forcing cone

[porkchop]

I have a S&W 686 which I think the forcing cone was not cut deep enough by the gun smith.I had him cut to 11 degree and make the throats in cylinder all .358" to shoot lead wad cutters for Bullseye shooting.
How deep should the cone be cut ? I'm just using the beam part of my dial caliper to check. The measurements are: barrel length from muzzle to back is 4.223"
length from muzzle to groove is 4.003"
length from muzzle to land is 3.973"
I pushed .358" DEWC and .357" HBWC in with light finger pressure and they went in
.225" DEWC and .248" HBWC.
My main concern is the leading I'm getting, I normally use 38 special brass tried 357 mag brass, I get same results. Some flakes of lead inside of throats to the end of cylinder in first few rounds, then lead build up. Forcing cone leads up some then builds up at begining of lands and grooves big time after 30 shots and more. I load 2.7- 3.0 grs BE, seat them flush in the groove light crimp or heavy crimp, I've also tried both taper and roll crimps. The taper crimp does better.
I have'nt tried a range rod to check alignment because she don't spit lead out the sides, I have not checked throats to see if they are truely .358" after the work done.
Any help appreciated. Stan

[Preacher Jim]

did he polish the cone?

[porkchop]

Yes, it's pretty smooth with no machining marks .

[porkchop]

These should show the smoothness.

[Dan Cash]

Yoou don't say whether you are using commercial wad cutters or your own cast. I am pretty sure that the bullets you are using are too hard. If you are casting yourself, soften your alloy and use a beeswax based lube with vegetible oil. Your description does not sound like a serious problem but a bullet .001 larger might eliminate the lead build up.

[jrayborn]

It looks to me like it is maybe a bit shallow on the throat if it is indeed 11 degrees. Hard to say for sure without the gage (yes they make one) but in my experience, a little more would help.

[porkchop]

Dan, right now I'm using commercial, the .358"DEWC are said to be 12bhn and the .357"HBWC are swaged. I think you are right about bullet hardness, today I loaded the DEWC to 3.2gr BE and throat leading was less after 30 rounds. I tried 30 that were loaded to 3.5gr of BE but they were not that accurate and leading worsened in the cylinder throats and the first inch of barrel (probably another issue to address).
If I go to .359" and softer alloy could that worsen cone or barrel leading, I don't know the groove diameter of my barrel because it has 5 grooves and have not figured how to do it.

[.45Cole]

I am pretty sure that the bullets you are using are too hard. If you are casting yourself, soften your alloy ... Your description does not sound like a serious problem but a bullet .001 larger might eliminate the lead build up.

My thoughts exactly! At 12BHN you should be a little above the fingernail scratch test, but if they are crayon cast then they're definitely hard. You are probably not obturating and grabbing at the forcing cone causing skidding. Your leading will start at the forcing cone and trail an inch or so further down the barrel. I now use soft lead (1:20) for cast boolits and lyman #2 (approximately) for my harder boolits. I think you may be able to use a HB (#2) pencil to gauge the hardness, if it doesn't scratch the boolit you're way too hard (more than about 15BHN. I think fingernail is about 8BHN.

You need a special tapered plug to gauge the angle of the forcing cone, the ones I have seen are caliber and pitch (angle) specific, i.e. my .45 11* forcing cone will perfectly take a 11* .45 plug and it will sit flush at the barrel.

[Petrol & Powder]

I think you are on track. I wouldn't touch that forcing cone but as others have suggested your bullets may be the issue.
First, go softer with your alloy. 10 BHn is as hard as you want with target velocities and you can go lower.
Second, Pull a couple of bullets and check to see if your casing is swaging the bullet down. If you're shooting .357" bullets out of .358" throats, you're behind the curve before the bullet even reaches that forcing cone.
Third, if you're shooting commercial bullets at .357" diameter, hard alloy and hard lube - the forcing cone and throats are not the source of your problem.

[Lloyd Smale]

looks fine to me.

[Oklahoma Rebel]

I think they are probably right, youre boollits are not slugging up to form a seal at firing, causing gas to leak around the sides and that causes gas cutting and leading

[Forrest r]

Sounds like you need to get your bullets loaded out further in the cases. Flush is fine for semi-auto's but allot of revolvers do better with the bullets seated further out into the tapered cylinders. Some bullets loaded in 38spl brass for a 686, the 640's are crimped in the bottom crimp groove (bullet has 2 crimp grooves) and the h&g #50 is crimped in the middle lube groove. I've loaded the h&g #50's that way in 38spl cases for 30+ years for several different 357's.

http://i162.photobucket.com/albums/t242/forrestr-photo/8e26ef61-5d72-4232-9996-108bde84fb55_zpsymwzcftj.jpg (http://s162.photobucket.com/user/forrestr-photo/media/8e26ef61-5d72-4232-9996-108bde84fb55_zpsymwzcftj.jpg.html)

