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Posted: 9/14/2010 12:31:05 PM EDT
Posted this in the S.G. forum but it didnt get any circulation and Im curious about this.

I was reading a mossberg catolog about this. I cant see the advantage of firing a 12 gauge diameter charge down a 10 gauge bore diameter. Apparently the gasses "surround and cushion" the shot charge for more uniform petterns according to the written explanation. Wouldnt this cause the propellant gasses to blow by the shot cup? Wouldnt this reduce velocity and cause the charge and wad to bounce too and fro along the barrel wall since its smaller than the bore diameter, much like an undersize musket ball?
Im pretty up on internal and external ballistics, and I cant see this working as advertised. Then again, aeronautically speaking (my line of work) a bumblebee should never be able to fly either, so wierder concepts have worked.
What say you guys? Any input is appreciated, and thanks in advance
Link Posted: 9/14/2010 12:41:23 PM EDT
IBK_J
Link Posted: 9/14/2010 12:44:34 PM EDT
That makes no sense at all to me. Are you sure the term isn't backbored ?
Link Posted: 9/14/2010 12:46:14 PM EDT
Originally Posted By mark75101:
IBK_J


Is he even still alive?

Haven't heard a peep from him in like 2 weeks.
Link Posted: 9/14/2010 12:47:32 PM EDT
I've not seen the particular barrels you are talking about, but I do know that there are chokes that use the same principle.

They are called jug chokes where the bore is opened up for a distance along the length and then closes back down. It's supposed to let the shot column "relax" and therefore fly truer/tighter pattern.

Don't know how well it works. A lot of firearm gimmics might make a miniscule difference and people like to spend their money. Look at golfers who spend thousands on a set of clubs that the average golfer will never notice the difference. How about fishermen who spend money on a boat that goes 60 mph. Do you really have to chase the fish down, or what?
Link Posted: 9/14/2010 12:49:10 PM EDT
Its fully overbored, described as using a 10 gauge barrel blank chambered for 12 gauge. I know all about backboring the forcing cone but this just seems a little silly from an engineering standpoint.
Link Posted: 9/14/2010 12:54:14 PM EDT
It's also said to reduce recoil in heavy magnum loads-which is why 3 1/2 inch chambered 835s are backbired/overbored and 3 inch 500s aren't. I've never noticed much difference, there's really no escaping the pain if you use 3 1/2 inch magnums.
Link Posted: 9/14/2010 12:55:57 PM EDT
Never heard of it, but it makes sense, and dosent at the same time.

Anyone else think that?

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Link Posted: 9/14/2010 12:56:34 PM EDT
Originally Posted By shack357:
It's also said to reduce recoil in heavy magnum loads-which is why 3 1/2 inch chambered 835s are backbired/overbored and 3 inch 500s aren't. I've never noticed much difference, there's really no escaping the pain if you use 3 1/2 inch magnums.


This is what I have been told. Recoil reduction. I've also been told it is a myth.
Link Posted: 9/14/2010 12:57:45 PM EDT
Originally Posted By dedfella:
Originally Posted By shack357:
It's also said to reduce recoil in heavy magnum loads-which is why 3 1/2 inch chambered 835s are backbired/overbored and 3 inch 500s aren't. I've never noticed much difference, there's really no escaping the pain if you use 3 1/2 inch magnums.


This is what I have been told. Recoil reduction. I've also been told it is a myth.


If it reduces recoil be letting more gas escape around the edges of the wad then it sounds pretty pointless... you could accomplish the same thing by just using less powder, couldn't you?
Link Posted: 9/14/2010 12:58:56 PM EDT
From the catalog :

"In addition, all 835® Ulti-Mag® smooth bore barrels are overbored to 10 gauge bore dimensions, reducing recoil and producing exceptionally uniform patterns from both light and heavy shot charges. Working in tandem with the performance-enhancing overbored barrels, strategic placement of eight ports on each side of the 835® barrel direct gasses upward and outward to not only reduce felt recoil, but to minimize muzzle jump for quick second shot recovery."

Sounds like a gimmick to me.
Link Posted: 9/14/2010 1:01:11 PM EDT
Never heard of it. Are you sure the ENTIRE barrel is cut to 10 ga diameter? It's just not back-bored?

