shotgun choke reaming

yellowknifedave

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Howdy.
I have a number of barrels that I would like to ream to use steel shot in. I would imagine I would like to aim for Improved modified (.704") or modified (.710").

Since we are talking volume, I could probably buy the correct reamer for the price of having just one or two barrels done. I have been looking for a while for a good setup to use, and kind of have one picked out, but I figured I would go to the pros on the board here for advice before I purchase.

What specific tool would you all recommend to ream a more generous choke, and where is it available?

Thanks.

YKD
 
I've done a few of them in the past , what I do is bore them out on the lathe , single point no reamer. Make the hole about .710 for steel shot.
 
SHOTGUN BARREL ALTERATIONS FOR STEEL SHOT

Forcing Cone Alteration:

Factory shotgun barrels usually have a fairly short and abrupt forcing cone. The forcing cone is the tapered area just ahead of the chamber where the shell is contained. Altering the forcing cone, so it is one and one half or two inches in length, reduces recoil and improves the pattern density. Trap shooters and skeet shooters have been doing this for many years. It is a good benefit to the steel shot user as well.

Choke Alteration:
Choke designation from the tightest to the most open are:
Extra Full, Full, Improved Modified, Modified, Skeet II, Improved Cylinder, Skeet I, and Cylinder Bore.

Steel shot does not require the constriction that lead shot needs, to produce good patterns. In fact too much constriction, causes poor, erratic patterns
, and in some cases, permanently damages the barrel. I have seen barrels bulged at the choke, I have seen barrels where the choke split right open, from using steel shot.

For steel shot, with thin barrels, chokes should be altered to at least Skeet II. Often, over & under, and side-by-side shotguns, are best altered to Skeet I and Skeet II chokes. Heavier barrels can be left at Modified choke but may see an improvement in the pattern if opened slightly.


You can buy an expandable reamer and if you hold the reamer in a lathe and center the barrel on the tail stock center, it works fine at low rpm, a little at a time.
 
I have done a few hundred barrels in my shop. You first have a few thinge to look at. First off you need to know what barrel diameter you have in you barrel.
Second you need to know if the barrel is chrome lined or just polished metal.
 
Thanks for all of the info so far, I appreciate it. Most are double guns, and combos, so I canot use the lathe. I have adjustable reamers for other applications that I may use, but I have to come up with some sort of extension to feed them from the chamber (guntech youtube video from MIDWAY USA recommends that way.

Most are doubles, and quite thin walled, and not chrome lined. I will look at opening them to Skeet 1 or 2....

Any recommended reamer anyone knows of, that is capable of having an extension added?

Thanks again.

Dave
 
You can do any type of barrel, double, O/U or single. You need a mill attachment on your lathe to hold the barrels. As for what type of reamer you need, it all depends on the bore size of the barrel and the amount of opening you are trying to achieve. I use Clymer reamers ( carbide) for most of my tooling. This type of operation has to be done from the breech to the muzzel. There is no other way to do it properly.
You must have a reamer extention attachment ,manderal and breech center guide for the reamer extention.
If you have any more questions I would be happy to answer them for you.
 
You can do any type of barrel, double, O/U or single. You need a mill attachment on your lathe to hold the barrels. As for what type of reamer you need, it all depends on the bore size of the barrel and the amount of opening you are trying to achieve. I use Clymer reamers ( carbide) for most of my tooling. This type of operation has to be done from the breech to the muzzel. There is no other way to do it properly.
You must have a reamer extention attachment ,manderal and breech center guide for the reamer extention.
If you have any more questions I would be happy to answer them for you.

I have been doing them properly from the muzzle in the lathe for 30 years... I would not do them by hand from the muzzle though. That requires through the breech in my opinion.
 
Howdy again.
I have found interesting information in my search for tools. The best reference I have found for choke diameters indicates:
True bore diameter - .729
Cylinder -.729
Skeet 1 - .724
Improved cylinder - .720
Skeet 2 -.717
Modified - .710
Improved Modified - .704
Full - .694
Extra full - .689

I have checked a few of my full choked shotties with a digital caliper, and they correspond pretty close to the figure given

Clymer sells choke reamers in the following diameters:


12 Gauge .720 .725 .730 .735 .740

I am interested in opening my chokes to modified and skeet 2 (mostly to shoot steel shot). Which reamers would I need?

Thanks again for all of the help.

Dave
 
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