overbore barrel

publius · February 1, 2013, 01:37 PM

Does anyone besides Mossberg make an auto with the large bore barrel? thanks.

BigD_in_FL · February 1, 2013, 02:03 PM

IIRC, Beretta does, at least on some models

tjh · February 1, 2013, 09:55 PM

Browning says thier barrels are back bored , is that the same thing you talking about .

zippy13 · February 1, 2013, 09:57 PM

IIRC, my R-1100 Trap gun is overbored.

publius · February 2, 2013, 01:19 PM

No, what I'm talking about is the 10 ga. barrel on the Mossy 835/935.

Virginian · February 2, 2013, 03:30 PM

You do not have a 10 gauge barrel on your Mossberg unless you have had some extensive gunsmithing done. Overbore or backbore usually refers to barrels that have an inside diameter larger than the standard for that gauge. There have been, and are, factory examples produced by several manufacturers. Many gunsmiths offer the service. The merits are usually a source of debate. I got slightly increased velocities with some loads, and a marginal increase in pattern efficiency with several barrels I had backbored.
If you get too big, most plastic wads I have seen start running in to sealing issues. If you have too little or the wrong powder, you can lose a little velocity.

B.L.E. · February 3, 2013, 08:51 PM

I would think that if you overbored a 10 gauge barrel, it might technically become illegal for migratory bird hunting, though most game wardens would probably call it a 10 gauge if it shoots 10 gauge shells.

BigJimP · February 4, 2013, 04:16 PM

Why ?? - or what are you trying to do ??

Dreaming100Straight · February 5, 2013, 03:21 AM

I do not know how current this is but per Mossberg

Quote:

* * * 935™ and 835® 12-gauge barrels are overbored to 10-gauge dimensions

and see this:

Quote:

12-GAUGE MUZZLE COMPARISON: (.775) Overbored 12-gauge 835 Ulti-Mag barrel (left) -vs- our standard (.731) 12-gauge barrel (both barrels are shown with flush-fitting choke tubes installed).

Still, I am not sure that is a true 10 gauge bore as I believe a 10 gauge is a .779" bore diameter. but what is .004"?

Virginian · February 5, 2013, 07:06 AM

Yes, the bore diameter is nominally a 10 gauge, but it is an overbored 12 gauge barrel, not a 10 gauge barrel, was my point. Back when I was experimenting I found I couldn't get good wad sealing over about .742". "Wasted" 2 barrels in the process. I was not dealing with 3-1/2". I have not heard any bad reports on the Mossbergs, so I wonder if the manufacturers have modified the wads, or if some wads do better than others.
The early 3-1/2" 12 gauge BPSs were built on the 10 gauge receiver, and a guy who had a 12 borrowed my 10 and said the barrels would swap. I don't know if the gun would have functioned or not. I do know that was a heavy 12 gauge if it did.

February 1, 2013, 01:37 PM	#1
publius Senior Member Join Date: January 25, 2005 Location: Mississippi/Texas Posts: 2,505	overbore barrel Does anyone besides Mossberg make an auto with the large bore barrel? thanks. __________________ "Suppose you were an idiot, and suppose you were a member of Congress, but I repeat myself." Mark Twain

February 2, 2013, 01:19 PM	#5
publius Senior Member Join Date: January 25, 2005 Location: Mississippi/Texas Posts: 2,505	No, what I'm talking about is the 10 ga. barrel on the Mossy 835/935. __________________ "Suppose you were an idiot, and suppose you were a member of Congress, but I repeat myself." Mark Twain

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February 1, 2013, 02:03 PM	#2
BigD_in_FL Junior member Join Date: December 20, 2012 Location: The "Gunshine State" Posts: 1,981	IIRC, Beretta does, at least on some models

February 1, 2013, 09:55 PM	#3
tjh Senior Member Join Date: September 25, 2009 Location: North Central Ohio Posts: 171	Browning says thier barrels are back bored , is that the same thing you talking about .

February 1, 2013, 09:57 PM	#4
zippy13 Senior Member Join Date: August 23, 2008 Location: SoCal Posts: 6,442	IIRC, my R-1100 Trap gun is overbored.

February 2, 2013, 03:30 PM	#6
Virginian Senior Member Join Date: February 11, 2012 Location: Williamsburg, Va. Posts: 1,528	You do not have a 10 gauge barrel on your Mossberg unless you have had some extensive gunsmithing done. Overbore or backbore usually refers to barrels that have an inside diameter larger than the standard for that gauge. There have been, and are, factory examples produced by several manufacturers. Many gunsmiths offer the service. The merits are usually a source of debate. I got slightly increased velocities with some loads, and a marginal increase in pattern efficiency with several barrels I had backbored. If you get too big, most plastic wads I have seen start running in to sealing issues. If you have too little or the wrong powder, you can lose a little velocity.

February 3, 2013, 08:51 PM	#7
B.L.E. Senior Member Join Date: December 20, 2008 Location: Somewhere on the Southern shore of Lake Travis, TX Posts: 2,603	I would think that if you overbored a 10 gauge barrel, it might technically become illegal for migratory bird hunting, though most game wardens would probably call it a 10 gauge if it shoots 10 gauge shells.

February 4, 2013, 04:16 PM	#8
BigJimP Senior Member Join Date: February 23, 2005 Posts: 13,195	Why ?? - or what are you trying to do ??

February 5, 2013, 07:06 AM	#10
Virginian Senior Member Join Date: February 11, 2012 Location: Williamsburg, Va. Posts: 1,528	Yes, the bore diameter is nominally a 10 gauge, but it is an overbored 12 gauge barrel, not a 10 gauge barrel, was my point. Back when I was experimenting I found I couldn't get good wad sealing over about .742". "Wasted" 2 barrels in the process. I was not dealing with 3-1/2". I have not heard any bad reports on the Mossbergs, so I wonder if the manufacturers have modified the wads, or if some wads do better than others. The early 3-1/2" 12 gauge BPSs were built on the 10 gauge receiver, and a guy who had a 12 borrowed my 10 and said the barrels would swap. I don't know if the gun would have functioned or not. I do know that was a heavy 12 gauge if it did.