Dave McCracken
Moderator In Memoriam
Back in the 1800s and possibly earlier, folks found their shotguns often shot better after some use. With the corrosive percussion caps and primers of the day combining with the residue left by black powder,oft bores had to be "Freshened" by honing out a few thousandths. Thus bores oft became somewhat larger than nominal. The .729" that 12 gauge bores are supposed to be oft became .735 or .740 afterwards.
Old time barrel mavens like Dan Lefevre and Burt Becker tried this on such shotguns as the 10 gauge Super Fox and the earliest 12 gauge 3" Maggie Numbs. Results were sometimes phenomenal and sometimes not.
Definitions:
Overbored is a barrel made larger from scratch. Backboring is enlarging a barrel already made.
And then the 60s saw the introduction of the plastic wad, and it was a whole new game. The plastic wad ensured obturation in the bore and could accomodate a larger Inside Diameter without leaking gas and blowing the pattern. And, the protection of the cup meant more pellets in a load stayed round, and thus stayed in the pattern.
In the 70s, Brister and Stan Baker teamed up to try out backbored barrels by enlarging an 1100 barrel and patterning before and after. The results were good, and Baker went on to make lots of overbore barrels before his recent death. A Baker Big Bore barrel can go to .800" ID and sell for thousands of dollars.
I shot trap last year with a man who had a set of Baker barrels made for his Model 32 Remington. Some decent running used cars cost less.He was quite happy with the barrels and seemed to shoot well.
There's a fair number of good smiths and companies like Briley and Vang out there that will happily hone out barrels and install choke tubes to match.
Backboring can add choke to a barrel with little or none if one hones out to a point an inch or two behind the muzzle and leaves the original diameter intact there.
It can also take some weight out of the barrels and turn what feels like a railroad tie into something more responsive.
It also eases kick a trifle, though I'm unconvinced most people can feel the difference.
And it can improve patterns, though this is by no means a given.To fudge it further,it depends on what is meant by "Improved". Often, I'm told, overbored barrels used with the same amount of relative constriction keep up center density further out and more pellets in the fringes of the patterns.
Two large groups tend to favor overbores. The first are those using heavy loads, like nontoxic waterfowl, buck and turkey loads and want ultimate performance and minimum kick. These folks work with large shot, heavy charges, and often regard an overbore the same way hot rodders used to regard a small block 350 punched out to 427 cubic inches. One common shotgun used here is the Mossie 835, which has an overbored barrel from the factory and 3.5" capacity. I'm still unconvinced of the need for 3.5" loads, but the 835 can be used with the shorter ones and is lots of gun for the money. Here not many shells are shot at one time, but the loads are heavy and the pellets large.
The second group are target shooters. My acquaintance with the 32 Remington is an example. Folks want the overbores for less kick, better patterns,and a little less weight in the longer barrels long favored by trap shooters and those SC folks going to 30" and 32" O/Us for a smoother swing. Here they're shooting lighter loads with smaller shot and lots of them.
Both groups like overbores. My hunch is the first group benefits more.
The downside....
Besides the expense, many barrels are bored non concentrically, and overboring can leave too little metal to contain the pressure. Removing some of the metal between us and 13K PSI of hot gases may not be the brightest idea since the light bulb even in a good but not overbuilt barrel. The Remington Light Contour barrels are not good candidates for backboring. OTOH,one of the standard barrels from Remington could be.
And, some excess is certainly wretched. Extreme overbores have a reputation for not obturating in colder weather. Funny sounding loads, poor performance, and the odd wad left in the barrel to create a hazard are reported. .745" may be the limit on this, but YMMV.
How necessary is it? Not at all. Some folks will shoot a bit better with a shotgun a few oz lighter in front. Some will find their long range patterns a bit denser.
Remember our definition. Something that is useful in directing that cloud or clouds of shot to the target at the right time and in comfort is of worth.
And for comparison, though your results will vary....
The barrel on the TB goes .733", a mild overbore and has 38 POC.
The barrel on #6, made in 1955 goes .725", and has 40 POC.
The new LC barrel goes .7285", has 39 POC with the Full choke tube supplied by HSmith, and has a longer forcing cone than the older barrels.
