doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com fixed choke fixer type?

I recently purchased a bore gauge to figure out why my double patterns great in one barrel and horrible in the other. Right barrel has even dispersal, good density, hits targets clay and feathered hard. The left barrel which is bored tighter is sparse and uneven. I noticed with the bore gauge while comparing chokes and bores that the right barrel has 3/4" of consistent measurement at the muzzle (only significant difference I can see). The left barrel continues to taper to the muzzle with no parallel. It kinda makes sense to me that this is the cause of the poor patterns. Will I benefit from boreing the choke to duplicate the 3/4" parallel section at the muzzle?

If it tapers to the muzzle it would have to be opened quite a bit to get a parallel choke. Or, send it to Briley and they could install parallel screw chokes in that barrel. Or, maybe Mike Orlen could also do it cheaper and faster.
I don't know what shells you are using but some guns pattern much better with a little slower shells. www.rstshells.com or www.polywad.com They will get the job done.

Lefever made quite an advertising topic, about their "continuous taper" chokes. Winchester did it for years. Now, Teague has "invented" their continuous tapered choke tubes and is very proud of them. I doubt that your problem is caused by the lack of a parallel section. I agree with Patriot that your problem should be handled by an expert. Best wishes with it.

Thanks for the replys. The gun is a LC Smith 12 ga about 1949 vintage. The best patterns I have gotten out of the left barrel was with my 12 to 20 ga chambermate using a 20 ga skeet load. Fewer pellets lesson the condition and improve density of the pattern.
A continuous taper seems counterproductive--pellets would be converging at a central point causing deformation. I wonder how they get away with that. My Winchesters all measure with a parallel section, most of them longer than 3/4". I will give Mike a call to see what can be done to improve it.

Lefever's Full choke in a 12ga generally ran about 4" long & had around .032"-.035" of constriction. Many full choke 12ga's of the era had about .040" constriction with a cone length of about 1½" or less followed by a 3/4" parallel. It would seem if anything the more gradual taper of the Lefever choke would give less deformation than the sharper cone of the parallel type.
It is though I believe quite unusual to find an LC Smith with a taper choke. Quite possibly the choke reamer was run too far down the barrel thus eliminating the parallel but still having the abrubt cone taper. As stated though to get much of a parallel much of the choke will be removed, so you will have to consider if this is acepable for your purposes. The original Win-Chokes at least had their entire choke within the confines of the tubes which ran to not much over 1½" & seemed to work well for most purposes.

Thanks Piper. With the right barrel having a parallel and the left not I kinda thought it was a fluke. I have measured the bores and chokes for all types of things to find the differences. If I duplicate the 3/4" parallel in the left barrel I will take the slightly tighter than full barrel and open it to light full. If it doesn't work I can duplicate the right barrel and have Imp Mod in both. This has been a project gun for me I would like to do all the work myself.

Be extremely careful in opening a choke with no guiding parallel. Your reamer "MUST" be given some form of mechanical guidance to keep it aligned with the bore. Don't let anyone tell you that you can simply use an expansion reamer from the muzzle & "Eyeball" it.
This has been done quite successfully when there is already a parallel section to follow, but a continous taper to the muzzle is an entirely different proposition.

The lack of a parallel section in the choke is not your problem.
Both Fox & Parker used a completely tapered choke for the entire course of their production. If the lack of a parallel section caused blown patterns none of these guns would shoot worth a darn.

Your issue just proves the point that every gun or in this case every barrel shoots differently with any given load. If your bore gauge is one of the dial types try rotateing it at several points in your suspect choke. What you may have is a concentricity problem where the end of the barrel has been dinged or dented in the past and now is oblong rather than a nice round circle.

The other thing to consider here is that one of your barrels has a full taper choke and the other has a parallel section to it. This tells me one or the other chokes has been altered at some time. I suspect that the parallel one is the one that has been altered. If this were my gun I would get it to a choke specialist like Mike Orlen, tell them what your experiencing and follow thier recommendations to correct the problem.

Thanks for the info, I had intended on using the reamer from the breech with guide bushings. I am not going to do anything with it until I can talk with someone of Mr. Orlen's knowledge level.

It is good to know that other guns have this tapered choke but like my LC they were built for felt wads not modern plastic shot cups. I can see how a taper would work well for felt since the shot package is not confine to a shot cup.
If either choke has had work done since it left the factory I can't tell. It is possible that it was bored Full n Full when new. I am just going by what I see with the bore gauge (Skeets) one tube has a parallel the other doesn't. The right barrel performs perfectly and is not load sensative. Left barrel performs poorly unless using a real light weight shot charge.
If I can find some old shells that still go bang I'll test them on paper and see how they do.
Thanks again.

Dave, you mention that your left barrel is slightly tighter than full??? How many thou are we talking here. Your poor performance sounds like overchoking. A few decades ago when I was experimenting with buffered lead loads, I was getting 95% plus patterns from 25 thou of choke. Plastic wads and hard shot etc. make a BIG difference.