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11-degree forcing cones?


Fishbreath
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I've had some trouble with leading again this summer—maybe an artifact of working up my load in cool weather with temperature-sensitive Clay Dot? I'm hoping to experiment with some other powders in the offseason, but that will depend very much on availability, so I'm looking at alternate options too, like taking the endshake shim out so that it's a bit more forgiving of grit on the recoil shield.

 

I'm also wondering if maybe I should try an 11° forcing cone. Does that dramatically reduce leading over the stock Ruger 5° forcing cone? I hear it can make jacketed bullets work less well, which I don't care much about, but in what way do they get worse?

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I use the 11 degree forcing cone because that's the one I like the looks of. There is no "magic angle" for forcing cone or muzzle crown. As long as they are concentric to the bore, smooth, and the right size, just about any will work. I can't tell any difference in accuracy between a 5, 11, or 18 degree fc. I get 3/8" groups at 25 yards and a little over an inch at 50 yards from a 6" 686 in a Ransom Rest. The barrel on that gun has an 11 degree fc. The bullets are 125 gr. JHP. I don't think I'm losing much in the accuracy dept.

 

The main barrel related things that affect accuracy and leading in a revo are: forcing cone, chamber to barrel alignment, barrel constriction just ahead of forcing cone, and muzzle crown. If all those are in spec. and you're still getting leading, it's ammo related. Ammo could be too soft lead (swaged), wrong bullet lube, too hot powder charge, etc.

Edited by Toolguy
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Check your alignment of cyl to bore and make sure you are not damaging the coating while loading. The 11 deg cone gives a gentler alignment for cast and can help with a slight cylinder to bbl misalignment or so I’ve been told. Does the leading start right at the cone or is it farther down the bore. Are you getting ALL the leading out when you clean? A small amount left over will start the leading process all over again. 

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I have no lead in any of my barrels since I moved to coated bullets. Unless something is damaging the coating, the lead does not touch the barrel. Pull a few loaded bullets. Are you cutting thru the coating with the crimp?

 

I do get some plastic buildup in the barrel. That stinky shotgun solvent knocks it right out though, it's designed to remove plastic wad fouling.

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As is my wont, I've been unclear describing the problem. I'm not getting leading in the bore, as far as I can tell—I'm getting lead buildup on the frame around the forcing cone, a little stalagmite on the bottom of the top strap, and a little buildup on the the front face of the cylinder. No accuracy trouble, though; it'll drive tacks even shooting .38 Short Colt.

 

I'm not damaging the coating—I'm crimping to a straight wall, and pulled bullets don't show any cutting or compression.

 

I spent a few hours getting all the buildup out once or twice, but it just comes back.

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3 hours ago, Fishbreath said:

I spent a few hours getting all the buildup out once or twice, but it just comes back.

 

Same thing with every revolver I own. I think it's the nature of the beast.

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Sounds like you need a little bit bigger forcing cone and possibly tighter cylinder gap. That lead has to come from somewhere, and the bullet is the only lead part of the equation.

Edited by Toolguy
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I use 11 degree on the forcing cones on any revolver I touch.

 

I did find a very slight accuracy increase at 25 yards with the Smiths but I did a friends 2 GP100's that were leading severely.

 

The cylinder alignments were good, but I cut the forcing cones anyway and the leading stopped completely, but I don't know if there was any accuracy concerns afterwards.

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35 minutes ago, Toolguy said:

possibly tighter cylinder gap

 

That's a 'back to the factory' kind of job, yes?

 

8 minutes ago, RePete said:

I did find a very slight accuracy increase at 25 yards with the Smiths but I did a friends 2 GP100's that were leading severely.

 

The cylinder alignments were good, but I cut the forcing cones anyway and the leading stopped completely, but I don't know if there was any accuracy concerns afterwards.

 

Well, that definitely suggests that I should see if 4D Rentals has forcing cone reamers on hand. Thanks—any scrap of experience with tuning Rugers is worth its weight in gold to me.

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In my 625 I've noticed that Clay Dot started fouling the cylinder, leading to rounds hanging up on reloads.  It was happening with Berry Plated & several coated bullets.  Haven't noticed it in my 38 short colts though?  

So I started using Ramshot Competition in my 45 acp loads and the problem seems to have disappeared.  Hope it doesn't start being a problem in my SC, only have 16 pounds to use up?

