- March 6, 2017 at 8:49 pm #33918WaksupiParticipant
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Apparently, there is little knowledge of what you are looking at, when you look through the bore of a firearm.
I learned how to inspect a barrel at the Bauska Rifle Barrel, Co., from Les Bauska.
He told me the way to train your eye, is to first look through a shotgun barrel. You will see concentric circles the length of the barrel.
These are light bars, and there are somewhere around 100,000 per inch.
On any good barrel, you will see these are all the same size for the length of the barrel.
On a crooked barrel, you can see the light bars are oblong in the bad part of the barrel. They will show you which direction
a barrel needs bent to correct things.
This holds true on a rifle barrel, although it is a bit more difficult to read for some. Others never can see it. The bore of the barrel is a polished smooth cylinder, just like the smoothbores.
You can train yourself to see the light bars, even with the rifling. Rough rifling is inconsequential, as long it is not cutting patches. Shoot it smooth, or lap it.
I’ve been the barrel inspector for three gun companies. I was able to teach some, but they were not common.
So, that gives you an idea of how to see if a barrel is straight. If you can’t see and understand what you are seeing, you are
swinging blindfolded if you need to bend the barrel.
- March 6, 2017 at 9:31 pm #33920GoodsteelKeymaster
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I trained myself on Easton X7 arrow shafting. Same principle, but I wanted to know how much I was looking at, and how much hook I could detect. So I intentionally bent the arrow shafts and measured how much the bend was on a surface plate with a test indicator. I found that I could find the apex of the hook within 1/2″ on the outside of the barrel, and I could detect as little as .005 hook. This has served me in good stead with shotgun barrels, but less than you might think with rifle barrels. I found that the critical part of a barrel is sometimes something that I cannot measure or detect, as I have examples of hooked barrels that shoot very well, and rough barrels that shoot very well, and badly crowned barrels that shoot very well, etc etc etc etc.
Obviously no barrel is going to shoot the tightest groups unless these things are all right, but having a good steady twist rate and a groove diameter that remains constant and a bore diameter that remains constant, seems to be the most important things regardless of barrel straightness.
It’s frustrating because several times I have built a rifle where the barrel seems straight, the internal finish is superb, lead slugs show me no tight spots and no looseness toward the crown, and a perfect chamber which I reamed myself, and the lousy SOB doesn’t shoot less than 2″! I can only attribute the failure to the one thing that I cannot measure, and that is the consistency of twist rate.
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