SBH Forcing Cone Flame Cutting

[mattd]

I’ve got a bit of flame cutting, but just at the top of my forcing cone. It’s only 20 degrees left and right of top center. The rest looks fine. I only have seen it be the full 360 degrees before. What’s that mean?

The inside of the FC looks pretty good. I can still see the tooling marks. Just a tad of erosion at the top in the same area as the flame cutting.

Just a bit on the top strap too. ~1/8” wide. Not real deep.

[osteodoc08]

Lil Gun or 296

[mattd]

I’ve shot less then a pound of 296 thru it. Not sure about it’s previous life. But why isn’t it all the way around the FC? I was thinking something might be misaligned.

[mattd]

I’ve never been able to get this thing to shoot. I’ve shot one box of cheap Herrters ammo when I first got it and cast ever since. Pretty much always gas checked, Thompson or 310 lee. Lots of diff lubes, lots of diff loads, lots of diff alloys. Sized .4315. Always leads...a lot.

Been awhile since I measured it, probably never all important dimensions at once. Smallest cyl is .4312. Slug pushed all the way thru barrel is .4294, altho one groove is .4298. Slug pushed into 1” of muzzle is .4300, although one is .4298.

So probably a candidate for fire lapping? Although, when pushing a slug all the way thru, the resistance at the threads is significant. Wouldn’t have thought .0006 would make that much diff.

So, maybe the weird, asymmetrical firecutting on the face of the FC is the real problem, and I’d appreciate any input into that. In the meantime I’ll fire lap and if that solves the leading/accuracy problem then I’ll just keep an eye on the FC.

[ShooterAZ]

Before you take more drastic measures, please tell us about the loads you are using, powders, charges, lubes, boolits/alloys etc. Like to know your loading procedure, how you flare your case mouths and seat & crimp boolits. Something is way wrong if it always leads! Give us a little more info, and we can hopefully steer you in the right direction. What are your accuracy standards? I never met a SBH that couldn't be made to shoot decently.

[mattd]

My accuracy standards would make you guys laugh. If I could do an inch at 15y, 2 at 25y I’d be happy!

Your asking for 5 years worth of info. But here goes....

Have used the GC Thompson bullet, GC 310 lee, 200 lee, commercial Cast Performance 255g.

Have used ACWW, WDWW, AC and WD 50/50. Have used diff alloys a bit softer and some a bit harder.

Have used 50/50 lube, Carnuba Red, white labels 2400 (I think that’s what it’s called).

Have sized 432 and 431. My 431 actually is 4315. And if I remember right the 432 was a little bigger too.

Have tried a bunch of loadings. Low and slow, mid range and high end. Using Unique, 296, 2400, Blue dot, #9.

Today I scrubbed it like crazy w an old brass brush w brass scrub pad around it. Got it really clean. 5 shots with ACWW Thompson bullet w GC, 2400 lube, 10g unique and it was full of lead. Always right in front of the forcing cone, and following the rifiling for an inch or so.

[Mal Paso]

The rear face of the forcing cone was not cut 90 deg. on a Colt that have. An inexpensive auto feeler gauge could tell if the cylinder gap is wider on one side. Gas cutting usually follows the easiest path. The face of the cylinder can also contribute to gas cutting.

I used a stone and roller guide to square the barrel on the Colt, no gas cutting before or after. Gap was .004 or less to start so no barrel reset.

My S&W 629-6 is a study in gas cutting. The rear end of the barrel is thinner than my other 44s and the cutting corresponds to the thin face of the cylinder at it's outside edge. The cutting is within about 30 deg. of vertical both ways.

[nicholst55]

If I was really worried about it, I would either have a good gunsmith set the barrel back a tad and recut the forcing cone and refit the ejector housing, or send it to Ruger and have them replace the barrel.

[Bookworm]

You have already acknowledged the first problem, which is thread choke where the barrel screws into the frame.
Either have the barrel replaced, or lap it out.

I think you have a second problem. Have a 'smith check cylinder to frame alignment. I think one or more chambers are misaligned with the barrel, causing the bullet to slam into the forcing cone from one side (or top). This could be causing the uneven erosion of the forcing cone.

[ShooterAZ]

I agree, leading at and in front of the forcing cone is indicative of excessive thread choke. You could try lapping, and if that isn't successful I'd send it back to Ruger.

[rockrat]

The lapping sounds like a good idea for you. With gas cutting at the top of the barrel, the end of the barrel might not have been cut perpendicular to the bore and you have greater barrel/cylinder gap at the top of the barrel. Also could be the face of the cylinder might not be perpendicular, even if the end of the barrel is. I would send the gun back to Ruger (ask for prepaid shipping box) for a re-barrel and have the cylinder checked too. I have an older SBH with 20K rounds on it that looks better than the end of your barrel

[mattd]

I can’t find my feeler gauges. Gonna get a new set, but in the meantime I can eyeball that the cyl gap is larger at the top then bottom. And it looks like the forcing cone is not perpendicular, versus the cyl.

This gun is from 1978. What should I expect from Ruger? They replace the barrel for free and cover shipping? That seems wild, but would be awesome.

Let’s say I fire lap and leading goes away and gun is great. Should I still send it back with the forcing cone issue? I’m guessing the new barrel could easily have a thread construction and would need lapped.

[rockrat]

A new barrel might have a restriction too, and you would have to lap it. I would call Ruger first and see what they might say. If its on their dime, then I would go that route, if your dime, try the lapping.

[LUCKYDAWG13]

I can’t find my feeler gauges. Gonna get a new set, but in the meantime I can eyeball that the cyl gap is larger at the top then bottom. And it looks like the forcing cone is not perpendicular, versus the cyl.

This gun is from 1978. What should I expect from Ruger? They replace the barrel for free and cover shipping? That seems wild, but would be awesome.

Let’s say I fire lap and leading goes away and gun is great. Should I still send it back with the forcing cone issue? I’m guessing the new barrel could easily have a thread construction and would need lapped.

I sent a 12 year old SBH back to Ruger to fix front sight that was put on wrong by the factory they did do it for free but it took a lot of
talking to get them too they wanted $175 to replace barrel and re-blue my gun but like i said they did do for free

[Tatume]

I agree that starting a conversation with Ruger is wise. They will take the gun back and fix it, but they may or may not charge you. The information gained is worth the phone call, either way.

[mattd]

FC to Cyl measures .004 at the top. A .0015 will get stopped at the very bottom. So it transitions from less then .0015 at bottom to .004 at top.

I called Ruger and they didn’t hesitate to say ship it in. But that’s all they said. They said they’d send me a shipping label for $30. They’d have a look and let me know....something? The lady didn’t really tell me what they’d check. Guess if it’s safe or not. Not sure if I should spend the money and not have it for awhile just to have them tell me it’s fine and within spec.

[metricmonkeywrench]

Not to hijack the tread but get a better understanding what does flame cutting all the way around the FC indicate?

[jrayborn]

I suggest that you send it in. They will do their best to satisfy you.