On the 11 deg forcing cone I used it on my 625 and M29 and it did seem to help with flyers, but didn't notice any overall accuracy gain, outside of the flyers.    That lead buildup on the frame is natural, BUT you shouldn't have stalactites. 

Remember not all coated bullets are the same too.  Bayou, BBI, ACME, Precision I have extensive experience with and have no problems.  I have had others that were a serious problem.

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After it’s cleaned up check your gap with a feeler gauge to see what it is. Most of the time if it’s .006-.008 Ruger will say it’s within spec and won’t do anything unless they’ve changed their policy.  You may be getting some burning/melting at the base of the bullet and that’s where the crud’s coming from. Try shooting some into a phone book or barrel of water to recover it and check out the base and sides. You can learn allot by that.  Bevel based bullets are worse. Just might try a different powder first. 

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Posted (edited)
1 hour ago, Farmer said:

Bevel based bullets are worse.

 

I am using bevel bases. Maybe I'll get a sample pack of the Bang and Clang 160s and try some without.

 

I'd love to try some new powders, but nothing's been in stock lately.

Edited by Fishbreath
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1 hour ago, Fishbreath said:

 

I am using bevel bases. Maybe I'll get a sample pack of the Bang and Clang 160s and try some without.

 

I'd love to try some new powders, but nothing's been in stock lately.

Yeah that’s the real bitch about all of this crap. Do you have any other powders to try? What I’ve found on the BB bullets is with hotter powders or high psi loads they tend to not seal as good at the base allowing for some flame cutting of the bullet. See if you can capture some fired bullets, it just may be some of the coating that’s building up on your gun and not actual lead. 

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Posted (edited)
9 minutes ago, Farmer said:

Do you have any other powders to try? What I’ve found on the BB bullets is with hotter powders or high psi loads they tend to not seal as good at the base allowing for some flame cutting of the bullet. See if you can capture some fired bullets, it just may be some of the coating that’s building up on your gun and not actual lead. 

 

I have a little Clay Dot, a little Bullseye (which isn't substantially cooler, but I guess worth a try), and a little 3N38 (which probably isn't going to work for this application).

 

I'll see what I can do about capturing a fired one.

Edited by Fishbreath
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One other thing I forgot to tell you is to take a new bullet and see how it fits the mouth’s of the cylinder. With a clean cylinder they should just slide through with light finger psi. If they are scraping the coating that could be some of your problem. I had a S&W M10 that was undersized and would size down SWC lead bullets badly and lead the bore  until I opened them up. 

Edited by Farmer
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8 hours ago, Farmer said:

One other thing I forgot to tell you is to take a new bullet and see how it fits the mouth’s of the cylinder. With a clean cylinder they should just slide through with light finger psi. If they are scraping the coating that could be some of your problem. I had a S&W M10 that was undersized and would size down SWC lead bullets badly and lead the bore  until I opened them up. 

 

This was a potential issue, but I reamed the chamber throats for lead bullets, and the bullets only take light finger pressure now.

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I would spec the cyl chambers throat's exit diameter for chamber to chamber consistency and if not hone to the largest..  I would check their alignment with barrel bore and firing pin bushing hole centerlines at lockup.

 

Checking headspace and cyl to cone gap from both sides for all chambers to ensure things are running true to under a thou is something I would do. 

 

How much movement is there on cyl rotation once cyl is lock for each chamber.   If the cyl gap is not huge and it has some cyl rotation play once locked I like the 11° for more than just looks.   I do like the look of it a lot.  Gives it  more finished higher end look.  I think you loose a bit of vel but it gives a slightly more gentle angle for bullet alignment to bore centerline as it traverses the cyl to barrel especially if things need to slightly align via  bullet.

 

I also prefer to throat all my barrels similar to precision rifle chamber throat specs to fully support the bullet before gradually engaging the lands with a 1° leade.  But that's a whole other level of work and ordering a one off reamer.  Way nicer if your working on a 2 piece shroud and sleeve setup.  If S&W offered them in more N and L frames it's all I would own new in those frames.

 

 

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4 hours ago, tim_w said:

I would spec the cyl chambers throat's exit diameter for chamber to chamber consistency and if not hone to the largest..  I would check their alignment with barrel bore and firing pin bushing hole centerlines at lockup.

