This barrel has never been a tack driver, BUT it's capable of some good groupings. Shall I do some crowning?
Suggestions are accepted.
Suggestions are accepted.
Tuning To Crown or not to Crown, that is the question!
- Thread starter barreira
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When I zoomed in, I squirmed in my seat a little.
Brass screw method would be appropriate if the problem is just at the end of the rifling. However if it has the rifling smeared down into the bore, it will need to be chopped back to clean rifling and then crowned.
Brass screw method would be appropriate if the problem is just at the end of the rifling. However if it has the rifling smeared down into the bore, it will need to be chopped back to clean rifling and then crowned.
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I would 100% minimum hit that with a brass screw. And in my experience if the crown looks like that the other end could almost certainly need some smoothing.
I have had more than one barrel that the lead in caused accuracy issue by trashing pellets before the crown even had a chance to screw things up.
I have had more than one barrel that the lead in caused accuracy issue by trashing pellets before the crown even had a chance to screw things up.
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I have experience with recrowning barrels . I have had some excellent shooters that lost accuracy that were recrowned , I have tried the screw method and have not had good results . I shoot bench rest matches so I am looking for the kind of accuracy that can win matches. Dont waste your time trying to recrown yourself with a screw . Take the barrel to someone with a lath and have them take a few thousands off the face of the barrel to square it and cut a small bevel with the lath . It does not take long to do and should not cost much . I get them done for $15. A crown must have absolute precision for top accuracy .
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I’m not a gunsmith and you did not mention if your friend with lathe is. I do have a lot of lathe experience, but not on gun crowns. Be sure the tool is very sharp, as in freshly sharpened and then the final facing should start from the bore and face outward towards the OD.
Probably a bunch of other tricks of the trade too that I don’t know of on re-crowning.
Probably a bunch of other tricks of the trade too that I don’t know of on re-crowning.
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He's a profissional lathe machinist but he is not a gunsmith.
I have to give him your advices about the crowning.
I have to give him your advices about the crowning.
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After he makes the cuts, have him take a very fine piece of emery cloth and press it into the crown with his finger tip to polish it while spinning in the lath
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And most importantly tell Him that You have to center the barrel from BORE, NOT from outside surface.
Jeff can show You:
Jeff can show You:
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@Sharp Pog
We are in the same area of the country
May I ask who you bring your barrels to for crowning, please?
Thanks
Edward
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I did diy re-crown my barrels and liners with a brass screw method, yes improved the POI but that is just a half job done.
Push a pellet through the rifling as shown in the video and grab some higher power jewellery lupe and take a look the pellet skirt.
You will see the rifling "footprint" on the pellet head and skirt edges, but .... inspect the bottom of the skirt edge as well... do you have an even flat - planar skirt or the softer lead got deformed and you got overhanging "tailes" around the perimeter? If the later - you can imagine the after effects of a blow-by at the crown/muzzle exit....
Push a pellet through the rifling as shown in the video and grab some higher power jewellery lupe and take a look the pellet skirt.
You will see the rifling "footprint" on the pellet head and skirt edges, but .... inspect the bottom of the skirt edge as well... do you have an even flat - planar skirt or the softer lead got deformed and you got overhanging "tailes" around the perimeter? If the later - you can imagine the after effects of a blow-by at the crown/muzzle exit....
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To supplement what @bigHUN is describing, here are some examples of lead smearing behind the skirts resulting from an untreated leade.
If you're interested, a few of the common barrel workmanship topics are covered in this writeup:
www.airgunnation.com
If you're interested, a few of the common barrel workmanship topics are covered in this writeup:
Barrel troubleshooting and accurizing guide
The following article is intended for the do-it-yourselfer that is interested in either finding and fixing a problem with a barrel, or improving the accuracy of an already good performer. You don't have to be a master machinist to get excellent results. The techniques described here can be...
www.airgunnation.com Upvote 0
The barrel in the OP's opening needs crowned if it shoots bad. The first thing I do is shoot the gun and see what groups I have. To touch up a crown that puls fibers off a Q-tip I use a brass piece cut at 45 degrees and valve grinding compound in a lathe. I bump it with the tail stock crank a few times to get an even bevel. That is all I have had to do so far with my rifles. I do not crown unless I can't get it to shoot.
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