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Apr 27th, 2024
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Joined: Feb 2002
Posts: 1,558 Likes: 22
Sidelock
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OP
Sidelock
Joined: Feb 2002
Posts: 1,558 Likes: 22 |
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. 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.
foxes rule
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Joined: Feb 2002
Posts: 1,558 Likes: 22
Sidelock
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OP
Sidelock
Joined: Feb 2002
Posts: 1,558 Likes: 22 |
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? That's pretty amazing and that would indeed drop her down to where she needs to be. Thanks.
foxes rule
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Joined: Jun 2006
Posts: 2,984 Likes: 298
Sidelock
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Sidelock
Joined: Jun 2006
Posts: 2,984 Likes: 298 |
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.
Out there doing it best I can.
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Joined: Feb 2002
Posts: 1,558 Likes: 22
Sidelock
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OP
Sidelock
Joined: Feb 2002
Posts: 1,558 Likes: 22 |
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.
foxes rule
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Joined: Jun 2006
Posts: 2,984 Likes: 298
Sidelock
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Sidelock
Joined: Jun 2006
Posts: 2,984 Likes: 298 |
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.
Out there doing it best I can.
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Joined: Feb 2002
Posts: 14,123 Likes: 198
Sidelock
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Sidelock
Joined: Feb 2002
Posts: 14,123 Likes: 198 |
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
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Joined: Jan 2002
Posts: 5,954 Likes: 12
Sidelock
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Sidelock
Joined: Jan 2002
Posts: 5,954 Likes: 12 |
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.
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Joined: Jan 2002
Posts: 5,954 Likes: 12
Sidelock
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Sidelock
Joined: Jan 2002
Posts: 5,954 Likes: 12 |
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.
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Joined: Jun 2006
Posts: 2,984 Likes: 298
Sidelock
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Sidelock
Joined: Jun 2006
Posts: 2,984 Likes: 298 |
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.
Last edited by ClapperZapper; 07/05/10 11:47 AM.
Out there doing it best I can.
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Joined: Feb 2002
Posts: 1,558 Likes: 22
Sidelock
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OP
Sidelock
Joined: Feb 2002
Posts: 1,558 Likes: 22 |
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 Just looked at it. I think that would be money well spent indeed.
foxes rule
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