it won't lock up with slide correctly. The 9mm slide is not only choked down around that smaller size, but the inside/underside of the 9mm slide is significantly machined out lighter to compensate for the lesser caliber recoil.


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## denner

AmericanVigilante said:


> No you can't. The barrels have different O.D. sizes and it won't lock up with slide correctly. The 9mm slide is not only choked down around that smaller size, but the inside/underside of the 9mm slide is significantly machined out lighter to compensate for the lesser caliber recoil.


Where did you get that information? As far as I've researched everything between the 40cal PX4 and 9mm Px4(full size and compact) is interchangeable except the magazine, barrel, and I'd recommend the 40 cal recoil spring. The barrels and locking blocks having the same dimensions except the inner dimensions of the barrels(not the outer dimensions), with the 9mm barrel being thicker and the .40 cal. barrel being thinner.

I believe you can obtain a 40cal vs 9mm extractor as well, but one extractor is described as working for both calibers as well as the locking blocks, etc....

I own a .40cal PX4 compact and a 9mm PX4 compact. I can assure you the barrels, slides, locking blocks, etc...... are perfectly interchangeable with the others slide and frame. Likewise the .40cal and 9mm PX4's have identical dimensions except for the inner barrel diameter....The slides are not machined out differently and one is not heavier or lighter than the other.

http://www.brownells.com/schematics/Beretta-/PX4-sid879.aspx


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## roguejesse

Brownells shows different part numbers for the Inox slides:

913-000-716WB 
Slide Px4 F Full Inox 40S&W
Mfr Part: JOPX4F40S

913-000-717WB 
Slide Px4 F 9Mm Inox
Mfr Part: JOPX4F9S

Also different part numbers for the G version slide:

913-100-845WB 
Slide Assembly, G Version
Mfr Part: JOPX4G40

913-100-846WB 
Slide Assembly, G Version
Mfr Part: JOPX4G9

The F version, only the .40 is listed.

913-100-796WB 
Slide Assembly, F Version
Mfr Part: JOPX4F40

While the recoil spring assemblies are different; when I purchased them from Beretta with steel guide rods. The .40 was listed for +P 9mm too.

Have you encountered any problems with your swap/interchangeability?

Thanks
Jesse



denner said:


> Where did you get that information? As far as I've researched everything between the 40cal PX4 and 9mm Px4(full size and compact) is interchangeable except the magazine, barrel, and I'd recommend the 40 cal recoil spring. The barrels and locking blocks having the same dimensions except the inner dimensions of the barrels(not the outer dimensions), with the 9mm barrel being thicker and the .40 cal. barrel being thinner.
> 
> I believe you can obtain a 40cal vs 9mm extractor as well, but one extractor is described as working for both calibers as well as the locking blocks, etc....
> 
> I own a .40cal PX4 compact and a 9mm PX4 compact. I can assure you the barrels, slides, locking blocks, etc...... are perfectly interchangeable with the others slide and frame. Likewise the .40cal and 9mm PX4's have identical dimensions except for the inner barrel diameter....The slides are not machined out differently and one is not heavier or lighter than the other.


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## ktfeich

I stumbled on this thread while looking for an extended barrel in .40 for my px4 (so if anyone knows where to get one, let me know)

But to answer the original question - no, you can't just put a 9mm barrel in a .40 slide and have it work. I have a 9mm px4 and I started with buying a .40 barrel which did not fit into a 9mm slide, I then bought a .40 slide which works perfectly on the 9mm lower but _will not_ accept a 9mm barrel - it's super loose in the slide. It is indeed a problem with the outer diameter of the barrel.

So to convert like that you need to get a compete slide. Used ones come up for sale every now and again. Brownells also has them.

If anyone is wondering about .45 conversions the answer is no as well - the .45 magazine does not fit into a 9mm lower. The slide does install and lock in spite of being a few millimetres longer and can even fire but you are limited to single shot. I suppose I will at some point in time get a .45 lower to see how it works the other way.

I would not trust what Brownells techs say about parts interchangeability - they were spouting complete heresy when I was trying to get parts to complete the .40 slide. They were telling me to get parts that were completely inappropriate according to the parts diagram (told me I needed DA/SA specific parts while I was very specific that the slide was DA only). Good thing they have the part diagram and an excellent returns policy.


