barrel crown question.

17asleep

17asleep

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First post here, so hello to all.

How much dammage to the crown would it take to make a rifle group like two feet at thirty yards? I built a 17 remington off of a Savage 340b action with a stainless steel Remington barrel and now the damn thing wont hit anything unless I am pretty much touching the target with the barrel. I have checked everything that I could think of and not found anything that would cause such horrible acurracy except for some minute imperfections on the rifling right at the muzzle. Could this combined with the tiny bullet and extreme velocities be casuing my problems? Any thoughts?
 
Did it ever shoot well before or after you built it? The crown is very important. It is the last thing done after barreling so you know it is okay and not damaged by centers of anything.

If it shot okay and suddenly is really bad, you may have a bulge very close to the muzzle... that really screws up accuracy.
 
I never actually sat down to shoot it to check the accuracy before on the first twenty rounds I fired out of it, although I fire two shots at a paper target and put them both roughly into the same hole at 75 yards, so I am guessing that it just happened all of a sudden. The rest of that box of ammo killed some dirt and some rocks and a skunk. When I think about it, the skunk must have been the last shot that went even close to where I wanted it to and that was round number 17 out of 20. The last three shotsfrom that box of shells were aimed at rabbits at about 125 yards, and those rabbits are still doing what rabbits do best, as far as I know.

So if I do have a bulge in the barrel, is it toast, or what? Also, how can I check to see if that is actually the problem? Take it to a gunsmith?
 
First thing I would do is make sure the bedding screws are not bottoming out before the action is firmly in the stock. Put some magic marker on the end of the screws and tighten the action into the stock. Remove the screws to see if the marker has rubbed off. If so, shorten the screws a thread or two. Next would be the scope. After that I would check the bore for fouling. 2 ft groups at 30 yards sounds like more then a crown issue to me.
 
Fired acouple shots yesterday and boresighted the scope. it was dead on. The bedding screw is tight and now that you mention that it reminds me of something. See, I got the barrel and the action and a broke stock off a guy who lost interest in the project and I carved a new stock for it out of a piece of walnut that my uncle gave me when I told him about what I was planning to so. Carving the stock took pretty close to a year of whittling on evenings, somtimes not having time to work on it for monts at a time. So while the stock was in process I was actually able to use the rifle some because I had inletted the action and roughed the blank in the first month and spent the rest of the time finishing. All the shooting I did previous to about a month ago was with factory ammo with the action glass bedded but still no bottom metal in place. ( I had to make that, too. Easy when you have about 4 million dollars worth of metal munching equipment at your disposal.) I bought reloading dies on ebay and installed the bottom metal in the same week and that is pretty much the first time I sat down and did some serious target shooting for load developement. It's also the first time I knew for sure that something was terribly wrong. Now I wonder, could the action screw against the bottom metal be making such a huge difference from when I had it against the wood? Possible? ####, I just remembered, too that I inletted the bottom metal, so the action screw will probably be too long to use without it. Wooden Washer?
Shorter screw?
Any input?
 
Shorten the screws a few threads if they are bottoming out. Torque to 65 inch pounds and make sure the action is not hung up by the bottom metal.
 
I took the bottom metal off and replaced the screw and it was still short enough to work, but I fired two shots at 40 yard and the first one went a foot high and the second one went 8 inches left. so not the screw or the bottom plate.
Isn't the screw issue something that would give me 5 or 6 inch groups rather than 12-18 inch?
 
You need a dewey rod, a brass jag, maybe some nylon brushes, some patches and some serious bore cleaner ie JB paste, Sweet's 7.62, Shooter's Choice. A bore snake will not do a serious cleaning job.
As you have looked closely at the crown, did you notice any copper fouling on the lands?
I have never used a Bore Snake and never will.
 
Have looked really closely at the crown and never noticed any copper. I use moly-coated bulletts, by the way. Dunno if that makes any difference or not.
 
guntech said:
If it shot okay and suddenly is really bad, you may have a bulge very close to the muzzle... that really screws up accuracy.
Click to expand...


I removed the barrel from the reciever and had a really close look at it in good light and I noticed that there is a definite ring of SOMETHING about an inch and a half back from the muzzle. It's not a whole lot, only about a quarter of an inch of the barrel seems to be affected. Whould a bulged barrel be that obvious or whould I not be able to see it with the naked eye?
 
What you are describing sounds like a pressure ring. If you had something in the barrel, you can get a localized spot of high pressure that leaves a groove at the blockage. It may or may not leave a bulge on the outside of the barrel. The ring is a groove perhaps 1/8: front to back.

cheers mooncoon
 
I have heard of .17 calibre bullets shedding their jackets in the barrel. Thousands of rounds through my HMR and it has never happened to me, but a reliable friend described a similar problem and claimed to have found a ring of copper pretty well welded into the barrel. I can't remember what his solution was....
 
mooncoon said:
What you are describing sounds like a pressure ring. If you had something in the barrel, you can get a localized spot of high pressure that leaves a groove at the blockage. It may or may not leave a bulge on the outside of the barrel. The ring is a groove perhaps 1/8: front to back.

cheers mooncoon
Click to expand...


Exactly what I am seeing.
 
I got up from the computer and took her to the lathe and machined it down to where the ring was. I had to take off two inches before I was satisfied. NOw I guess It's time to reassemble it and test fire it. I probably wont get a chance to do that for almost a week, but will try to report back when I do. Thanks to all who chimed in.
 
17asleep said:
I removed the barrel from the reciever and had a really close look at it in good light and I noticed that there is a definite ring of SOMETHING about an inch and a half back from the muzzle. It's not a whole lot, only about a quarter of an inch of the barrel seems to be affected. Whould a bulged barrel be that obvious or whould I not be able to see it with the naked eye?
Click to expand...

If you are seeing a shadow ringing the bore... that is a bulge, caused by an obstruction of some kind when you fired a round ... You may be able to feel it on the outside ever so slightly...
 
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