Reaming and lengthening forcing cones is subjective, some think its a complete waste of time and money while others including me think long cones reduce felt recoil and may in some cases improve patterns.
I can this, I had a Perazzi with small bores and tight chokes that would knock me out out of the county shooting 3 dram target loads every time I pulled the trigger. I tried different stocks and recoil reducers with no avail. A friend talked me into having the cones lengthened, the results were amazing, the beast was tamed. Almost every gun I've owned since have had their cones lengthened.
People, who may be influenced by the fact that they just paid good money to have their gun modified, and by golly it had better work, may believe differently.
If it does reduce recoil, and I'm not saying it does, its not by much.
Here's what is guaranteed to reduce recoil:
- Add weight to your gun <br>
- Reduce the muzzle velocity of the shells you are using <br>
- Reduce the shot payload of the shells you are using <br>
- As was mentioned above, make sure your stock fits you properly
Any one of those will have a bigger effect than you can get by having your forcing cones lengthened.
And there's no proof that lengthening forcing cones has any effect on patterns either.
Indeed, a clever fellow named Neil Winston proved it had no effect on an 870 barrel he tested.
One thing it is guaranteed to do is this; weaken your barrel.
Think about water venturies, or ask any HVAC guy who knows about air flow. You are eliminating/reducing the "abruptness" of diameter change from the shell's ID to the barrel's ID, AND you get less distructive forces applied to the wad, and less shot deformity due to the reduction of forces applied to the captive shot. It provides a better dynamic change to the shot and wad.
Most high dollar guns already have the F/C elongated.
I recently switched to a Kolar with 0.750" bores and the forcing cones are almost non existant. The gun seems to recoil considerably less than my old 682 Beretta which was a simlar weight gun. Now there may be alot of other factors at play but I think there is something beneficial about the increased bore diameter and gradual forcing cone.
Being former student of physics, this seems a bit counter intuitive but then again I am probably not completly aware of all of the forces involved.
I wouldn't modify a barrel in this manner but if the manufacturer can supply a barrel like this then okay its worth a try.
Whiz, with all respect, I think I understand physics pretty well.
You're comparing apples and accordions.
The only way lengthening forcing cones CAN reduce recoil is if, all else equal, it somehow reduces the muzzle velocity of the shot. The vast majority of what you feel as recoil happens after the shot has left the muzzle.
And the shell's ID and the barrel's ID are very nearly the same! The forcing cone is only there to transition from the shell's OD to the barrel's ID.
The only reason barrel manufacturers have started including long forcing cones is marketing! Its because people think it will buy them targets and reduce recoil, but there's no proof to either claim.
If you read Neil Winston & Don Zutz's study results after their extensive tests on Forcing cones, you'll see said long forcing cone theory has very little to do with reality. In Don Sutz's test, it even produce less % in pattern.
I don't like thinning the most critical section of the barrel by an after market work. But I have no problem buying a factory barrel with longer forcing cone, if it doesn't cost me extra.
I actually have an undergrad degree in physics and mathematics.
I am NOT comparing anything wrong. What you are talking about is possible the muzzle velocity only, but what I am talking about is the moment of inertia. The LONG you phase through the recoiling action, the less there is FELT recoil.
You can talk all day about velocity reduction, etc. but as long as you STRETCH OUT the moments of inertia in the reaction, the less there is FELT RECOIL.
Neil's study, if my memory serves me correctly, measures the reactive force, but NOT the moments of inertia.
Regarding the "thinning of the barrel", I have removed forcing cones from guys trap guns who have shot with me over a 30 year period of time. I have failed to see ANY negative results from removing metal at the forcing cone. And, in fact, by elongating the forcing cone area, you have what amount to less force-time applied to the barrel in that area. Think about it...
Regarding removing forcing cones as a marketing ploy, I have never read where any manufacturer, particularly Perazzi that has ever mentioned this in an advertisement. Maybe Mossbery, or the likes. One thing I can tell you is that I will not do this work on Remington barrels, not for any other reason than their barrels are so damn hard... and we're only talking about a couple thousandths of an inch.