While not the most accurate or long range tested by any means. Those above bullets/loads do what they are designed to do. Shoot shotgun shells @ 50ft setup as bowling pins on the bowling pin table.

http://i162.photobucket.com/albums/t242/forrestr-photo/keepers_zpsrmfa629l.jpg (http://s162.photobucket.com/user/forrestr-photo/media/keepers_zpsrmfa629l.jpg.html)

When I load wc's in 357 cases I like to use a button nosed wc and crimp the button nosed wc in the crimp groove. A favorite 357/wc plinking load. A h&g #41 110gr wc doing 1300fps+ in either 6" bbl'd 357.

http://i162.photobucket.com/albums/t242/forrestr-photo/110gr357s_zps6cepphtj.jpg (http://s162.photobucket.com/user/forrestr-photo/media/110gr357s_zps6cepphtj.jpg.html)

All of those bullets pictured are around 9bhn and pc'd and sized to .358. I use/shoot/own 9 different 38spl/357 firearms and use these loads/bullets in all of them and have no leading issues. What the 686 looks like after a 200 round range session with those 38spl's pictured above.

http://i162.photobucket.com/albums/t242/forrestr-photo/686_zpseezfnjnz.jpg (http://s162.photobucket.com/user/forrestr-photo/media/686_zpseezfnjnz.jpg.html)

No leading and not much cleaning. Anyway you might consider taking a bullet and dropping it in your cylinders to see how far the flush seated bullets have to jump/freebore in your cylinders before they seal anything.

[M-Tecs]

Keep us posted on how you resolve this.

[44man]

PC is a full length GC!
I am going the other way to say if you have fit, boolits are way too soft and you are skidding. The gun looks fine. 62 or more years with revolvers I have never told anyone to make boolits softer.
Testing semi wad cutters only brought accuracy in at 28 to 30 BHN with zero leading.
BE, 231, etc has your boolits at near full pressure before out of brass so you are having silly putty at the cone.
The base band has engraved rifling larger then the barrel and gas blows past.
Slug up does not work, might seal throats but what affect at the cone and need to start to turn? You can't be too hard unless the boolit is under groove. You will never find lead so hard it does not expand to throat. Even jacketed will expand.
Put cardboard along side the gap and I bet you have holes in it from the putty squirting out from tons and tons of pressure. Make your boolits harder and harder and see what you get.

[Forrest r]

ya or it could be he's swaging the bullets down by using an undersized expander or an expander made for jacketed bullets.
or his cylinders could be oversized/max size and the bullets are swaged down when seating
or he might not be expanding the cases enough and he's shaving the bullets down when seating them
or it could be that that 2.7gr load of bullseye in a 357 case is in the 9,000+psi range and the bullet isn't expanding

Typical leading in the area he is getting is from undersized bullets.

And yes, pc is a full length gc:bigsmyl2::bigsmyl2::bigsmyl2:, but it also allows me to shoot @ indoor ranges.

[huntrick64]

After verifying your boolit diameter, don't forget your throats! If they are too tight, they can swage down the boolit small enough that gas blows by as it enters the (larger) forcing cone. That can cause leading in the cone. The diameter of the boolits is the easiest to verify first, then the dimensions of your gun. I'm not saying the hardness of the boolit isn't a factor, but I will say that if your dimensions are right, it probably will not lead from a soft bhn=9 to a hard bhn=22. I have solved a lot of leading issues in my own guns and ALL of it was dimensional related. Remember that the gun should continuously swage down the boolit until it leaves the muzzle. Then boolit should be the same size or slightly larger than the throats, the forcing cone should be a little smaller than the throats, the first part of the bore should be a tad smaller than the forcing cone, and the smallest part of the whole deal should be the muzzle.

[johnson1942]

i never ever knew what a forceing cone was untill i learned it here. my ruger old army has a large tapered one but not real polished. with a 45 long colt cylinder in it, it is very very accurate. shoots holes in holes.

[Petrol & Powder]

huntrick64, The OP stated that he had the throats cut to .358". What you said is accurate but I don't think the diameter of his cylinder throats is his particular problem.

[huntrick64]

Yea, I missed that part, even though it glared at me when I read it again. You are probably right that his boolit might be getting swaged down during seating/crimping. Something is causing it to not seal as it should. These things can be frustrating, and then it all seems to come together.

[44man]

I did not miss it and think the gun is fine. Now I use bullet expanders and make a tough enough boolit to be the final brass expander.
True the soft boolit can be sized when seating but to enlarge the brass to accommodate can lead to other issues.
The revolver was born from the fires of hell and years of pouring ice water down the hole has damped that guy down some. The devils head is full of lead so you need to outwit him.