Do It Yourself Counter bore
I had a little cleaning mis hap and scratched the "perfect" crown on my 91/30. Only two tiny scratches, but one of them seems to be very close to the rifling and both of them are just inside the bore. Should I use a drill press to ever so slightly counter bore the rifle? I have not shot the rifle since the incident, but with all I have heard about how important a good crown is, I figure I am in trouble as it stands.
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Me I'd go with a diamond impregnated burr. Less chance of catching and wang chungin your barrel. 0 -
For a cleaning scratch I would buff it out. 0 -
Shoot it first to see if accuracy has been affected. 0 -
brier-49 has it right. Shoot it first to see if accuracy has been effected. Chances, the "perfect" crowns on those rifles, can be enhanced by a scratch or three.
If I am not mistaken, that is a bolt rifle, and can EASILY be cleaned from the breech to the muzzle. Doing so, almost totally eliminates the chance of a "cleaning mishap", and the subsequent crown enhancement you have provided to this rifle.
Lastly, counterboring in a drill press, WILL result in less than satisfactory results. In effect, you would be BUBBADIZING it more than it already has been. A crowning tool, and bore guide of the proper size, will be needed to correct this with the barrel still on the rifle. The absolute proper way to fix it, is to take the barrel off, and lathe cut the crown.
Best0 -
DO NOT use a drill press. My advice is take a rod with a good JAG not one of those split where you fold a patch and run through a slotthen from the chamber end using a patch with J.B. bore cleaner push the rod down the bore until the Patch sticks out the end of the muzzle about l/4 inch then LAP the very end of the bore with one inch strokes this will smooth the crown at the very end of the bore . 0 -
7.62x39Lover,
Let's weed through some of this:
- Shoot the rifle first since the possibility exists that the scratches will not affect the crown.
Here's where I don't want to offend folks but...
- Never use a drill press on a rifle crown, EVER!
- No diamond impregnated burr or any other tool without a bushing.
- Never lap the crown of a barrel from the inside or the outside.
The correct idea is to cut the crown perpendicular to and concentric with the bore of the barrel.
Crowns are cut, not ground, lapped or polished, no matter what the supposed experts want you to believe. This 'junque' about using brass screws with lapping compound in a drill motor or ball bearings and lapping compound or lapping the bore at the crown is just not done if you want the best crown.
The best method is to set the barrel up in a lathe, indicating the bore in to true. Then simply cut the crown shape of your dreams and re-assemble. A growing number of builders are now using crowning tools with bushings which are interchangeable to fit the bore precisely. These can be run at very low speeds on the lathe for best results.
No matter what method you choose, try shooting the rifle first before deciding.
If you have any more questions, ask away.
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Aren't those things chrome lined? Might it not cause problems for the chrome to end right on the edge of the crown? 0 -
Mosin 91/30s aren't chrome lined. 0 -
What do you guys think of Manson Precsion Reamer kits?
www.mansonreamers.com0 -
For? I think you should shoot it first and see if it has been effected. Then if it has, for a fraction of the cost of the tooling to do it properly(and there is no gaurantee that it will be done properly, with no hands on experience, and/or training), you can have it done by a competant full service shop.
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I am so anal about my guns that just the fact that the scratch is there is mental torture. Perhaps it won't affect accuracy.
I will definitely shoot it sometime soon and get back to you guys.0
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