Does this have something to do with those ridiculous muzzle attachments Mossberg is using these days?
Link Posted: 9/14/2010 1:01:48 PM EDT
Originally Posted By 1Andy2:
Originally Posted By dedfella:
Originally Posted By shack357:
It's also said to reduce recoil in heavy magnum loads-which is why 3 1/2 inch chambered 835s are backbired/overbored and 3 inch 500s aren't. I've never noticed much difference, there's really no escaping the pain if you use 3 1/2 inch magnums.


This is what I have been told. Recoil reduction. I've also been told it is a myth.


If it reduces recoil be letting more gas escape around the edges of the wad then it sounds pretty pointless... you could accomplish the same thing by just using less powder, couldn't you?


ding-ding

My understanding of physics is limited so someone else can weigh in and point out where that theory is wrong I suppose

Had a guy who bird hunted with us last year try and explain it but all I could think of was Nigel saying "This one goes to 11"
Link Posted: 9/14/2010 1:02:30 PM EDT

Originally Posted By 583:
From the catalog :

"In addition, all 835® Ulti-Mag® smooth bore barrels are overbored to 10 gauge bore dimensions, reducing recoil and producing exceptionally uniform patterns from both light and heavy shot charges. Working in tandem with the performance-enhancing overbored barrels, strategic placement of eight ports on each side of the 835® barrel direct gasses upward and outward to not only reduce felt recoil, but to minimize muzzle jump for quick second shot recovery."

Sounds like a gimmick to me.

"Hey, Larry ... Remember when you had me order those new barrels for the 835s?"

"Yeah."

"Did you say '10 gauge' or '12 gauge?'"

"12"

"..."

"Why?"

"Oh, never mind. Hey, I'm gonna run over to the marketing department for a minute."
Link Posted: 9/14/2010 1:10:32 PM EDT
I think the whole idea is to obtain more consistent patterns. I first saw them at turkey shoots. It got to be the winners weren't the best shot, but who had the best machinist...
Link Posted: 9/14/2010 2:18:03 PM EDT
[Last Edit: 9/14/2010 2:18:23 PM EDT by odiedodi]

Originally Posted By 1Andy2:
Originally Posted By mark75101:
IBK_J


Is he even still alive?

Haven't heard a peep from him in like 2 weeks.
He probably got banned for knowing too much...

Link Posted: 9/14/2010 6:58:12 PM EDT
Originally Posted By dedfella:
Originally Posted By shack357:
It's also said to reduce recoil in heavy magnum loads-which is why 3 1/2 inch chambered 835s are backbired/overbored and 3 inch 500s aren't. I've never noticed much difference, there's really no escaping the pain if you use 3 1/2 inch magnums.


This is what I have been told. Recoil reduction. I've also been told it is a myth.


Based on my experience comparing the two, it's either a myth or the reduction is miniscule. I had a 3 1/2 inch 870, my cousin had a ported and overbored 835. I fired ammo from the same box of 3 1/2 inch goose loads in both guns, he did the same. Neither of us felt a noticeable difference.

Link Posted: 9/14/2010 10:22:47 PM EDT
I don't notice any difference in recoil, but I enjoy recoil. Friends who hunt near me in a duck blind say that my 835 is too loud though.
Out in the dove fields nobody ever complained;



When I first got it I had some confusion about the choke tubes, and ended up shooting steel shot through a NWTF extra-full lead-only choke. I've been told that the overbore is what kept it from blowing up, though I don't know that to be true.
Link Posted: 9/15/2010 3:58:40 PM EDT
Originally Posted By GoGop:
I've been told that the overbore is what kept it from blowing up, though I don't know that to be true.


Overbore may have reduced pressure enough to avoid ruining the choke tube, but it's not what kept the gun from blowing up. Before I knew any better I fired a heavy steel load through a lead only choke(don't remember which one). All I did was crack the tube and make it a bitch to take out and replace.
Link Posted: 9/15/2010 4:28:45 PM EDT
That's certainly better than a face full of shrapnel. :eek:
Link Posted: 9/15/2010 4:32:51 PM EDT
Originally Posted By Ridgerunner9876:
I've not seen the particular barrels you are talking about, but I do know that there are chokes that use the same principle.

