RugerForum.com

This is a Ruger Firearms enthusiast's forum, but it is in no way affiliated with, nor does it represent Sturm Ruger & Company Inc. of Southport, CT.
It is currently Tue Apr 15, 2014 10:23 pm

All times are UTC - 7 hours [ DST ]




Post new topic Reply to topic  [ 9 posts ] 
Author Message
PostPosted: Thu Sep 17, 2009 1:41 pm 
Offline
Single-Sixer

Joined: Sat Dec 22, 2007 12:28 pm
Posts: 281
Location: Phoenix, AZ
After reading countless posts about forcing cones, hearing all sorts of conflicting statements, recommendations and opinions, it might be helpful to review what is actually known.

First, I would like to direct those interested DIY members to the Brownells info sheet that comes with their forcing cone kits. 76-200-152 is the number printed on the sheet, but currently does not show up on the Brownells site. This sheet covers more information than I have seen in one place about how to do it, why you are doing it, and how to screw it up.

As the info sheet points out, the f/c was developed to compensate for the fact that revolver chambers don't line up perfectly with the barrel. So, to avoid bullet deformation and even spitting out the sides the f/c helps direct the slug more politely into the barrel lands.

At this point we know what the f/c is supposed to do and why it exists in the first place. Only recently, as the sheet states, was a good deal of experimentation done by Ron Power as to the cone's effect on accuracy when changing the angle and depth using lead SWC ammo. So, for shooters who actually intend to use lead SWC ammo, go ahead and follow Ron Power's recommendations. Let me repeat one thing that almost nobody talks about: f/c depth. The info sheet talks about it, shows what is recommended, but does not explain the reasons behind it. However, it IS important. More on that later.

Then we come to the opinion department. The majority of people who post about forcing cones have cut their personal revolver or a small number of revolvers and reported that the accuracy was much better and leading was eliminated with such-and-such a f/c angle. Therefore, they claim that the angle alone is fully responsible for their great success. That thinking is flawed and here is the reason.

Taking Ruger revolvers as an example, most come from the factory in a very rough condition. They are full of gross shavings, burrs, and tooling chatter marks everywhere. Things get even worse in the f/c area. Now regardless of what angle (or angles) exist, a f/c cut with a hand drill with a 30-grit sandpaper finish is going to capture lead. Smoothing up that same cone with no other changes will take care of the leading problem. As to the improvement in accuracy - maybe or maybe not. One thing is for certain, any improvement in accuracy due to f/c angle (assuming that there is no gross b/c alignment problem) is going to depend upon bullet shape and material. So what is true for one bullet type will not hold for another.

Now what about f/c depth? Brownells thinks it is important enough to make special gauges (at $50 bucks each) to check it. They state that the rule of thumb is: f/c diameter at the rear should be no more than .020 greater than the diameter of the bullet. They even suggest that if the cone is cut too deep, you might want to set the barrel back and recut the cone. That sounds like a serious consideration to me, and I'd like to know a bit more on this subject myself. A makeshift gauge can be made with a fired case that is flared to the proper max. diameter.

Finally, if the f/c is cut correctly (using the .020" rule) at 5 degrees, it will be deeper than correct cones with larger angles. It will be impossible to cut an 11 degree cone of correct depth without creating a step from one angle to another. Sure you can cut until the step is gone, but your rear diameter is going to be much larger than the plus .020" recommended. Basic geometry, no magic. Since each Ruger f/c seems to be different, it may be possible to do the 11 degree cut without going too deep. It all depends upon what you start with. So, figure out what you've got first. Smooth up the existing 5 degree cone and compare the performance.

Let's get our ducks in a row, folks. Its truly amazing what can be accomplished by a little smoothing. Do you think the manufacturer is intentionally trying to make their revolvers shoot poorly? An 11 degree reamer costs the same as a 5 degree reamer. Just some things to think about.

Carry_Up


Top
 Profile  
 
 Post subject: forc cone
PostPosted: Thu Sep 17, 2009 3:28 pm 
Offline
Single-Sixer

Joined: Sun Feb 18, 2007 2:01 am
Posts: 293
Location: Hibbing ,Minnesota U.S.A.
How do you smooth up the forcing cone ?


Top
 Profile  
 
 Post subject:
PostPosted: Thu Sep 17, 2009 4:56 pm 
Offline
Hawkeye
User avatar

Joined: Sat Sep 30, 2000 1:01 am
Posts: 7083
Location: IL,USA
Well, all I know is I took my Old Model BH .45 Colt and re cut the forcing cone to 11°. The original cone was beat and battered by a cylinder out of alignment condition, and seemed to be pretty shallow.

I rented the forcing cone tool from Iowegan and followed his instructions. He said to basically cut until you have a clean forcing from from the opening to the rifling. Then stop.

The depth of my forcing cone increased by maybe 25% and the width at the opening did not increase. There was no compound angle either.

That's what I did. It worked. I shoot everything from that gun: round nose, SWC, jhp, and all in between.

