Forcing cone cleanup

[Tom C]

Tom C, Is that 5 degree included angle or 5 degrees per side?

Good question. I believe it is 5 degrees per side, but Brownell's sells two basic cutters, for various calibers, in 5 degrees and 11 degrees. The factory typically uses something around 7 or 8 degrees. The 11 degree cutter won't work. It will leave a two step forcing cone. Not good. The 5 degree will clean up the cone nicely. I have used it satisfactorily on all my .357 revos. I have started using it on my .45 revos as well. When I recut my 610 (10mm), I had to use both the .38 5 degree cutter and the .45 5 degree cutter. The original forcing cone was pretty bad. Now it shoots fine.

If I could get a good 7 or 8 degree cutter I would probably use that instead.

 

[browntown]

I *think* rugers are 5 degrees from the factory, but this is the first I've heard that you can't cut a good 11 degree cone on a smith. I'm an armchair gunsmith though, I have no experience actually twisting the reamer.

 

[Boge]

Good question. I believe it is 5 degrees per side, but Brownell's sells two basic cutters, for various calibers, in 5 degrees and 11 degrees. The factory typically uses something around 7 or 8 degrees. The 11 degree cutter won't work. It will leave a two step forcing cone. Not good...

Actually, the angles are reversed so an 11 degree cut is in reality a 79 degree, but that is hair splitting. I cut all mine with the Brownell's tool with the 11 degree cutter. I did it recently on a brand new 442-1 and it shoots a ragged hole dead nuts on with no fouling. A person does NOT need the plug gauges and all that other stuff, only the basic cutting tool, rod, rod guide & handle. It takes all of five minutes if that and is the best thing you can do a revolver IMO. I have never seen one make a revolver shoot worse and most times makes them shoot far better AS well as brings the shots into zero for windage as it trues up the bullet entry into the barrel.

I had a local gunsmith do mine for years and he only charged me $10. I watched him do it and he taught me how. It's not rocket science so I bought my own as I live only an hour from Brownell's. I don't have to monkey with Lewis Lead Cleaners anymore for that matter. Besides, using a tuft of bronze wool on a used bore brush is far faster for cleaning lead if you have it for that matter IMO.

Just remember that when using the tool that you are only trying to "true" up the forcing cone and not making a blunderbuss. You will know when pulling & turning the cutter when it smooths out that you are finished. Keep the cutter well oiled and only turn clockwise.

My best forcing cone story: in late 2007 I bought an Uberti revolver that shot about 5" left and several inches high at 7 yds. I proceeded to chamfer the forcing cone and it was THE roughest one I had ever seen (felt)!! It was like a mile of bad gravel road!! The tool chattered for several minutes cleaning out the rough spots. After cleaning up and giving it a good burnishing with the cutter head I went back to the range and all shots at 7 yds. (CAS distance) were in a ragged hole dead centered!!

If you own & shoot a lot of revolvers you need the basic kit IMO.

 

[WR Moore]

Those cutter angles are included angles. Once upon a time, the factory angles were in the 14-18 degree area.

If you're going to hack away yourself, the forcing cone shouldn't be more than 0.020 inches over groove diameter. Assuming a good quality revolver.

The qualifier is there because I learned why an H&R had such a large forcing cone from the factory. Barrel/cylinder alignment was .......casual.

 

[one eye joe]

The following is my opinion and only my opinion. I would suggest that you begin with a thorough cleaning of the throat, cylinder, etc. Purchase and use a Lewis Lead Remover as it will do this job completely

Do check end shake and head space before doing any work that is permanent. If end shake needs attention, deal with that using end shake washers (Brownells). If head space is a problem, I don't know what to tell you as I have no idea how to fix it.

Look at the throat. It appears there are machining marks present. If this is the case, you might first want to contact S&W and request that they correct this. Your revolver has a life-time warranty. As this would be a manufacturing issue, it would certainly be something that S&W would deal with. They might simply clean up the throat. Or, they might fit a new barrel. Bring to their attention the current barrel/cylinder gap of .007 inches and the lead spitting.

If you decide you want to proceed with chamferring the forcing cone, it would be wise to consider sending it to an experienced gunsmith/repair facility. You might get it right first time out the door. You might not. But an experienced gunsmith who has previously dealt with chamferring forcing cones and who has the equipment on hand would likely produce better results. Given the cost of the tool required, etc., you would likely come out with less expense. HTH. Sincerely. brucev.

Good advice, Bruce......

 

[ColColt]

I hope you have better luck with someone cleaning up the forcing cone that I did with a GP-100. Mine actually looked like someone cut it with a rusty auger. I gave it to a "gunsmith" who was reluctant to cut the 11 degree chamfer and only did it piecemeal awaiting my approval. I finally(after two visits) just got it back from him. He never did it to my satisfaction but it did look better than before. My problem was leading...only at the forcing cone and that was why.

Before

After

 

[gtoppcop]

Joshua,

Good info by all. Whenver I get a revolver, I routinely have the forcing cone cut to 11-degrees. I have a few that have 18-degree cuts. I haven't had any leading issues with them.

I would send the revolver back to S&W (Jim Rae: [email protected]) to have the B/C gap corrected and troubleshot.

When I reload, I have used hard cast and swaged lead, but lately have gone to Berry's bullets. As long as you don't drive them too fast (over 1100 fps) they are very clean.

S&W is usually very good about sending you a FedEx sticker and getting the gun back to you in short order.

Something to think about... Good luck with your revolver. I'm sure all will come out well enough.

-Greg

 

[browntown]

Thanks Greg, the gun is at S&W right now, and I'm assuming they're doing what they need to because they haven't sent me a notice that I need to pay for anything. I'll report back when I get it and shoot it.

I'm still considering buying the tools to cut my forcing cones to 11 degrees. I'm pretty well committed to the 38/357 guns so I could use the tools on several guns to spread the cost out.

 

[Hoogs]

I use and highly recommend "Birchwood Casey Lead Remover and Polishing Cloth"... works a charm

 

[browntown]

So it's been over a month and I just got a letter from S&W talking about all the work to be done including fixing the timing, resetting the barrel for what they deem as am * in tolerance *cylinder gap but "could be improved".

Oddly, they're asking me to sign off for over 100 bux in labor charges. I'm going to have to give them a call to better understand how a gun which doesn't shoot right sent back for warranty work comes with a bill.

I'll report back.

 

[Frank46]

ColColt, the after pic of your GP100 reminds me of an old well broken in rifle bbl. No insult intended. I have an old mauser in 9.3x57 and soon as I saw your forcing cone pics I thought of that. The old mausers had long gentle throats that better guided the bullets into the rifling. Much like what we try to achieve each time we pull the trigger. Sometimes it works and sometimes it doesn't. If Joshua continues this thread after he gets his revolver from S&W this will be a very interesting thread. I hope he does. Frank

 

[ColColt]

I think what you're seeing in mine is due to lack of depth of field with the lens and a not so steady hand at 1/60th sec. Using a macro(60mm f2.8) at f8(I think it was) doesn't show all the detail but blurs it somewhat. It ain't perfect but a sight better than it was.Use to I couldn't get six rounds through it without apparent lead in the cone and for about half an inch into the rifling. Throats are .358" and I used both .358 and .359" bullets-nothing helped until it was cleaned up a bit.

 

[browntown]

I called them up today, and was told because I was not the original owner that the warranty does not apply. Not thrilled about that but for about $100 they are fitting an over-sized hand, redoing the timing, turning the barrel and fixing the cylinder gap. We'll see if they work on the forcing cone or not when I get it back. It'll probably be another month before I get it back. I'll report when I get it.