View Full Version : Mossberg overbored barrel...

January 25, 2001, 05:29 PM
I have a 12ga. Mossberg 835 Ultimag. It`s indicated that it has an "overbored barrel", is this good or bad? Also, do any other companies offer such a beast?

January 25, 2001, 10:45 PM
It is my understanding that the 835's barrel is 10ga, although it's chambered for 12ga. Notice how your 12ga barrel brush seems to do a crappy job of cleaning the bore? Never can get the bore quite squeaky clean? It's 'cause you need to use a 10ga brush. They don't tell you that in the manual.

Advantages? I'm no shotgun expert, so I regurgitate from memory what I've read about the subject:

The overbored barrel apperently results in tighter shot pattern for a given range when compared to a standard 12ga barrel. Why? I don't know.

January 26, 2001, 12:46 AM
Yes, I did notice that a 12 ga. brush was a little loose and, while you mentioned cleaning I can`t seem to get the barrel clean. I do have a 10ga. brush and brushed the crap out of the barrel and the patches still come out black (dozens of patches). This gun is parkerized (black). I wonder if the inside of the barrel is also parkerized and I`m taking that out when cleaning. When I look down the barrel it never really looks "squeeky clean". I wonder if this stuff will ever come out and if I`m hurting it? Anybody else ever had this problem?

It does seem to hold a pretty tight pattern. I noticed with some 00 buck I was playing with I was getting a 1 foot pattern at 30-40 feet with i/c tube in place.

Dave McC
January 26, 2001, 07:28 AM
Overboring started with the clay gamers,tho Nash Buckingham was doing some research on long range waterfowling in the 40s and 50s and used a Fox double with lengthened forcing cones and nigh 11 ga bbls.

The premise is that with less shot hitting the bore, there's less distortion and the shot fly true, staying in the pattern. Oft those pellets we see on the edge on the pattern are leaving it. Over boring(sometimes called back boring) and longer forcing cones both aid this.

Many smiths refuse to overbore bbls, removing bbl steel isn't a step in the right direction.

Downside, slug groups usually bite from overbored bbls, I understand.

FYI, my chokeless HD 870 patterns 00 into 3-5" at 10 yards, for comparison. No overbore, but a cone job.

January 26, 2001, 08:49 AM
It is not a wise idea to backbore a standard barrel as there won't be much steel left. In contrast the 835 and Browning Gold are both factory overbored/backbored so they start with a barrel with a greater wall thickness. The Beretta 390/391 get a lot of there lightness from thin barrels. If you were to set a 12 ga. 835 or Gold next to a 391 you would think the 391 was a 20 ga. I did this the other day since I have both a 835 and a Gold. You can go to the Mossberg site http://www.mossberg.com/ or the Browning site http://www.browning.com/homepage/homepage.htm and in their descriptions of shotguns they both give good explanations of the over/back boring process.