How realistic is striking 2-4 oz's off a set of barrels? I have no idea (because I've never done it) is that a 4 hour job, an 8 hour job, or longer? Not talking taking the barrels apart, striking the barrels and then relaying the ribs. Just striking the top/side/bottom (I guess). Figure some of those on this forum have certainly done it to remove deep pits, reduce barrel weight etc. Thanks and Happy 4th.

I am doing something related to this right now.
The honest answer to your query is, "I don't know", unless you take alot of measurements, and then figure out the volume of material that your barrels can safely have removed.
That's the honest true answer.
Whether someone else accomplished this, unless you have their barrel measurements to compare to yours, is not safely reliable.
Safety first in all shotgun things.

I am re-profiling a set of Ithaca Flues 32" FxF barrels to the approximate profile of a pigeon gun from 1920.
The maximum answer should not be determined by target barrel weight.
The answer should be determined by safety (minimum wall thickness) and then swing dynamics.

We know a great deal about barrel machining, and we we know that historically, the limiting factor was the combined effect of concentricity and wall thickness.

This is how I am proceeding with my "Chicken Gun" barrels.
I started with measuring the barrels. I had a local machine shop do this for me.
They laid out off of an imaginary line central to the bores. They provided me with concentricity, and wall thickness measurements at every inch, starting 5" from the breech. I elected 3 points at each segment. Top, side, and bottom.
That information drawn lifesize on a piece of roll paper showed me what I have for each tube.

My plan, before I was hospitalized, was to recontour the barrels to the shape of an H&H pigeon gun. I have the wall thickness measurements (sans concentricity measurements)of a nice example, and wanted to see if I could produce similar handling dynamics from an old Fluesie.
In the measurements, I found that my original barrels were bored approximately round, were relatively concentric, and that they showed areas where impact had altered concentricity. (repaired dents)

The next step is to choose surface grinding or filing to produce the taper. I believe surface grinding will get me closest, fastest, but there is something about the slip of the file.

My illness has delayed my next efforts, but I should be done with it by Sept.

Probably 2-3 hours,but I would be shocked if over 1-2 oz would be removed if it is a heavy barrel and deeply pitted.Some of the ones I have struck had metal removed only in grams.

Stallones, Would you characterize your work as "cosmetic" or working toward a different profile ?
Unlike rifle forums, we don't see alot of threads on this aspect of shotgun modification and repair here.

I'd like to buy a set of 20ga tubes from PeterDyson if this project works out.

Cosmetic for me to prepare for browning or blueing

A mathematician better than I could sit down and calculate the mass of removed metal using a calculator or some paper and ink. Maybe someone could figure that out for Tut. Since the wall thickness and outside diameter varies along the barrel, the calculations should probably be done in four inch sections. If the wall thickness is fairly even for the last 18 inches or so, it may be easier to take metal from the inside rather than the outside and hand strike the thicker breech section on the outside. A 20 gauge Fox gun should be able to lose quite a bit of thickness at the breech since 16 gauge barrels are fitted to the same action. The breech balls could be reduced to match the struck barrel breeches.

Tut, check out the stock and forearm on the Turner shotgun, gunsinternational.com item #100097211.

Now that is unusual indeed. That would certainly lighten the front end for sure.

weight reduction from striking the outside seems like a lot of work. Buy a different gun.

Assuming a lot. Iron,490lbs/cu.ft--4.5oz/cu.in,open circumference average (12 ga) --2in.; length --30 in.Then for each .001 in. removal--.06 cu.in or about .25 oz/barrel.So,to get 1 oz, both barrels need to lose .002 in. open area full length.That is if I kept all the decimals in the right place."Damm the decimal point" said the engineer as the bridge fell down.Chuck H is the cautious engineer,just get a different bridge.

Thanks for the replies thus far. Think the prudent thing is to consider both options. Working over the 16 Gauge, or working over the 20 gauge. I think myself and the action/wood guy will figure this out soon enough. Time is money and there's no sense in spending a bunch of time (i.e. money) trying to make something work. Guess you would call it a Bridge too far.

The only reason I ever had O/U barrels backbored was for weight reduction. Taking out .012-.014" removed nearly 5 ounces from a 32" set. The $400 at the time was worthwhile on a $3K clays gun. The people who do that kind of work are certainly capable but, at $200 per ounce I don't think I'd consider it on a SxS. I suppose you'd get chokes of your choice included in the cost, but I'd still consider another gun.

Think I'm with you Mike. The place doing the work has a couple of project Foxes available including a 16 gauge with 28" barrels. Might be able to pull off a trade. Mine was probably too nice for a project gun anyway. We will see what develops. PS. I've got an extra piece of Turkish that I don't need. There's lots of ways to skin a cat as they say.

Good calculations, WA!! I'd make a few changes, but they would not change the outcome by enought to worry about.

tut, are we talking about striking the outside (I understood pit removal) or is back boring an option. I'd backbore if inside is an option. If you need backboring calculations, post back.

Both. Just checked and minimum barrel wall thickness is stout .043. Lots of things can be done to these barrels to lighten them, the only question is whether its worth paying the expense to back bore and recut the chokes. Would be interesting to see how much you could lighten them up by just going to the standard .662 (they are currently .655). You'd still have a ton of barrel wall thickness for sure and would just be bringing the barrels up to normal bore diameter for a 16.