Leading decreased, groups became more rounder and easier to do.

As for Brownells depth gauge Iowegan commented they rarely work properly as they usually show the factory forcing cone is too deep already. He did not have one to rent me, so I did not check it for depth with a gauge.

Sometimes people make things too complicated.

As for Ruger's factory forcing cone that is one place they could spend some more time, but unless damaged ( as mine was ) or badly cut, or full of tool marks, they usually don't need re cut.

Joe

_________________
Spare Cylinder & Custom Made To Order Bags by J Miller

***Be sneaky, get closer, bust the cap on him when you can put the ball where it counts ;) .***


Top
 Profile  
 
 Post subject:
PostPosted: Thu Sep 17, 2009 6:03 pm 
Offline
Buckeye
User avatar

Joined: Wed Apr 17, 2002 1:01 am
Posts: 1581
Location: Yuma,AZ
My Old Army had no forcing cone to speak of - the breech end of the barrel was beveled ever so slightly, but I would NOT dignify that by calling it a forcing cone. I piad to have one cut; the gun shoots ever so much better. Did the gunsmith over-cut the FC? I dunno. Did he use a gage? I dunno.

It DOES shoot better, and it no longer builds up lead at the FC. I'm satisfied. I'm NOT discounting the importance of these factors, by any stretch of the imagination. I'm simply saying that I doubt if most of us could recognize an over-cut FC - or the effects of same.

_________________
"Fleas can be taught nearly anything that a congressman can." - Mark Twain, What is Man? and Other Essays, 1917 ed.


Top
 Profile  
 
 Post subject:
PostPosted: Thu Sep 17, 2009 7:21 pm 
Offline
Single-Sixer

Joined: Sat Dec 22, 2007 12:28 pm
Posts: 281
Location: Phoenix, AZ
J Miller wrote:
The depth of my forcing cone increased by maybe 25% and the width at the opening did not increase. There was no compound angle either.


As I stated, each gun seems to come from the factory with a different set of dimensions in the f/c area. Glad yours came out fine, but it does not prove anything at all about the importance of checking what you've got before breaking out the cutters. I can't say what happens when the f/c is cut too deep (anyone know for certain?) but it does seem to be important. Obviously the bullet will still travel down the barrel.

Prove it to yourself gentlemen, cut a both a 5 degree cone from paper and an 11 degree cone. Cut them both so that the open ends are the same dimension and you will see that a 5 degree cone extends further into the bore. Those that have been lucky simply started out with a bare minimum chamfer and not a correctly cut 5 degree cone.

What we're trying to do is get past the mystery and magic and jot down what is actually known. What someone somewhere tried one time doesn't give me a whole lot of information to go on.

Carry_Up


Top
 Profile  
 
 Post subject:
PostPosted: Thu Sep 17, 2009 10:44 pm 
Offline
Hunter

Joined: Mon Sep 08, 2003 1:01 am
Posts: 2259
Location: Valley Center,ca.
Iowegan did a write up on this some time ago. (ruger forum.net)
I got the 38-45 forcin g cone cutter set from brownells and a set of Iowegans range rods (lucky me) Per Iowegans instructions every gun ended up better off.
I belive the 11degree cutter is recommended for Rugers.
I miss Iowegan but we have a good group of gunnies with us here.
Eric


Top
 Profile  
 
 Post subject:
PostPosted: Fri Sep 18, 2009 8:15 am 
Offline
Buckeye

Joined: Mon Jan 29, 2007 2:01 am
Posts: 1543
Location: Maine
Some people no matter "what" you tell them, are never satisfied with what they hear! So be it. As a gunsmith of 43 + years, I'm certainly not the best around but I can unequivocally say, that 11 degree reamer has cleaned up more bad shooting revolvers than I can ever remember! Believe what you will with your "theories" but the "proof" is in the pudding as the saying goes!.......................Dick :wink:


Top
 Profile  
 
 Post subject:
PostPosted: Fri Sep 18, 2009 9:29 am 
Offline
Hawkeye

Joined: Wed Oct 24, 2007 3:17 pm
Posts: 15090
Location: Kentucky
+1 for what Pinecone (& IOWEGAN) have told us.

I have used an eleven degree reamer on most of my centerfire Ruger single-actions, and in every case I have seen a reduction in leading in the forcing cone area, and a certain amount of improved accuracy in some cases. Nothing super-magic, but noticable.

The biggest improvement was in getting my .45 throats properly sized along with the forcing cone operation.

JMHO
:D


Top
 Profile  
 
 Post subject:
PostPosted: Fri Sep 18, 2009 4:38 pm 
Offline
Site Admin
User avatar

Joined: Mon Jun 18, 2001 1:01 am
Posts: 31584
Location: Star Valley, WY
I agree with the 11° figure and with the idea of fixing the Ruger .45 Colt cal. Cylinder Throats.

Sometimes the "homeboy" gunsmith can actually improve his gun.....

flatgate


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 9 posts ] 

All times are UTC - 7 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group