I have done it to several guns with a great difference in some and little in
others. It is not expensive, I have used famous gunsmiths and none have
concerns of barrel thickness (you are only removing a restriction, but no material before or after the restriction). The gun that I felt the most
improvement was a Browning Superposed Lightning Trap. I could not finish
50pr of doubles with out a very sore shoulder, lengthened forcing cones and
shot 300-400 per day in Sporting Clays. My daughter now shoots 300-400 per
day sporting clays with no other changes. Many talk about the velocity and
recoil, but few mention acceleration and its effect. It worked for me on some
guns and no downside other than a few dollars to try. It is the first thing
I would try after gun fit. Gary Owen
As opposed to any "before and after" experiments to determine if longer (relieved) forcing cones make any difference, I did some simple experiments with a Beretta 682.
After obtaining a set of 30" optima barrels that closely matched the 30" mobile choke tubes original to the gun, I tried some different loads through each barrel.
Both these barrel sets were similar weight, length, and even the bore I.D. of 18.5 (about .730). The newer barrel set uses a slightly different rib.
Although I could feel differences in going from 7/8 to 1 to 1 1/8 ounce through either barrel, I couldn't feel any change going back and forth between the barrels with similar loads. Mind you the Optima bore has a very different forcing cone compared with the Mobilchoked barrel, the difference is most obvious, not only measuring but also when in viewing from the breech end.
These tests were done on the same gun, stock, forend, - same day with loads all from the same boxes, so its safe to say there is not much difference that I could find, and if there is, it is much less than going up or down an eighth of an ounce in lead.
Some of the great barrelsmiths might be able to achieve better results; even Beretta is making great claims about the new tri-bore DT-11, though that gun is more of a total package. GAP
hmb, That's the stupidest thing I've heard you say on this forum. Go look up "hoop stress" in a mechanical engineering handbook. If the barrel wall is thinner, its weaker. Remove metal, you remove strength. If you apply the same pressure to it, the stress must be greater on the thinner wall tube. Unless you are implying that the larger internal volume reduces the peak pressure, in which case I will ask, how do you know? Have you tested it?
Whiz, we're just going to have to respectfully agree to disagree. Browning makes a big deal out of it. Beretta too. In fact I beleive their new steelium barrel in the DT-11 has the forcing cone the entire length of the barrel. I think its just marketing. I too have a little background in applied physics as a mechanical engineer. Most of it in fluid flow (water and steam in pipes and air in ducts.) So I understand yout analogy quite well, but I disagree that the comparison is valid.
And if we're talking about "felt recoil" I think my point is even more valid because most of the recoil you "feel" happens after the shot/wad has left the barrel, so it is extremely difficult for me to believe that what happens in the first 6 inches of the barrel can have any effect on "felt recoil." Because in that short span of time, you haven't felt anything yet. And by the time you DO feel anything, its all down to momentum; M1V1 = M2V2.
Greg, I truly believe what is going on is your Kolar big bore barrel causes the same shells you were using in your Beretta to have a slightly lower muzzle velocity and/or the Kolar just fits you better.
That's my opinion. You know what they say about opinions...
tmb99, can you tell me why? I have a factory Beretta 303 with a 30" trap full barrel and a 30" big bore barrel with the same % of restriction. Through the chronograph, using the same loads,The big bore barrel shoots faster and felt recoil seems to be less? Bill Hom
I have done a few and noticed some difference in patterns in some of them and not in others. One factor we may be ignoring is that I polish the bbl after cutting the forcing cone with a dingleberry hone from Brownells. I assume the pros do as well. Perhaps that has a bigger impact than anything else. At my stage in life, I am too old to care.
You can't really remove the forcing cone, per se, but he's probably talking about having it extended using a reamer.
The forcing cone is the tapered part of the barrel that transitions just after the chamber, between the diameter of the chamber (about 0.800 inches), and the diameter of the barrel (usually about 0.729 inches, but not always.)
If your barrel truly had no forcing cone, the entire barrel would be 0.800 inches. Which has been done, but is uncommon.
I have a factory K80 barrel that is .800 bore. It is one of two made over 20 years ago. Thirty inch forcing cones. I have the identicle barrel in standard form. There is very noticeable reduction in recoil. Jeff