Back bored shotguns
- Thread starter warzaw
- Start date
Falconflyer
CGN Ultra frequent flyer
Back bored refers to a gun that has had the barrel bored to a larger diameter, over bore refers to a gun that has been manufactured with a bore larger than what is perceived as the nominal/traditional bore diameter for that gauge. The two terminologies are bandied about willey nilley by both shooters and manufacturers alike.
Overboring a shotgun barrel is arguably better depending on who your talking to. Better patterns... yeah maybe... lower recoil... yeah maybe... sales hype... yeah probably.
.729 inches or 18.5mm would be considered standard bore diameter for the 12 gauge. Beretta settled on .733 for their so called "over bored" barrels while Browning selected .742 as the "ideal" diameter. One reason why neither went bigger was that the larger diameters don't do well to seal fiber wads like they do plastic wads, the UK and EU use a lots of fiber wads!
There's lots of interesting reading out there in the world wide net so you should do some research and make you own decisions!
Overboring a shotgun barrel is arguably better depending on who your talking to. Better patterns... yeah maybe... lower recoil... yeah maybe... sales hype... yeah probably.
.729 inches or 18.5mm would be considered standard bore diameter for the 12 gauge. Beretta settled on .733 for their so called "over bored" barrels while Browning selected .742 as the "ideal" diameter. One reason why neither went bigger was that the larger diameters don't do well to seal fiber wads like they do plastic wads, the UK and EU use a lots of fiber wads!
There's lots of interesting reading out there in the world wide net so you should do some research and make you own decisions!
1963beretta
CGN Ultra frequent flyer
- Location
- Vaughan, Ontario
The Mossberg 935 is over bored to 10g dimensions. Mine patterns better than any of the other shotguns I currently own and have owned. Call it a gimmick, call it hype….call it what you want. The only thing that matters to me is how it shoots. And I have not patterned a gun that does it better.
Patterns are great for stationary targets, but when shooting at a flying targets, shot string is equally important. There is another thread about shot string that explains what it is. Now I cant say I’ve ever measure shot string, but if the theory is true that shot string is reduced with a larger bore, then that would appeal to me with regards to over bored barrels.
Patterns are great for stationary targets, but when shooting at a flying targets, shot string is equally important. There is another thread about shot string that explains what it is. Now I cant say I’ve ever measure shot string, but if the theory is true that shot string is reduced with a larger bore, then that would appeal to me with regards to over bored barrels.
Falconflyer
CGN Ultra frequent flyer
I've read about experiments where they bore a 12 gauge out to .775 and they found it patterned very well but they had trouble finding shells who's wad's would seal consistently. That was a long time ago and maybe we have better wads for over bored barrels now.
As with most things in the firearms world, the oversized bore was conceptualized and thoroughly explored long ago. At least as far back as the 1880’s the British were using guns with 12 gauge chambers and 10 gauge bores, mostly for competition pigeon shooting, the early form of trap shooting. They were referred to as ‘chamberless’ guns. Because the felt or fibre wads of this time provided little bore filling expansion, normal 12 gauge wads from paper cases resulted in excessive blow by so the solution was to use very thin walled brass cases with larger 11 or 10 gauge wads. I’ve had a couple of these guns and they cause a lot of confusion because when looking down the barrel from the breech end there is usually no noticeable step ( leade, forcing cone) visible, it looks like one continuously bored tube, with possibly a hint of a chamber. This shows up on the proof marks, the bores being marked as ‘10’ or ‘9’ but the 12 gauge chambers won’t accept a 10 gauge shell. Also if a chamber Diamond mark is present it will contain a 12. These old guns can throw some beautiful patterns with our modern thin 12 gauge plastic hulls and suitable modern expanding plastic shotcup wads using appropriate loads.
You have not patterned a 10ga then. I own both and the 10ga hands down over a back bored 12ga any day of the week
Mac I have to back Beretta on the 935 post I have owned one since they first came out. That model with 2 1/4 of shot will run with my SP 10 all day long.and I love my SP10. My SX 2 3 1/2 " guns with their back bores are a waste of time as is my 11-87 trap gun total garbage. My 935 is the only back bored 12 gauge gun that works for me . It kills turkeys and geese with ease right along side of my SP10.
