Reaming the forcing cone out to 11 degreesforcing cone

[rde1911]

I saw a you tube video of a gunsmith reaming the forcing cone to 11 degrees and at the same time smoothing the first edges of the rifling in the barrel. They said it would make the pistol more accurate shooting lead bullets. I did a search on the forum an did not find any information about this.
Here is a link to the you tube video.
Revolver Forcing Cone Tools - YouTube
Thanks

 

[TAROMAN]

Thanks for the link.
I have the Brownell set for this, but lack the plug gages to check the work and know when to stop,

 

[chief38]

I have two guns with forcing cones that I reamed to 11º and truthfully I can not really tell any difference in accuracy. MAYBE a slight bit less leading, but I can not discern any other major benefits. Unless you are having issues with your revolver I'd just leave well enough alone.

Sometimes I think GS's, equipment & tool manufacturers just invent new ways to make more money. Maybe technically on paper some of these procedures make sense, but in the real world I have not seen enough evidence to make this worth while. Like I said, I've got 2 guns that had this and there's no big difference.

 

[OKFC05]

Maybe I'm a pessimist about "improving" guns pointlessly because the number one reason for people dropping out of my IDPA Matches is the guns aren't broken until they "improve" them.

If somebody who knows what they are doing reams the forcing cone correctly, it does no harm and may help, but do you know what a mess you have to fix if you go just a little too far?

 

[chief38]

AND......... what I'd like to know is that IF 11º is such an improvement over Factory specs, why don't the Factory's just cut them to 11º????

 

[bgrafsr]

AND......... what I'd like to know is that IF 11º is such an improvement over Factory specs, why don't the Factory's just cut them to 11º????

I believe 18* is for both lead and jacketed, but I'm not positive on that. As far as I know, Ruger cuts there forcing cones to 5* on the double action revolvers, and 10 to 11* on the single action guns.

 

[KLNFrame]

That man in the Video has no idea what he is doing.
Without plug gauges it's just a guess and maybe a ruined forcing cone or barrel.

 

[Nemo288]

I have only ever had one throat reamed. It was part of an "action" package.
This was done by MagNaPort. Even when done by pros, there are still some machine marks.
The scoring is not as deep but still noticeable.
The trigger job (and porting) did make the gun more comfortable to shoot,
but in all honesty I can't say the throating made ME shoot any better
It did help some with leading in the 3/4 loads (lead at 25 and up kpsi).
My Redhawk, L Frame 44's and 624's shoot lead so well, I have never been tempted to do this again.

===
Nemo

 

[rde1911]

I think these two statements make a lot of sense.

"Sometimes I think GS's, equipment & tool manufacturers just invent new ways to make more money."

And

"I'd like to know is that IF 11º is such an improvement over Factory specs, why don't the Factory's just cut them to 11º????"

For the guys that have paid to have the work done, It does not sound like there is a lot of Bang for the buck..

Thanks for the feedback.

 

[Big Cholla]

I'm an old pistolsmith that cut a lot of forcing cones to 11 deg. as requested by the owner of the revolver. I found in testing that any revolver that was shot with a lot of lead bullets cut down the side spitting of unburned powder and lead after the forcing cone was cut. Also, those revolvers stayed cleaner thru a lot more use than the uncut. They minimized the lead buildup oft found under the top strap. I found that 38/357 benefited the most, 45 cal. the next and 429 (44 spec. and 44 mag) the least. As far as accuracy went I never saw any determinable improvement from the recut of the forcing cone. But, I also never saw any decrease in accuracy either.

I soon determined that if one was shooting FMJ or Semi-jacketed bullets recutting the forcing cone was a waste of time as long as the revolver barrel had at least a token forcing cone.

The job is not difficult to do correctly and should not be a huge charge from a reputable gunsmith. I cast most of the bullets that I shoot thru my 38 Specials, 357 Mags and 41 Mags and I make sure that all of those revolvers have the recut forcing cone.

I do not watch random DIYS gunsmithing videos on the internet as I find that most are a huge waste of time. I have watched a couple on the recommendation of learned friends. That is where I learned about the use of 'Simple Green' for cleaning purposes.

If I have learned anything in the years that I worked on factory handguns it is to never trust that every machining operation was done to every handgun exactly to OEM Engineering Specifications. I have corrected at least one 357 revolver barrel that had NO forcing cut at all. I corrected at least one 38 Special revolver that the cylinder had been chambered for 357 Mag. Responsible gun ownership involves checking everything about your handgun, especially one that might be intended for self defense purposes. ............. Big Cholla

 

[Nick B]

I have only ever had one throat reamed. It was part of an "action" package.
This was done by MagNaPort. Even when done by pros, there are still some machine marks.
The scoring is not as deep but still noticeable.
The trigger job (and porting) did make the gun more comfortable to shoot,
but in all honesty I can't say the throating made ME shoot any better
It did help some with leading in the 3/4 loads (lead at 25 and up kpsi).
My Redhawk, L Frame 44's and 624's shoot lead so well, I have never been tempted to do this again.

