357 tight(?) chamber

[donhuff]

RD, and anyone else too, did you see my post in the reloading section, 45-70 and IMR 4198? And the part where I tell about the size of the chamber in my 357. Nobody mentioned it so I wanted to talk about it some more to see what yall have to say on the subject.

" I know my 357/92 has a "tight" chamber. Not really tight, but more to what it ought to be I guess. I size 38 bullets to .359 cause my blackhawk measures .358, But depending on the thickness of the brass, some of theese loads will get half way into the chamber and then start to bind a little. You can force them on in without too much force but the hull will have rub spots on them. I thought about running a reamer into the chamber to open it up a little so i dont have to have two sizes of slugs. I poured a cast of the chamber, and the rear half was about .002 bigger than the forward half. The same bullets that are tight in the Rossi, have a lot of clearance in the Rugers cylinder."

It works and I guess I should be happy that I have a tight chamber since they are supposed to be more accurate. But this aint no target gun, and after spending a lot of time getting it all slicked up inside, so that the action is smooth. It aggravates me that ever so often I get a "fat" round that is stiff getting into the chamber. I rechecked the chamber cast yesterday, and yes the rear half of the chamber is .002 larger than the front half. A cartridge that measures .379+, will be tight. I tried using sandpaper on a stick for a little, to try and open it up some, but got scared of doing that as you can"t ever get that to turn out very true. I'm thinking a chucking reamer @ .381" will slide right in to the .381 part and then it would ream out the other half real easily and should stay pretty true with the back half guiding it.

What do yall think?

[44-40 Willy]

SAAMI specs on the chamber are .3809 to .3801 Here is the specs drawing for 357 Mag.

[donhuff]

8 ten thousands smaller from rear to front. So .381 would be really close to what they want. I have no idea as to how I would get that taper in there without a chamber reamer. I wonder if that matters that much.

[Ranch Dog]

Personally, I like the SAAMI cut of the Rossi and would not mess with it. The problem with using a .359" bullet is that you are .004" overbore going down the barrel. Both of my R92s chambered in 357 Mag slug the same: .355".

If you do the work, you should use a Tapered Throat Reamer so that you chamber remains concentric. You would also need to remove the barrel from the rifle to do the work. Finally, you might be able to rent the reamer but if not I suspect that it would run right at half the cost of the rifle. Much easier to segregate your ammo and size .357".

[donhuff]

Personally, I like the SAAMI cut of the Rossi and would not mess with it. The problem with using a .359" bullet is that you are .004" overbore going down the barrel. Both of my R92s chambered in 357 Mag slug the same: .355".

If you do the work, you should use a Tapered Throat Reamer so that you chamber remains concentric. You would also need to remove the barrel from the rifle to do the work. Finally, you might be able to rent the reamer but if not I suspect that it would run right at half the cost of the rifle. Much easier to segregate your ammo and size .357".

Well, if I had a "spec" chamber, I think I would be ok. As that would give me .0011" more clearance in the front and almost ,002 in the rear. And would give me plenty of room cause it just bearly rubs now. I don't want to mess with the throat. It is fine as is. Just make the chambe a little bigger. I can load a Lyman 358429 way out to 1.700+ and that's probably the heaviest bullet I plan to use.
I re-slugged the barrel yesterday to be sure. And I get .356 on one set of ridges, .3565 on the next and .3572 on the last set. So .359 aint too big, depending on where you measure.

[Ranch Dog]

RD, and anyone else too, did you see my post in the reloading section, 45-70 and IMR 4198? And the part where I tell about the size of the chamber in my 357. Nobody mentioned it so I wanted to talk about it some more to see what yall have to say on the subject.

Sorry about that, I read all the posts here but more on the "moderator" level, if the conversations seem normal, I move on many times depending on the volume of posts or my workload at home. It is always better to open a new topic with info that is along another topic.

I'm thinking a chucking reamer @ .381" will slide right in to the .381 part and then it would ream out the other half real easily and should stay pretty true with the back half guiding it.

8 ten thousands smaller from rear to front. So .381 would be really close to what they want. I have no idea as to how I would get that taper in there without a chamber reamer. I wonder if that matters that much.

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Okay, please disregard my previous reply. The reamer needs to be a floating piloted reamer or there is a huge chance of a nonconcentric chamber being cut. What I would consider, if in that the rear dimension is what needs to be increased is renting this reamer: 357 Mag Floating Pilot Reamer



These reamers cut a SAAMI spec chamber and what it will do in the case of your rifle is leave the front dimension alone and cut the rear dimension to from .379" to .381". These reamers are a hand tool and are very easy to use, you will find that the steel is much softer than expected and why it is never to work on it except with a precision tool. What would be important info now is the bore dimension of your chamber cast. This dimension would determine the pilot you need. Use .346" for the base and you will notice on the rental page that you select how pilots in .001" increments to fit your application. If you are a little uneasy with the measurement, error an additional .001" based on what you are measuring as that will include the additional pilot. If you need some wierd size pilot, go to the "Tools" menu under "Firearms" and rent the specific pilot for $3 rather than paying for a series of pilots. "1 undersided pilot" is the norm. In other words, a .345" pilot is going to slide into a .346" bore.

You will also need a T-Handle. With the guts of the receiver out, this reamer and handle should be able to move right up the middle. I would do a 3-day rental and but have the time and rifle ready as you will probably receiver the tools the day after you order them. This is going to take mere minutes to do and it is really not going to remove much metal. Oil it up with gun oil, cut it down to the indention for the rim and STOP. That is it.

This is how I would do it.

[donhuff]

Now your making sense.

I thought about grinding the nose of a chucking reamer and making a guide for it, but i would have a lot of time involved by the time I got finished. And like you said, it won't take 5 minutes to do the cutting.

Seems like a lot to go through for just .001" of metal.

Thanks for the links.

[ironhead7544]

You could try modifying a Lee Factory Crimp Die. These dies are made to size the cartridge to fit standard chambers. Since you are using oversized bullets for the revolver, you could modify the LFC die to reduce the cartridge by .001. Might not effect the revolver. Will be worth a try.

[donhuff]

You could try modifying a Lee Factory Crimp Die. These dies are made to size the cartridge to fit standard chambers. Since you are using oversized bullets for the revolver, you could modify the LFC die to reduce the cartridge by .001. Might not effect the revolver. Will be worth a try.

I did something similar to what your saying today. I took an old die annealed it then drilled it out and reamed it to .375, then lapped it to .3785. By the time I got finished polishing it out, it was right on .379. I then ran a few of those oversized cartridges in it and then they fell into the chamber just like the ones that are normal size. I was a little worried that it might be swaging the bullet down too much and would lose the grip of the case on the bullet. But it did not seem to affect it any as the few that I pulled had plenty of tension on them.