 

They're already reamed to .358". I do need to get a range rod to check timing really accurately, although it looks correct with the light-behind-the-cylinder test. Checking for trueness in the cylinder through its rotation seems like a good idea—I'll give that a go, too.

 

I went ahead and ordered an 11-degree reamer and gauge set from 4D, as well as some 160gr bullets from Bang and Clang. Same coating as the SNS bullets I'm using now, but no beveled base or lube groove. Hopefully some of those changes, along with maybe some exploration of different powders, helps. I guess I need another .38 Short Colt die set now—my turret press is perfect for this kind of R&D, and I don't want to have to pull the dies off of the 750.

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Remember, if it ain't broke...

 

My 627 holds the A zone on a turtle at 50. This is with a factory forcing cone, beat up cylinder notches, an ugly crown and a clocked barrel. It might do better if I fixed all these things, but my machine shop instructor once told me that "The more you F with something, the more likely you are to F it up."

Edited by PatJones
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12 minutes ago, PatJones said:

Remember, if it ain't broke...

 

 

....find any excuse to wrench on it so then you really have something to fix?   I am very good at ensure new work to do 9n my guns lol   But I do enjoy it and learn a lot reinventing numerous wheels.

 

 

Look forward to see the effects.  I would just try Thebes bullets first and see that effect then decide on the cone.  As long as you take your time and polish it the only undesirable but minor change was a small drop in vel.   That's what's so nice about the models that use the barrel sleeve shroud setups.  It's so easy comparitively to dial in your cyl gap.  Also makes it much easier to work the cone and or crown.

 

Getting ready to pu a new model 19-9 Combat to create a new build for stock Rev IDPA.  It's nice with all the SS guns these days to have a good ol tough 4140 forged revolver and with a shroud and barrel sleeve tension setup to build.  Looking forward to seeing how it develops and performs.  Want to mod the barrel sleeve setup to make it more user friendly to adj more like my 327 PC JM or a DW.  8 also think I have a compatible dedicated 38 spl cyl so it's shorter and lighter.  No jump in the 357 cyl and a nice  short snug throats.  Anyways tweaks and parts I want to experiment with.

 

Interested to see if those new bullets improve your leading.  Keep  the thread updated.   Good kuck

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13 hours ago, PatJones said:

Remember, if it ain't broke...

 

It is broke enough to be causing me substantial trouble at matches, at least, and has been since I started loading coated lead, with occasional reprieves (not-so-coincidentally coinciding with my best match performances). Drag marks on the front of the cylinder after 50-100 rounds, and notchy double action trigger pulls thereafter, seem to me to need fixing. (I thought it might have been a broken firing pin spring again, but on checking, it turns out that it wasn't.)

 

I do find myself undoing a lot of the other things I've done, though—the stock hammer lives in the gun again now, along with the stock firing pin. I suspect the bobbed hammer needs the same fix in re: Ruger wall that I recently made to the stock hammer, but I can live with the 7.5-8lb pull if I can get the jamming figured out. The extended firing pin is a project for another time, since it needs to be cut down to flush. It comes with a shim kit for non-destructive fitting, but that exposes the protruding bushing to battering by the hammer/transfer bar, and I think that was letting the bushing work loose much more easily than it should have.

 

12 hours ago, tim_w said:

...find any excuse to wrench on it so then you really have something to fix?

 

This is what my 3D printed Open Glock is supposed to be for (on the theory that it's never going to work all that well and I don't care about the division very much, and therefore the gun will always be a valid target for tinkering). I'm hoping to get the revolver to 'it just works' territory ASAP, so I can get on with the business of improving without having to worry about functioning.

 

12 hours ago, tim_w said:

Keep  the thread updated.

 

I went ahead and measured headspace and B/C gap. Both measurements are at 0.009"-0.010" all the way around, which is right in the middle of the Ruger factory spec for headspace, and not quite in the optimal range for B/C gap but below what Ruger calls the maximum acceptable. Now that I'm pretty nearly done with matches for the year, a trip back to Ruger stings a lot less than it would've during the summer, so depending on my results from load changes and perhaps forcing cone cutting (also recommended by Ruger DA expert Iowegan at rugerforum.net, for lead bullets), it may be going on the field trip.

Edited by Fishbreath
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