sp101 cylinder swap

[bent406]

Longtime lurker, have a sp101 in .38 special, I came across a .357 cylinder from a sp101 and i was wondering if i could swap out cylinders ? The .357 cylinder is about a 1/16 of an inch longer than the .38, I have access to a surfacing mill to get the length correct but was wondering if I would have any other issues with swap ?
Number one being safety number two being any other fitting issues ?
Thanks

 

[Jimbo357mag]

I'm no expert but I know there are a lot of issues with fitting a cylinder. Would it not be easier to have the 38special cylinder bored to 357mag? Of course you would still have to watch the OAL of your rounds.

 

[6gun]

You take 1/16" of the cylinder your ammo may stick proud of the cylinder or close to it.

 

[Thel]

The two cylinders should be of the same length and only differ as to chambering. As the .357 is longer this suggests the the SP101 is of early origin. On those when Ruger started .357 production in them they could only handle 125 gr .357 loads as heavier loads would protrude and tie up the gun. Eventually, Ruger opened the frame window for the cylinder in the frame i.e. modified the frame to take the longer cylinder. When fitting a cylinder one must set headspace at the rear, the barrel/cylinder gap at the front and maybe adjust timing (hand to cylinder ratchet fit). It might also be necessary to set the barrel back a bit to adjust the barrel/cylinder gap. All in all it is far easier and cheaper to just have the existing cylinder reamed to take .357 and live with 110 and 125 gr bullets in it.

 

[bent406]

Thanks fellas, will that .38 cylinder be strong enough for factory .357 round ?
Also when you ream the cylinder do you ream it all the way through the cylinder ?
Thanks

 

[Mobuck]

I'm just wondering if you really considered how much(or how little) you'll gain by going to 357. A 357 short barrel is very inefficient, LOUD, and hard to control. The excellent 38 ammo available now cuts the advantage of the short barrel 357 considerably.

 

[Carry_Up]

i was wondering if i could swap out cylinders ?

Short answer, no u cannot.

The .357 cylinder is about a 1/16 of an inch longer than the .38, I have access to a surfacing mill to get the length correct

The .357 chamber is longer than the .38 spl chamber. If you shorten the .357 cylinder, it won't be suitable for .357's any more. So, what's the point? A .38 spl frame is not designed to handle .357. Hello.

was wondering if I would have any other issues with swap

Yes, you will. Although a few people may have been lucky with cylinder swaps, cylinders are fitted to a specific frame and internal parts are fitted to a specific cylinder. It is not the same thing as trying out a new magazine.

-cu

 

[6gun]

What you got to loose? grind it down and put it on see how it works, you won't know till you try it, personally I would leave it as is and trade it off for a 357, this is why I always tell people to never buy a 38spl. most of them always wish it was a 357 and want to turn it into one, just buy a 357 to start with.

 

[Thel]

"Also when you ream the cylinder do you ream it all the way through the cylinder"

No, when it is reamed the portion that contains the cartridge case (brass part) is lengthened for the longer case compared to a .38. The case has an outside diameter greater than the bullet. This will reduce the length of the throat in the cylinder (portion in front of the case to front of cylinder that the bullet exits) but not eliminate it. As to strength don't know. Back before Ruger made .357 SP101's Rick Devoid (a factory trained gunsmith) in New Hampshire was converting them to .357. See:

http://www.tarnhelm.com/services/services.html

and he rechambers to .357. As noted above because of the short cylinder length only light .38/.357 bullets can be used: 110 and 125 gr. as the heavier ones would protrude from the front of the cylinder and not allow the cylinder to rotate. Also, if not firmly crimped the bullet could jump the crimp and move forward and protrude.

 

[Thel]

and he rechambers to .357.

 

[bent406]

Thanks again for the help.

 

[Jimbo357mag]

Thanks fellas, will that .38 cylinder be strong enough for factory .357 round ?
Also when you ream the cylinder do you ream it all the way through the cylinder ?
Thanks

Chamber reamers are fairly cheap and any gunsmith worth his salt ought to have one in 357mag. No the cylinder is not bored all the way through as there is a slight lip in the chamber because the case is wider (.380") than the bullet (.358").
http://www.brownells.com/gunsmith-tools-supplies/barrel-blanks-tools/reamers/centerfire-reamers/pistol-chambering-reamers-prod17655.aspx

 

[GP100man]

The early sp101 frames were shorter, the frames were "stretched for 357 magnum. They now chamber 38spec. on the longer frames, just longer throats.

If you were to fit the 357 cyl to your 38spec frame the throats would be very short & it`d be hard to find a short enuff bullet that it would`nt stik out the face of the cyl unless ya handloaded 357 wadcutters.

I have a 3"sp101 with the short frame & I don`t feel under gunned at all !

If ya want more power or a range gun may I suggest a 4.2" GP100 ??
The compact grips are very close to the sp101 grip

 

[Bustedglockv2]

Fire some .38spl +p+ and get more power out of it! or trade to for a ?357