Don't own a 935 but own lots of 3 1/2 of most other makes and all fall short of a 10ga on paper starting with the old mossy 835 when it came out OUCH my shoulder hurts thinking about it
1963beretta
CGN Ultra frequent flyer
- Location
- Vaughan, Ontario
I was referring to 12g shotguns as that was what the OP was speaking about. Admittedly, I have not yet patterned my 10g Browning, but I wouldnt doubt that it patterns better
But the Mossberg 935/835 with 10g bores throw a hell of a pattern for a 12g gun.
I don't worry too much about this stupid shot gun thing, in court never stand up ,But I am side tracked.
I had one , a 2 barrel Hi end Spanish skeet gun. I pattered those barrel a couple 3 times, I have never seen as nice a pattern than that back bored barrel shot.
But I have not played with a large number of Hi end guns like a few here.
Understand but know 100% the 835 doesn't match the 10ga tried and owned that MULE
The heavy payload in the 935 along with the larger bore works well with smaller #4 #6 plated lead shot but when it comes to steel bb and triple b and up the 10 takes over. think we would agree with that Mac . know you have loaded a ton of steel.
I only patterned them with steel and never smaller than BB and of course the special duplex loads of steel BBB over BB and TT over BBB
Plated lead shot is for the 16 ga
Cheers
Nothing will outshoot a 10. Theyre a beast of their own. I guided for a living and used a BPS 10 to kill cripples from the lead days to the steel days. A LONG TIME. My gun was nicknamed BLACK DEATH. A poor shot will never notice the advantage but a skilled shooter will cleanly harvest birds at very long range. With the intro of the 3 1/2 12 gauge, the overbored or backbored barrels came into the limelight. Better than standard but still not close to the mighty ten. The BLACK DEATH was because of the synthetic stock and matte blue finish, along with taking very few prisoners!
1963beretta
CGN Ultra frequent flyer
- Location
- Vaughan, Ontario
Funny you mention that. My Mossberg 935 didn’t like the original Black cloud shells. When Federal came out with the new flitecontrol wads, they were like a totally different ammunition. I really like the new Black Cloud shell. Definitely my favourite waterfowl ammo
Falconflyer
CGN Ultra frequent flyer
My memory of the article is vague but it may have even been Browning doing that particular experiment and the reason why they backed down to .742 as their standard bore.
Agree 100%. They boys named mine which was also black like yours the executioner and back in the lead days those federal 2 1/4 oz buffered BB plated loads would kill stone dead past 75 yards and not fluke but every time if I was on
Take care
I agree with the bps 10ga ruling with bigger shot. I also agree that Mossberg got the 935 right as they do pattern well with bigger heavier loads even slightly better than my a400. The Beretta does better with smaller shot and lighter loads
A side note on black cloud in 10ga. Maybe I have defective loads but it is the tightest shooting shell I've ever fired. The shot cup just doesn't pull away. At 25 yards it's like a slug. Great for long shots and water swatting. The new flex wad makes the black cloud perform like it's intended. Spread out to help those who basically missed. I prefer a dense pattern as my misses are in front or behind rarely over or under so sending pellets out in those directions seems like a waste to me
I haven't found an exact coupling of guns where one is over bored and one isn't to compare recoil feel but if constricting the choke can increase recoil feel I'd like to believe a bigger bore would reduce recoil
A side note on black cloud in 10ga. Maybe I have defective loads but it is the tightest shooting shell I've ever fired. The shot cup just doesn't pull away. At 25 yards it's like a slug. Great for long shots and water swatting. The new flex wad makes the black cloud perform like it's intended. Spread out to help those who basically missed. I prefer a dense pattern as my misses are in front or behind rarely over or under so sending pellets out in those directions seems like a waste to me
I haven't found an exact coupling of guns where one is over bored and one isn't to compare recoil feel but if constricting the choke can increase recoil feel I'd like to believe a bigger bore would reduce recoil