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## denner12

ktfeich said:


> I stumbled on this thread while looking for an extended barrel in .40 for my px4 (so if anyone knows where to get one, let me know)
> 
> But to answer the original question - no, you can't just put a 9mm barrel in a .40 slide and have it work. I have a 9mm px4 and I started with buying a .40 barrel which did not fit into a 9mm slide, I then bought a .40 slide which works perfectly on the 9mm lower but _will not_ accept a 9mm barrel - it's super loose in the slide. It is indeed a problem with the outer diameter of the barrel.
> 
> So to convert like that you need to get a compete slide. Used ones come up for sale every now and again. Brownells also has them.
> 
> If anyone is wondering about .45 conversions the answer is no as well - the .45 magazine does not fit into a 9mm lower. The slide does install and lock in spite of being a few millimetres longer and can even fire but you are limited to single shot. I suppose I will at some point in time get a .45 lower to see how it works the other way.
> 
> I would not trust what Brownells techs say about parts interchangeability - they were spouting complete heresy when I was trying to get parts to complete the .40 slide. They were telling me to get parts that were completely inappropriate according to the parts diagram (told me I needed DA/SA specific parts while I was very specific that the slide was DA only). Good thing they have the part diagram and an excellent returns policy.


I don't know about a DA only slide, but the PX4 Compact in 40cal(DA/SA) can be converted to a 9mm pistol with just a PX4 Compact 9mm barrel and PX4 9mm magazine.

I can tell you and unfortunately I don't have access to calipers but the 9mm compact barrel has the same outer dimensions as the .40cal barrel including it's locking block cutouts.

The locking block in either 9mm or .40cal is interchangeable with the other.

Now with the fullsize and or the DA only slide, I may stand corrected. In other words you can go from .40cal to 9mm but not 9mm to .40cal in the compact.


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## ktfeich

Long time, but since someone from here asked me about the 45/9 compatibility I thought I'd update everyone on that subject:

You can't put a 9 or 40 slide on a 45 frame and have it work.

The 9/40 slide is shorter than the 45 so double action stops working. If you cock the hammer, pulling the trigger will trip the sear (so SA only)
The hammer also no longer reaches the firing pin.
Interestingly enough, the magazine will lock in the magwell if pushed forward. Space remains between it and the back wall of the magwell. It will feed 9mm rounds which amusingly fly out of the barrel when the 45 upper is installed.
Before you ask, no, a 9/40 barrel cannot be installed in a 45 upper - the locking lug is too short so it will not headspace properly.

Also intereting - the outer diameter of the 40 barrel is the same as that of the 45. No idea why they'd contour the same for 45 and 40 but not for the 9...

Can you take a 45 upper and _make_ a 9 or 40 barrel for it? Hypothetically yes. Then make a ring for the boltface, fit a new extractor, get a spacer for the magwell... But cheaper to buy a whole separate gun.

To Denner: what I say applies to full size px4s only. Compacts would appear to be different. I have since obtained a DA/SA slide in .40 and it's the same as far as barrel fitment goes as a DA only slide.

Cheers!


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## TTT

denner said:


> Where did you get that information? As far as I've researched everything between the 40cal PX4 and 9mm Px4(full size and compact) is interchangeable except the magazine, barrel, and I'd recommend the 40 cal recoil spring. The barrels and locking blocks having the same dimensions except the inner dimensions of the barrels(not the outer dimensions), with the 9mm barrel being thicker and the .40 cal. barrel being thinner.
> 
> I believe you can obtain a 40cal vs 9mm extractor as well, but one extractor is described as working for both calibers as well as the locking blocks, etc....
> 
> I own a .40cal PX4 compact and a 9mm PX4 compact. I can assure you the barrels, slides, locking blocks, etc...... are perfectly interchangeable with the others slide and frame. Likewise the .40cal and 9mm PX4's have identical dimensions except for the inner barrel diameter....The slides are not machined out differently and one is not heavier or lighter than the other.
> 
> http://www.brownells.com/schematics/Beretta-/PX4-sid879.aspx


Does the "feed ramp" between the 9mm and .40 S&W barrels appear different? Normally the answer would be obviously a "yes", but I thought I'd ask because of how high the cartridge sits in the magazine almost lined up with the barrel. I'm asking because I am curious how different a .357 SIG barrel would have to be since it fires a 9mm projectile. I have both 9mm and .357 SIG barrels for my P229 and I'd like to do the same for the PX4 Storm Compact.


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## ktfeich

Not _that_ much difference in the feed ramps... And the 357sig is bottlenecked so the feed ramp is less important...










I must ask though, who is going to make you a 357 barrel? EFK Firedragon used to make .40 and were very adamant the would not make any again - the px4 barrel is not that simple to reproduce...


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