===
Nemo

Yea but we're talking about forcing cones here, not cylinder throat reaming .

 

[Nemo288]

So was I. (check the pic I posted).
Maybe my choice of words wasn't perfect.

===
Nemo

 

[MSgt Dave]

Forcing Cone Issues

I am the second owner of a S & W Model K 15-4 that I have been the only shooter except one box before the prior owner traded it in on a 357 mag. He said it was to light. It was made in 1976 according to S & W numbers. I bought it in 1981.

It is on it's second cylinder. Sent it back to S & W a few years back asking them to go through it and I know it definitely needed a cylinder as light loads were hard in extracting. They sent it back without doing anything as they didn't have parts for anything this age???? On to Brownells for a cylinder and a few other trigger parts.

Biggest problem I have had with this revolver is leading to the left and right of the forcing cone. I size my home brew bullets to .357. Even with the original cylinder, it did it.

After reading and learning about reaming the forcing cone, I think I'm ready to do it. I plan on doing the 11 degree verses S & W's 8 degrees.

Thanks for all the help and info!

 

[steelslaver]

I have an 11 degree cutter and lap, and I just cot one for 22 and 32 barrels but only for when I make a barrel , turn one back or install an longer 45 colt cylinder and use and acp barrel which needs the extension trimmed. If I had a gun that was leading or spitting and the chambers aligned I would try it. But, for the most part if it ain't broke don't fix it. Most of my guns shoot better than I can so until I can figure out how to fix me I won't try to wring out more accuracy. You can make your own gauge BTW

 

[trulyapostolic]

Like already mentioned a cleaned up forcing cone will probably be much smoother than the rough job S&W does. The very best forcing cone is a Taylor Throat. It allows the bullet to be free of the cylinder and align before hitting a gentle 1.5 degree leade into the rifling. Requires a special cutter though.

 

[minconrevo]

It is very easy to go too far when cutting a forcing cone. Also easy to get in trouble when trying to square the forcing cone. Less likely to get into trouble when using a brass lap tool and some mild rouge.

 

[MSgt Dave]

Forcing Cone reaming.

Well, I did it at 11degrees. Rented the reamer, guides and handle for $48.37 from 4D Reamer rentals. You get one week for reaming and a week to mail it back
Cost me $13.90 to mail it back via Priority Mailer box.
Total cost less than the cost of buying something I will never use again as I do more semi-autos now.

Took me about 25 minutes to do the first one, my 15-4. Looked great,, still got just a little shaving as I went as light as possible.
Did a second trim, and nothing now. Accuracy is better than before and no leading.
So, I also did my Dad's 1957 15-4. Clean shooting now as it had some leading on it from shooting lead bullets. It also shot better and clean as a whistle. His took me only about 15 minutes to do now that I knew what to do.

If I take a sized polymer bullet, they drop in almost to the first lube ring on 158 gr SWC.

Forty year issue finally solved. Thanks for all the info and advice.

 

[WR Moore]

There's another thread where someone made a comment about the angle of the forcing cone being less important than the surface finish. That's probably the best summation on the issue.

I do believe the PPC crowd figured out that at least with lead wadcutters the 11 degree forcing cone had some slight advantage. Probably only a very slight advantage that could/would be off set by the human holding the gun in competition. The 18 degree forcing cone is considered the better choice for jacketed bullets and is at least decent with lead. See paragraph one.

Back when I did barrel work, I wouldn't ream the forcing cone, I cut it on the lathe. But then I wasn't doing production machining.

 

[MygunisaS&Wrevolver]

Would anyone know about the Brownells forcing cone gauges? I have one that's for .357 and it's marked 18 degrees and I have the 11 degree forcing cone cutter. Should I find an 18 degree cutter to prevent the possibility of creating a compound angle which could effect accuracy? Or would the 11 degree cutter work fine with 18 degree gauge?

Thanks in advance for any info!

 

[Ron IL]

Rugers are the worst. I did my GP100 and it helped leading on the forcing cone a bunch. Using a bigger bullet cured the barrel leading. The most good was from reaming the cylinder throats. It had at least three different sizes of cylinder throats. My Smiths were all OK on that. Didn't have to touch the Smiths. Here is a link to the Ruger forum where they talk about this a lot. RugerForum