.357 Maximum Chambering

[GBertolet]

I have a Ruger #3 in .357 magnum. It was rebarreled with a 24", .358, Douglas 1-14 barrel, from the original .22 Hornet barrel. I just used it as a fun plinker. I live in PA, the Special Regulations area. Shotgun slugs & muzzleloaders only for deer. The law was just changed. Now any straightwall cartridge regardless of length is now legal. Hence, upgrading to the .357 Maximum. The case is 5/16" longer than the magnum. I have been gifted a .357 Maximum reamer.

My question is, being only lengthening the chamber 5/16", can I just do this manually with a t handle, instead of removing the barrel, and doing the chamber cutting on a lathe? Other than removing the stock, I think this can be done on the complete rifle. Sure beats making witness marks, and having to remove the barrel. I will do it if I have to, but if there is an easier way, with still getting good results, I want to do that. I still will be able to shoot .357 magnums out of it. All I now use, anyway are cast bullets. I have a Lyman 358315, 205 gr GC bullet mold, I would like to try, after the conversion. I have been told that 35 Remington ballistics can be duplicated.

[Texas by God]

I would do a simple rechambering like that by hand like you describe; going slowly and carefully.


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[Der Gebirgsjager]

Were it 20 years ago and I still in the gunsmithing business, if you brought the chambering job into me to perform I would do exactly as you propose. You need a T-handle, finish chambering reamer, cutting oil, some kerosene, and Go and No-Go gauges. Swab the chamber with plenty of oil and coat the reamer with oil. When you push the reamer into the chamber be sure to turn the reamer only in a clockwise direction, assuming that it is a right hand twist reamer (left hand twist is rare). Even when you withdraw the reamer turn it clockwise and pull to the rear. Why? Turning the reamer clockwise traps the metal chips in the flutes. Turning to the left risks trapping them between the flutes and the chamber walls and scoring the chamber. Reamer is out, swab the chamber and clean the reamer with the kerosene. Dry the chamber with a cleaning patch, insert the No-Go gauge and gently try to close the breech bolt. Don't force it. When you hit the proper depth it will close snugly and the Go gauge will fit. Don't try to do the job all in one step with 50 reamer turns. Withdraw the reamer, clean, dry, measure every 4 or 5 turns, fewer as the No-Go gauge gets close to fitting. Be patient, as if you remove too much metal you can't put it back. 5/16" is a small amount and shouldn't take long to complete It is unlikely that such a small amount will result in a rough chamber, but if it does you can smooth it with an appropriate sized wooden dowel that has a slot cut in the end and a small piece of 400 grit W&D sandpaper dipped in kerosene and run in an electric drill for 10 seconds.

DG

[Mk42gunner]

Without looking it up, I am going to guess the .357 Magnum and .357 Maximum share the same headspace gauges. If so, be sure not to increase headspace when you lengthen the chamber.

Be very careful when the rim recess of the reamer gets close to touching the barrel and extractor.

Other than that, it seems very doable by hand.

Robert

[Plinkmeister]

der Gerbirgsjager,

Excellent write up. Thank you.

[405grain]

The chamber can be changed from 357 magnum to maximum by hand, and if done carefully it should be quite good. I use an extended reamer holder so that it won't interfere with the action. Use plenty of cutting oil. make small gentle cuts - don't try to hog out a lot of metal too quickly. Avoid chatter; chatter is a chamber's worst enemy. Make several cuts instead of trying to cut it all at once. Clean off the reamer between cuts to keep the flutes from clogging. Clean out the chamber between cuts to prevent a cutting edge on the reamer from riding up on a chip and trying to compress it inside the chamber. It is important to have the chamber clean when using a GO gauge because if the gauge hangs up on a chip it will give you a false reading. I blow out the chamber with an air gun before testing the headspace to make extra sure that there are no chips hiding inside. Lastly, once the chambering is complete I run several patches through the barrel to remove all of the cutting oil.

[GBertolet]

I don't have go-no go gauges, but I do have some .357 maximum brass. I think I could ream until a case chambers.

[Der Gebirgsjager]

Perhaps so, if the case is a new one not stretched by previous shooting. Rimmed cartridges technically headspace on the thickness of the rim, but that recess in the chamber mouth should already be cut if you're using a .357 Mag. barrel, so the critical measurement is the length. You'll need to cut a throat area as well to accommodate the bullet, and that is usually part of the reamer design. So which reamer is important and different reamer manufacturers make them to different specifications. Drawings are often available and the makers are usually willing to discuss their products on the telephone.

DG

[GBertolet]

The brass is new Starline, and I found I have a Manson 35 caliber throater reamer, in case I need one.

[rockrat]

I did my #1 357mag by hand, just as describe above. Go slow. 357max. is quite an improvement

[GBertolet]

Well, I had a minor setback. There was not enough clearance on the back of the falling block's loading chute, to attach the T handle, so I had to remove the barrel. No big deal, although I had to disturb my Hicks accurizer setting in the process. I will have to discover the sweet spot again. Anyhow I did the job in my lathe, with no issues.

I ordered a lb of AA1680, as that I have been told is the go to powder for the Maximum, with a 24" barrel, also 1K of Rem 7 1/2 primers, as they are the recommended primer to use also. Mid South had a special on these, with free hazmat. In the interim, I tried loading a few rounds with 296 powder, and my 358315, 210 gr bullet. I went up to 22.5 gr, with no issues on pressure. No chrono info on this loading. I suspect I could go a lot more, as the #3 Ruger is a strong action. This may not even be the best bullet choice for the Maximum. Mike Bellm likes the 180 gr jacketed bullets for the Maximum.

Anyhow the saga continues.

[contender1]

Kudos on getting the chambering done.

A well known IMHSA champion,, David Bradshaw helped design, test & published the G&A article on the Ruger .357 Blackhawk. This man knows the guns & calibers.
Well not too many years ago,, David as well as a gentleman named Lee Martin teamed up, to design a cast bullet for the Maxi.
The "Bradshaw/Martin" bullet, is a 194 grn, GCed bullet.
David & Lee tested it extensively before telling folks about it. Now,, their work was done in a revolver,, not a rifle. But they found that IMR 4227 was the best powder,, along with the Rem 7-1/2 primers. And they deep-seat the bullet just over the front driving band.
I have 2 of the molds,, and have cast several thousand of them. I've used them for hunting & they deliver. Dick Thompson,, (aka sixshot) took the first deer with one of those bullets,, a mulie. I took the second deer,, a whitetail.
They are accurate & have caused me to mothball a few other heavy for caliber molds.

To read a lot more on this,, you can go to another forum,, the singleactions forum run by Lee Martin. Search the Bradshaw/Martin and you will find a LOT of info. (I THINK the web address is www.singleactionsproboards.com ) I have it bookmarked so I can't exactly remember.

[GBertolet]

I got to chrono the 22.5 gr 296, with the 210 gr bullets (actually 214 gr w/gas check) 2054 fps. Not too bad, groups in 2" range @ 100 yards. I think I should do better. Maybe the 1680 powder, or 4227, will do be the answer.

[GBertolet]

Still not satisfied with the 210 gr Lyman cast, and the 200 gr Lee I just purchased. Out of desperation I tried the bullet I use in my 35 Whelen Imp, a 240 gr SAECO. This bullet shoots great, with both AA1680 and 296 powders. 1850 to 1900 fps. 1 to 1.5 inches at 100 yards. All of these bullets are powder coated.

I tried shooting this bullet into some wet phone books, soaked overnight in a tub of water. 14 inches thick. The two shots fired, blew right through it, with large exit holes. A large trench cut into the berm, with no recovery of the bullets.