Shotgun Bore Burnishing:
Actual gains in pattern density, evenness and point of impact consistency can be had cheaply by simply burnishing the shotguns bore, chamber and forcing cone. This applies to all shotgun bores other than chromed bores, all shotgun bores are polished but not burnished, burnishing removes all the scratches from shotgun bores left by polishing with abrasives.
This is very consistent and your first line of defense in greatly reducing moisture trapped in the bore of the shotgun which then starts the process of rust formation in the barrel.
Shotgun bore burnishing actually closes the pores in the gun metal and leaves the metal surface very slick, it will make almost any shotgun more consistent in patterning and point of impact.
Shotgun bore burnishing reduces substantially plastic fouling left in shotgun bores from plastic wads, which in turn reduces pattern consistency.
Burnishing is really simple to do, but, it is very time consuming, when done properly, it can be very rewarding in benefit of increased pattern density and consistency.
To Burnish A Shotgun Bore All You Need Is:
1. A 3/8″ or larger dowel rod the length of the shotgun barrel.
2. An electric drill.
3. 0000 steel wool.
Note: Steel wool coarser than 000 may actually scratch the bore.
How To Burnish:
1. Take the dowel rod and make a few nicks in the end that you will run through the bore just enough to grab the steel wool.
2. Wind the steel wool around the dowel rod like a q-tip just enough so that it will pass through the bore of barrel while being spun by the drill.
3. Next just chuck the rod in the drill and start burnishing.
4. Run the whole rod back and forth the entire bore for about an hour.
Note: The barrel will heat up during this process, so, care should be taken here.
Tip: If the shotguns bore is rough from rust, a little shot of wd-40 on the steel wool will help in removing it.
Result: I have used this method on all my shotguns and results are always the same, extremely bright bores and consistent shooters.
Shotgun Barrel Back Boring
Shotgun barrel back-boring is nothing more than the machining process of reaming or boring a shotgun barrel to a larger interior diameter.
This is usually done by a very knowledgeable gunsmith in the efforts to save a rusted shotgun barrel and usually is done as a few thousandths of an inch clean up pass through the barrel.
The barrel is then usually polished and burnished inside, restoring the barrels interior back to a usable state of condition do to boring. A back-bored shotgun barrel simply means that the bore has been altered to a larger inside diameter.
Back-boring of any particular gauge, does; beyond any doubt, add to more wider center mass and will help reduce the length of shot strings in shotguns and when done within reason it does not decrease the velocity of the shotshell load.
The reason that it does not decrease the velocity is, today’s plastic wads will expand a great deal to seal the bore of the shotgun and not allow gas to escape around the wad. No gas leak, no velocity lost.
As you open up the bore of a shotgun it takes less choke constriction to still get the same pattern as one with a standard bore. This is a big bonus to all that love to shoot trap and other sporting clay games because this puts more pellets into the center mass of the shot-string and over-all shortens the shot string reducing the time frame from first pellet strike to the last.
Choke constriction is measured in thousands of an inch plus or minus from the bore diameter to a designated choke size such as 12 gauge bore .729 full choke= .035″ constriction, modified choke – .019″ constriction or improved cylinder choke = .009″ constriction. Open up the bore then you open up the choke for the same choke result on a fixed choke shotgun.
If you do decide to do this. Make sure you send your barrel to someone that is experienced with this procedure and their level of finish work is excellent. This is by no means an easy process to get right. See diagram below for other issues to consider.