S&W .40 cal to 357 Sig

[floydster]

Has anyone necked down S&W .40 cal. to 357 Sig. I don't see why it can't be done, reason I ask is, I have a ton of the .40 cal. and the 357 Sig really intriques me.
Thanks for input, Floydster

 

[FN5.7shooter]

IIRC the case turns out a little short in the neck and one needs all the neck tension you can get to hold off setback. Also the max pressure seems like 40K psi on the 357 and 35K on the 40 but I could be wrong. Sure you could do it but it may not lead to the best 357 Sig experience.

 

[floydster]

FN5, thanks for the reply, I would basically use the necked down cases for light target loads, I shoot a lot of lead, and plated bullets.
Floydster

 

[ReloaderFred]

As noted, the length of the neck would be short, and the two cases are designed to withstand different pressure levels. There is plenty of 357 Sig brass available, and there's really no reason to neck down .40 S&W brass.

Hope this helps.

Fred

 

[FN5.7shooter]

I am using plated bullets from Berrys 124gr hollow points and flat points. Most common 9mm bullets don't have a straight bearing surface that is long enough to provide good neck tension. Berrys are the longest bearing surface I have found and reasonable priced. Keep velocity down below 1300fps and you should be good with the plated.
I just would not do the .40S&W case resize thing. Once fired cases are plentiful and reasonable.

 

[floydster]

Thanks guys, I guess I will hold off on the .40 cal re-sizing, heck I may get a .40 next.
Thanks for all the input.

 

[Z-Michigan]

As others said, the resulting case will be too short. To make this really important, 357 SIG headspaces on the case mouth, like most handgun rounds but unlike the vast majority of cases with shoulders (which usually headspace somewhere on the shoulder). So your headspace would be off, and when you add that to being 5k PSI over the .40 spec, I don't want to be at the range near you when you try shooting it.

 

[AgentAdam]

This is a nice read on sizing down .40 to .357sig.

part 1
http://www.realguns.com/Commentary/comar65.htm
part 2
http://www.realguns.com/Commentary/comar66.htm

 

[floydster]

adam,
Thanks for the link on the 357, an awesome write up. So, we now know it headspaces on the shoulder and not the mouth.
I think all the hipe on loading for the 357 Sig is mostly boloney.

Floydster

 

[AgentAdam]

True. Here is more on head spacing.
http://www.realguns.com/archives/001.htm

Using Lee Factory Crimp Die.
http://www.realguns.com/archives/112.htm

Even though its not a problem, im sure the cases will lengthen after a couple of firings. I wouldn't load them past 1,350 instead of the usual 1,450 due to the lower pressure ratting of the .40s&w. Should make for some good range fodder and would actually make something use full of of those bastard .40 shells all ways laying around in the way of all the good 9mm and .357 sig/mag. As far as the pressure rating goes most commercial full power .357sig loads aren't even taking full advantage of its ratings anyways.

 

[Sport45]

Sounds like it's time to buy a .40S&W barrel for your .357sig gun. That way you can put that brass to use without so much trouble.