What is a lengthened forcing cone & backboring?
- Thread starter Kestrel
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The advantages are supposed to be a tighter pattern and less recoil; they force the shot into the bore more gradually, resulting in fewer deformed pellets on the outside of the shot column, and because it happens more gradually, over a longer distance and time, the immediate "slam" of the recoil is supposed to be lessened. HTH.
The forcing cone is the area in the barrel from the front of the chamber to the actual bore. It is tapered and (as mentioned in the previous post) is the area in which the shot, having been expeled from the shell, is forced into the bore. The longer, and less drastically angled, the forcing cone is the less damage is going to be done to the shot column and the less force is going to be spent in that area (which should reduce felt recoil).
Backboring is the opening up of the actual inside dimension of the barrel's bore. There are a couple different formulas for the optimum dimension. Which you choose depends on who you believe has the right numbers. The late Stan Baker was probably the foremost proponent of this practice, but it has gained enough respect that even the new manufactured guns have started to come out with barrels that are built to the wider dimensions.
It should be noted that if backboring is done correctly the chokes will also need some work. Remember that choke is measured in terms of constriction, and if you change the diameter of the barrel without changing the choke you in effect increase the amount of constriction, and therefore the choke.
Backboring is the opening up of the actual inside dimension of the barrel's bore. There are a couple different formulas for the optimum dimension. Which you choose depends on who you believe has the right numbers. The late Stan Baker was probably the foremost proponent of this practice, but it has gained enough respect that even the new manufactured guns have started to come out with barrels that are built to the wider dimensions.
It should be noted that if backboring is done correctly the chokes will also need some work. Remember that choke is measured in terms of constriction, and if you change the diameter of the barrel without changing the choke you in effect increase the amount of constriction, and therefore the choke.
Will backboring and lengthening the forcing cone interfere with the proper operation of recoil-operated shotguns such as Remington's Models 11 and 11-48? For example, might these modifications increase the occurrence of FTE or FTF? I hope not; these mods sound like a great idea.
Backboring and a long cone are what should wait until one's proficiency level is such that only an equipment upgrade can improve scores. Until that happy day, BA/UU/R does oneheckuvalot more.
Keep an eye out, sometime soon I'll have "Mods and Accessories 101" up. All will be explained to the uninformed...
Keep an eye out, sometime soon I'll have "Mods and Accessories 101" up. All will be explained to the uninformed...
So, lengthening the forcing cone helps prevent shot deformation, thereby improving patterning and also reduces felt recoil. Good.
I'm not sure I understand excactly what backboring does, though.
Thanks,
Steve
I'm not sure I understand excactly what backboring does, though.
Thanks,
Steve
Thanks, Dave.
I guess I'll just BA/UU/R with the 1100 until I'm really, really good, then. Too bad that the 11-48 fits me so well. I can put more shells through the 1100 before fatigue sets in, so that must be the right answer.
I guess I'll just BA/UU/R with the 1100 until I'm really, really good, then. Too bad that the 11-48 fits me so well. I can put more shells through the 1100 before fatigue sets in, so that must be the right answer.
Backboring in conjunction with longer forcing cones will reduce felt recoil and will cut down on friction in the barrel allowing more velocity. We're only talking a few thousandths relief in the barrel. This practice does not help if shooting the promotional shells that have a filler wad behind the shot column as it won't put a good gas seal in the barrel. The use of plastic wads is the only thing that produces the tight gas seal at the base of the wad column. If you remove a plastic wad you will notice that it is tapered up so that when the powder ignites it swedges the taper out to the side walls and gives a good seal. On standard barrels the entire wad is snug in the barrel, in backbored barrels it is only the the back base of the wad has the most seal on it.
Just relieving the forcing cone is usually worthwhile, while backboring has its place, mostly in target guns all it adds is a bit more velocity due to less friction and a bit better and more even pattern.
Bob, you can be happier yet. Measure the important stuff on that 11-48 and duplicate the LOP, drop, pitch, cast, on your 1100.if you find this challenging, any decent smith can do it for a price.
And, going to lighter loads in the 11-48 should fix you up there.
HTH...
And, going to lighter loads in the 11-48 should fix you up there.
HTH...
I always lengthen the forcing cone on my shotguns. I have found that it does help to give a more uniform pattern, and it can reduce "felt" recoil. I have not found any downside to this, and have repeatedly asked manufacturers why they do not do this on their modern shotgun barrels. (I have yet to get a good reason from any.)
The longer forcing cone will not interfere with the operation of any of the Remington 11-48, 1100, 11-87 series guns. They are gas operated, felt recoil changes have no effect on their operation.
The longer forcing cone will not interfere with the operation of any of the Remington 11-48, 1100, 11-87 series guns. They are gas operated, felt recoil changes have no effect on their operation.
I also had the forcing cone lengthened on my Model 11 when I had the barrel cut for removable choke tubes. It produces very nice patterns. Don't have anything to compare it to for recoil.
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