Mr Tut yah better check that wall thickness again. You write about a 16 gauge. I don't think any 16 would have .043 min wall thkness. This sounds like a heavy 10 gauge. Where did you measure ? What did you measure with ? CB

Let's see inside mikes at .655. Outside Mikes at .738 min. Subtract .738 from .655 equals .083 divide by 2 equals. .0415 min barrel wall thickness. What did I miss?? Measured with Frankfurt Digital Caliper. PS. That was measured about 6" from the barrel ends. Seems to me like number 2 16 gauge Fox barrels.

Mr Tut, a common mistake. Wall thkness cannot be measured as described. Your math works only if inside and outside dias are perfect round and concentric,not true in most cases. I wouldn't be surprised if the .0415 is realy about .030 if that .655 is correct. You ddin't say how you measured the inside.

Weight reduction for back boring: assume steel has 4.16 oz/cubic inch, ID = 0.655 so circumference (pi X D) = 2.06", for 30" bbls assume you can bore 26" (chamber @ 2 3/4" + cone @ 1 1/4"), bore area = 26" X 2.06" = 53.5 sq inches. Removed volume per thousandth = 53.5 in sq X 0.001" = 0.05 in cubed, removed weight per thousandth per barrel = 0.05 in cubed X 4.16 oz/in cubed = 0.22 oz --- say 1/4 oz per thousandth back bore per barrel. Going from 0.655 to 0.662 = 7 thousandths X 1/4 oz per thousandth X 2 barrels = 3.5 oz.

Questions?

Remember, when striking a set of barrels, the area between the ribs will not be thinned. Say maybe 25% of the o.d. will not be struck.

Inside was taken with a Skeets. Your indeed correct, without having a true ability to measure min barrel wall thickness, I'm guesstimating. Proof in the pudding will be when I take it to my Smith who has all the tools. With this barrel weight I'd be quite surprised if they are only .030 Min. I could see that if they were 4 weight barrels, but these have lots of mass.

That's pretty amazing and that would indeed drop her down to where she needs to be. Thanks.

I can add another 2 cents worth here.
Now that you have an approximation of the amount of material you can remove, you must decide from where you wish to remove it, and the effect it will have on your swing dynamics.

Since this is all tied to a custom shaped and stocked gun, the dynamics would be addressed in the overall scheme. Your indeed correct 100 percent.

Find someone with a gun that swings well for you, and then take a few measurements.
Oddly, for me, a gun I can hit with, isn't the same as one that I feel woozy about when I pick it up.

You are going to love seeing your ideas take form.

Tut, buy a Manson wall thickness gauge from Brownell's for about a hundred bucks and start striking. If one side is thick, take more from that side. If you're doing you own striking, you need the Manson gauge. If you want to use my Manson gauge to get a feel for it, let me know. My 6 1/4 pound Sauer ten gauge bird gun scares everyone who looks at it, but the barrels measure in the mid thirties. Figure that one out. Murphy

I have the nifty little program Tom Hammernick wrote for this very issue. If we can know the gun's pre-mod weight, balance, and MOI at balance (CG), then we can forecast the effect of changes. You also need to set targets for the modified handling values which says you need to know what you want.

What you shoot well as opposed to what you enjoy shooting is not one and the same for many, if not most, shooters. Don't feel like the Lone Ranger on this issue.

I'm gonna need a napkin Rocket :), and another Depends.
My gun design is specifically for shooting prairie chickens in the 35-50 yard range, on the rise. Not unlike the pigeon ring. 'Cept the bird is more frail.
The dynamic is weight forward, smooth, yet fast. 1.125ox loads of 6's at 1200fps. XF and F, which is where the extra weight forward meat came into the striking picture. Chokes bored for pattern, flat shooting. The Holland Holland videos, and how concentricity effected wall thickness and dynamics is a very welcome learning aid. They now can provide thicker (more durable) barrels with the same dynamics because they can control wall thickness so much more precisely. It's great stuff.

While I am saddened by the local machine tool economic collapse, I also welcome the available shop time and expertise.

Just looked at it. I think that would be money well spent indeed.

I think there's a math error in there. To enlarge the bore 7 thou, the wall is reduced by 3.5 thou. So the volume of the rectangular sheet in the above example comes from 2.06 x 26 x .0035, cutting the answer in half.

I skin the cat another way...

I figure the volume of a solid cylindrical rod with the larger diameter and subtract the volume of the solid rod with the smaller diameter, giving the volume of the 26" tube with .0035" walls that is the difference.

In any event, I believe the correct answer is 1.6 ounces.

Mike, I believe you are right. Thar in lies the advantage of "many eyes" review. Thanks. Both methods should yield the same answer - - - assuming you do the math right!!

You don't know how many sheets of paper I used before the two agreed.

Mike;
Thanks so much for your post. I used the same method you did ie subtracting the area of the current bore from the area of the .662" bore & multiplying my the 26" times two bbls & was coming up with your 1.6oz. I had not posted because I had kept going over R'mans figures & they all seemed correct. It had not yet sunk home where the discrepency lay. I soon as I read your post it just smacked me in the face, Why Sure, that's it.