Taurus 357 - getting ready for cast

[wquiles]

When I was teaching NRA basic pistol almost 20 years ago, I purchased a Taurus 357 revolver brand new (7-shot) which of course I used with dummy rounds for class, and 38 special loads for range:




Since I built the 358Win Mauser rifle and have 358 cast bullets, I figured it would be cool to try some of these bullets in the revolver. I recently ran into this thread where the forcing cone was shown before and after:
link

So I decided to take some photos of mine:





WOW.

So yes, I will be needing to "clean that up" before I start with cash bullets

The cyl throats are also too small, so I got from ebay a brand new .359" reamer and a .3594" reamer for about $10-15 each (not bad!), so I will be doing that as well.

Tips/advice on both (forcing cone) and reaming the cylinder?

Will

 

[RBHarter]

I had one of the 66s . It would shoot up through +P38s step over the line into 357 poof no more groups .
The best bullet I ever shot in it was a 85 gr Gold Dot for a 380 .
That being before my enlightenment I didn't check throats or groove dia . I suspect that what I had was 9mm dimensions all those years ago .

 

[Ian]

Brad turned and threaded a brass lap for the forcing cone and bushings for the bore to do one of his, that's the approach I'd take. I've polished a few out with a lead lap and cleaning rod.

Here's how I ream cylinder throats, maybe you can think of a better way. Measure the cylinder throat length approximately and bush the chucking reamer with even layers of masking tape (don't overlap the start and end or half lap the layers) until it is a very snug fit in the chambers and enough cutting surface protrudes to cut the throat all the way through. Put a tee-handle on the reamer, oil it up, and crank it through. Clean up the surface with 400-grit oiled emery paper and a split rod. Important tip: Take an India stone and break the sharp corner at the start of the flutes; if you don't, slight wiggles while reaming will cause it to cut deep spiral scratches in the throats. Like I said, maybe you can come up with a better way, like with a 4-jaw chuck, brass shims, and a Last Word indicator. I'd also only use the .3574" reamer and polish to .358" or so. Throat size = bullet size and there's no need to go bigger than the barrel's groove dimension.

 

[Cherokee]

I notice you have a ported barrel - in my experience it will collet lead. I had one in 6" a few yeas ago, one session of 50 rounds had the ports half filled and the target looked like a shotgun pattern. It shot jacketed bullets beautifully, but cast - no. The gun went down the road. Hope yours does better.

 

[Brad]

I would do what Ian mentioned. Ream a bit undersized then polish to final size.

Forcing cone is simple. Make a brass lap of the correct angle. Thread front, small end, for a steel rod. Make a conical bushing for muzzle that is a snug fit to rod. This keeps muzzle end of rod centered. Make a small, straight brass bushing that is a snug slip fit in bore at breech. This keeps the breech end of rod centered. Charge the lap with 240 grit silicon carbide in grease and spin with drill while pulling lap firmly into forcing cone. Stop and clean often. Once smoothed up charge lap with a finer grit and repeat.

It takes merely minutes to lap the forcing cone smooth and concentric.

Might need to do some searching to find the factory angle for the cone.

 

[wquiles]

Thank you guys for the detailed advice. I will proceed as you guys suggested, and as always, I will include work-in-progress pictures

 

[Ian]

Before you start working on the forcing cone, machine a plug that just slips into the muzzle and slide it through the barrel to check for thread choke at the frame. If there is significant thread choke, I would suggest Pisolero's fix of removing the barrel and checking again to make sure it relaxes and if so, machine the shoulder back slightly until it will index back where it was originally but only with hand pressure and intall it again with threadlocker.

 

[Brad]

Pin gauges work well for that as well. Just don’t get one stuck!
I like to make sure the gauge is shorter than the cylinder window so it can easily clear the forcing cone.

 

[freebullet]

Moms m85 does lead the ports a scootch but not bad. Seems like maybe just antimony wash that comes off easily.

 

[wquiles]

Before you start working on the forcing cone, machine a plug that just slips into the muzzle and slide it through the barrel to check for thread choke at the frame. If there is significant thread choke, I would suggest Pisolero's fix of removing the barrel and checking again to make sure it relaxes and if so, machine the shoulder back slightly until it will index back where it was originally but only with hand pressure and intall it again with threadlocker.

Gotcha. I still have some pure lead, I will use a piece to check the bore OD and then also check for a choke point. In the past, I have done fire lapping to get rid of the choke point.

 

[wquiles]

Moms m85 does lead the ports a scootch but not bad. Seems like maybe just antimony wash that comes off easily.

I am planning on only shooting PC-coated cast bullets, so hoping it will be less of a problem.

 

[wquiles]

OK, got the bore checked out - just slightly over .358":






So the .359" reamer is about right:



All done - after this, I did a light polish:



I also worked on the forcing cone, but the 11" plug didn't match the factory angle. I will post pictures later today.

 

[Brad]

After a light polish a .3585-.359 bullet will be about perfect.

Looking good

 

[fiver]

I'd just shoot it after doing the throats.
probably shoot it with some lapping compound in lieu of bullet lube [shrug] but that's just me.

 

[wquiles]

Here is the work on the 11deg plug:




But it only touched/polished the very edge of the barrel - nowhere the area where the bullet would actually touch. So I remembered Ian talking about using an actual bullet, which is what I used:



That actually worked better, and got a "little" bit more clean-up where the bullet would start engaging the cone, but still not enough:

 

[wquiles]

After a light polish a .3585-.359 bullet will be about perfect.

Looking good

Thank you. I am going to try to .359" and see how it goes

I'd just shoot it after doing the throats.
probably shoot it with some lapping compound in lieu of bullet lube [shrug] but that's just me.

That is exactly my current path forward. I am going to look, but I am pretty sure I still have some left over lapping compound left.

Given the short 4" barrel, I am thinking that 1.0 gr Bullseye should be enough for lapping rounds, right?

 

[Brad]

Soft, throat sized bullets with 1 gr BE would work. You can even deep seat them to keep grit contained in case.
i like to fire at very short range on paper to know for certain that each bullet exited barrel.
Clean cylinder and bore every 6 shots. Plan on 24-36 rounds total.

 

[wquiles]

Soft, throat sized bullets with 1 gr BE would work. You can even deep seat them to keep grit contained in case.
i like to fire at very short range on paper to know for certain that each bullet exited barrel.
Clean cylinder and bore every 6 shots. Plan on 24-36 rounds total.

Thank you for the guidance - much appreciated

 

[wquiles]

Finally got to the range today - fired 28 rounds (4x cylinder fulls):



Shot at just a few yards, shot left to right, to make sure I can see each bullet hole:



I hope to clean the revolver tomorrow or Tuesday, and take some close-up shots to see if things are improved or not.

Will

 

[wquiles]

OK, here are some before and after pictures. First from one side:

before:


after:





and the other side:
before:


after:





The angle of the light and focus on the phone's camera make it hard to have the same exact photo for the before and after, but I think it has been improved after fire lapping. I need to shoot it some now, and see how it does

Will