I have a pair of 4046s that I'm in love with. I would like to get 357 Sig barrels as an option. I have 2 M&Ps (Full size and compact) that converted.
Does anyone make a decent 357 Sig barrel for a full size 3rd gen.
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I don't have Alzheimer's- My wife had me tested.

Unfortunately, I know of no manufacturer who produces a barrel, decent or otherwise, that will convert a S&W metal framed, center fire, semi-auto pistol to 357 Sig.

However, it can be done if you are a "do it yourself" sort of person.

John

Are you talking about a ream out, reline, and a re chamber?

_______________________
I don't have Alzheimer's- My wife had me tested.

The 4046 has a 4" barrel,how about acquiring a 3rd gen 4" 9mm barrel and reaming/rechambering to 357Sig ?

A past post for reference.
Smith 3913 Chambered in .357 Sig (pics)

I believe that my 40 cal slide is larger than a 9mm barrel. I will check one of my 5906 barrel and slide.
If it is the same, it would simplify.
_______________________
I don't have Alzheimer's- My wife had me tested.

Nothing quite that drastic.

If either of your 4046s are TSW models, a 59XXTSW barrel can be rechambered (with a finish reamer) to 357Sig.

If your 4046s are standard models, you can still run a rechambered 59XXTSW barrel but you will need to increase the angle of the barrel unlocking lugs beneath the barrel's chamber 2 degrees (S&W changed the dimension on the TSW models to delay unlocking).

To run a rechambered 59XX standard barrel on your 4046 frame, you will need to narrow the feed ramp on the 9mm barrel and replace the barrel bushing in the slide with the 59XX barrel bushing (the 40XX barrel bushing has a larger I.D.).

Another choice is to use a 5943/6 slide assembly and barrel (with the feed ramp area narrowed for the 4046 frame and the chamber reamed, of course).

And don't forget a heavier recoil spring. (I used a Wolff 22 lb. spring.)

John

None of my 3rd gens are TSWs.
I've considered using a 5906 standard barrel but, I can't locate a 5906 (Or a 5904) bushing anywhere.
The 5906 barrel doesn't look like it has enough meat on it for a safe ream out.

_______________________
I don't have Alzheimer's- My wife had me tested.

Would your risk your health and well-being doing this for a round that isn't even that pleasant to shoot.

You could still use the 59XXTSW barrel in your standard 4046 but you would need to increase the angle of the locking lugs 2 degrees (a tedious job).

The bushing would probably need to be sourced from a salvage slide.
S&W doesn't sell the bushing separately.
They classify it as "factory installed only".

Actually, the exterior chamber dimensions are the same for the 40XX barrels and the 59XX barrels.

The 40XX barrels have the thinner chamber walls so reaming a 9mm barrel to 357Sig would produce a chamber with the same wall thickness as a 40XX barrel.

This brings up an important point.
A barrel which was manufactured to be safe firing 35,000 psi nominally rated cartridges (9mm; 40s&w) is now asked to fire a 40,000 psi cartridge.

This is definitely the realm of the experimental and should be approached with caution.

There may be a very good reason no one offers a 357Sig barrel.

John

This alone tends to make me step back.
But think:
What about all of the 40S&W to 10mm conversions discussed on this forum?
_______________________
I don't have Alzheimer's- My wife had me tested

A totally different situation !
The CS40 is built on/from the CS45 platform so it has a larger diameter chamber area to start with.
The 4013,4014,4053,4054 are built on/from the 45 platform and there again have a larger diameter chamber area to start with.
ALL OTHER 40s' were built from the 9mm platform and DON'T have the larger diameter chamber area.

Reference pics added

Attached Images

	SampW4013vs4013TSWbarrels-01a_zpsb7811eaf wT S.jpg (266.4 KB, 24 views)
	SampW4013vs4013TSWbarrels-03a_zpsbd75bac4 wT S.jpg (104.7 KB, 24 views)
	DSC_4796 CC&A&C wTs A S.jpg (234.5 KB, 27 views)

The pictures posted by oldman10mm graphically illustrate the difference in chamber size and construction between the two frame sizes.

On top of that, the 10mm cartridge is nominally rated at 38,000 psi as compared to the 357Sig at 40,000.

I have no concern with the large frame barrel chamber being strong enough to contain 38,000 psi.

My concern is that the vast majority of these conversions are made on aluminum framed pistols.

Back in the day, even S&W admitted that the aluminum framed pistols gave up some measure of durability in exchange for weight reduction.

My own experience with the 357Sig cartridge persuaded me that alloy framed pistols were subject to excessive frame battering and therefore I only use the 357Sig barrels in steel framed pistols.

John

I did a quick check both of my M&Ps' chamber walls. I have 40s&w AND 357 Sig barrels for both. All four chambers miked at .085 (2 each, 40s&w, 357 Sig on an M&P and 40s&w AND 357 Sig on an M&Pc) at their skinniest points.
Since there are 357 Sig chambered M&Ps out there and no known (To me) M&P chambered blow ups on .085 chambered walls, It doesn't appear that a 357 Sig chambered 5906 with a nominal .090 wall thickness is anything to worry about.

Both of my 4046s are stainless steel anchors. Their frames don't worry me.
MY 410s, however, will forever stay a 40S&W.
_______________________
I don't have Alzheimer's- My wife had me tested

I don't have an M&P so thanks for the measurements!

The versatility of these pistols encouraged me to try.

I converted new barrels so the "bark and bite" of the first few rounds seemed a little hot.
I should try it with a worn in barrel, but it's a lot of cutting the entire length of the chamber.
It's not like lengthening a 40s&w chamber to 10mm.
That's only around 1/8" of cutting.

Good luck and keep me posted on the progress!

John

It appears that my problem is logistics. I have no prospects for acquiring 5906 barrels. I believe that I will have to fabricate barrel bushings, but I have no access to an engine lathe.
It appears that this project is back burnered for now.

_______________________
I don't have Alzheimer's- My wife had me tested