They are called jug chokes where the bore is opened up for a distance along the length and then closes back down. It's supposed to let the shot column "relax" and therefore fly truer/tighter pattern.

Don't know how well it works. A lot of firearm gimmics might make a miniscule difference and people like to spend their money. Look at golfers who spend thousands on a set of clubs that the average golfer will never notice the difference. How about fishermen who spend money on a boat that goes 60 mph. Do you really have to chase the fish down, or what?


No but you do have to hit as many holes as you can before the tournament is over, and beat other fisherman too it. That being said about fishing, I'd be curious to see what similar shotshells would should out of a conventional 12ga barrel, and traditional 10ga barrel and a 20ga barrel. I lover the 12ga, but I'm not convinced that it is the most accurate of the gauges.
Link Posted: 9/15/2010 4:46:11 PM EDT
I don't know but I have an 835 Ulti-Mag in 3.5" that's overbored and has a ported barrel, it is a turkey slaughtering machine. I've killed two doubles at 35 and 40 yards shooting 2 3/4 and 3" winchester supreme #4's.

If you want a turkey gun teh price and featrues really cant be beat.

HOWEVER.

The barrel is not chrome lined as far as I can tell and you need to clean it immediately when you get home if you've shot it.
Link Posted: 9/15/2010 4:59:35 PM EDT
They say it increases velocity. It doesn't.

They say it decreases recoil. It doesn't.

They say it can improve patterns. It can, but it's one of those "all other things being equal" caveats.

The base of most plastic shotgun wads obturate during the setback phase of propellant ignition. It expands to fill the larger diameter bore as the rapidly expanding gasses act upon it.
Link Posted: 9/15/2010 5:03:14 PM EDT
Originally Posted By SevenMaryThree:
They say it increases velocity. It doesn't.

They say it decreases recoil. It doesn't.

They say it can improve patterns. It can, but it's one of those "all other things being equal" caveats.

The base of most plastic shotgun wads obturate during the setback phase of propellant ignition. It expands to fill the larger diameter bore as the rapidly expanding gasses act upon it.


Well I guess it's a gimmick then.
Link Posted: 9/15/2010 5:04:37 PM EDT
Originally Posted By 1Andy2:
Originally Posted By mark75101:
IBK_J


Is he even still alive?

Haven't heard a peep from him in like 2 weeks.


He probably built a time machine or something.
Link Posted: 9/15/2010 5:15:35 PM EDT
[Last Edit: 9/15/2010 5:17:38 PM EDT by SevenMaryThree]

Originally Posted By 583:
Originally Posted By SevenMaryThree:
They say it increases velocity. It doesn't.

They say it decreases recoil. It doesn't.

They say it can improve patterns. It can, but it's one of those "all other things being equal" caveats.

The base of most plastic shotgun wads obturate during the setback phase of propellant ignition. It expands to fill the larger diameter bore as the rapidly expanding gasses act upon it.


Well I guess it's a gimmick then.

Oh I dunno...I think when used in conjunction with elongating the forcing cones and using elongated chokes, it can result in significant pattern improvement.

The real difference you can feel is in the weight removal. By nature, a shotgun is to be used dynamically and balance & weight distribution are critical. By removing .004" from the wall of the barrel, you can really change the personality and handling characteristics of a gun. (I'm talking about $target$ guns here...not Mossbergs or other price point guns.)


Link Posted: 9/15/2010 6:29:35 PM EDT

Originally Posted By navvet89:

The barrel is not chrome lined as far as I can tell and you need to clean it immediately when you get home if you've shot it.

Mine gets cleaned once or twice per year; with a few random sprays of Rem-Oil on the action at various times in between. (Primarily after rainy/snowy duck hunts).
Link Posted: 9/15/2010 6:52:41 PM EDT
they started this years ago in trap guns, where the recoil of shooting 500 rounds in an afternoon it is important. In a hunting gun, it is a waste of time, although there may be a small pattern improvement it was designed as a recoil reducer. I had it done custom along with porting the barrels on mine 35 years ago.
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