And shooting at the pattern sheets at 30 yards using identical loads and counting ONLY the flyers OUTSIDE the pattern shows them keeping pellets in that same order.
The TB barrel has the fewest flyers, then that tight old 1955 barrel, then the new LC with its better cone.Go figure...
Old time barrel mavens like Dan Lefevre and Burt Becker tried this on such shotguns as the 10 gauge Super Fox and the earliest 12 gauge 3" Maggie Numbs. Results were sometimes phenomenal and sometimes not.
Definitions:
Overbored is a barrel made larger from scratch. Backboring is enlarging a barrel already made.
And then the 60s saw the introduction of the plastic wad, and it was a whole new game. The plastic wad ensured obturation in the bore and could accomodate a larger Inside Diameter without leaking gas and blowing the pattern. And, the protection of the cup meant more pellets in a load stayed round, and thus stayed in the pattern.
In the 70s, Brister and Stan Baker teamed up to try out backbored barrels by enlarging an 1100 barrel and patterning before and after. The results were good, and Baker went on to make lots of overbore barrels before his recent death. A Baker Big Bore barrel can go to .800" ID and sell for thousands of dollars.
I shot trap last year with a man who had a set of Baker barrels made for his Model 32 Remington. Some decent running used cars cost less.He was quite happy with the barrels and seemed to shoot well.
There's a fair number of good smiths and companies like Briley and Vang out there that will happily hone out barrels and install choke tubes to match.
Backboring can add choke to a barrel with little or none if one hones out to a point an inch or two behind the muzzle and leaves the original diameter intact there.
It can also take some weight out of the barrels and turn what feels like a railroad tie into something more responsive.
It also eases kick a trifle, though I'm unconvinced most people can feel the difference.
And it can improve patterns, though this is by no means a given.To fudge it further,it depends on what is meant by "Improved". Often, I'm told, overbored barrels used with the same amount of relative constriction keep up center density further out and more pellets in the fringes of the patterns.
Two large groups tend to favor overbores. The first are those using heavy loads, like nontoxic waterfowl, buck and turkey loads and want ultimate performance and minimum kick. These folks work with large shot, heavy charges, and often regard an overbore the same way hot rodders used to regard a small block 350 punched out to 427 cubic inches. One common shotgun used here is the Mossie 835, which has an overbored barrel from the factory and 3.5" capacity. I'm still unconvinced of the need for 3.5" loads, but the 835 can be used with the shorter ones and is lots of gun for the money. Here not many shells are shot at one time, but the loads are heavy and the pellets large.
The second group are target shooters. My acquaintance with the 32 Remington is an example. Folks want the overbores for less kick, better patterns,and a little less weight in the longer barrels long favored by trap shooters and those SC folks going to 30" and 32" O/Us for a smoother swing. Here they're shooting lighter loads with smaller shot and lots of them.
Both groups like overbores. My hunch is the first group benefits more.
The downside....
Besides the expense, many barrels are bored non concentrically, and overboring can leave too little metal to contain the pressure. Removing some of the metal between us and 13K PSI of hot gases may not be the brightest idea since the light bulb even in a good but not overbuilt barrel. The Remington Light Contour barrels are not good candidates for backboring. OTOH,one of the standard barrels from Remington could be.
And, some excess is certainly wretched. Extreme overbores have a reputation for not obturating in colder weather. Funny sounding loads, poor performance, and the odd wad left in the barrel to create a hazard are reported. .745" may be the limit on this, but YMMV.
How necessary is it? Not at all. Some folks will shoot a bit better with a shotgun a few oz lighter in front. Some will find their long range patterns a bit denser.
Remember our definition. Something that is useful in directing that cloud or clouds of shot to the target at the right time and in comfort is of worth.
And for comparison, though your results will vary....
The barrel on the TB goes .733", a mild overbore and has 38 POC.
The barrel on #6, made in 1955 goes .725", and has 40 POC.
The new LC barrel goes .7285", has 39 POC with the Full choke tube supplied by HSmith, and has a longer forcing cone than the older barrels.
And shooting at the pattern sheets at 30 yards using identical loads and counting ONLY the flyers OUTSIDE the pattern shows them keeping pellets in that same order.
The TB barrel has the fewest flyers, then that tight old 1955 barrel, then the new LC with its better cone.Go figure...
