N/A lapping a barrel
- Thread starter Groucho7
- Start date
Dillon, clearing the burrs with a fine abrasive like J-B bore compound, it would be tedious, yes. Still less time than packing up the barrel and making arrangements to have someone else do it. Besides, what do you have to loose for having tried other than a half hour of your time? If the result is not satisfactory, you can still send it off.
BTW, not that I recommend it but here is a silly experiment to see what a 10-second crown job can be. Inspired by the atrocious crowns many people were getting on the cheap Crosman Icon PCP, I grabbed a barrel in the shop and hit it 3 seconds with a carbide burr followed by 7 seconds with a diamond ball.
The result is vastly better than a lot of production barrels I’ve seen. Which is sad when you think about it.
BTW, not that I recommend it but here is a silly experiment to see what a 10-second crown job can be. Inspired by the atrocious crowns many people were getting on the cheap Crosman Icon PCP, I grabbed a barrel in the shop and hit it 3 seconds with a carbide burr followed by 7 seconds with a diamond ball.
The result is vastly better than a lot of production barrels I’ve seen. Which is sad when you think about it.
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If your going to disagree then publish the rule please.
Let me rephrase my opinion: "Good golly, not another example of embedded opinion rooted in only one understanding of a subject then held so rigidly as to not allow other examples of the same outcome to be published."
Better?
Exercise common sense and be considerate towards your fellow users. The diversity of opinion and intelligent civil discourse is encouraged; by the same token: rude, lewd, vulgar, obscene, flaming, baiting, trolling, hateful, threatening, insulting, violent, or slanderous content will not be tolerated. You may challenge others' points of view and opinions, but do so respectfully and thoughtfully
Let me rephrase my opinion: "Good golly, not another example of embedded opinion rooted in only one understanding of a subject then held so rigidly as to not allow other examples of the same outcome to be published."
Better?
Exercise common sense and be considerate towards your fellow users. The diversity of opinion and intelligent civil discourse is encouraged; by the same token: rude, lewd, vulgar, obscene, flaming, baiting, trolling, hateful, threatening, insulting, violent, or slanderous content will not be tolerated. You may challenge others' points of view and opinions, but do so respectfully and thoughtfully
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You bring up a good point. If I have JB paste I might as well try it out. I'll need to see I remember buying a brass screw years ago to try to do it on a SPA gun but don't think I ever did use it.Guess it wouldn't hurt to try.
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Turns out my memory ain't half bad. Well at least for this specific thing lol Wasn't gonna ship until tomorrow anyways so guess I'll give a try tonight when I have time.
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That combo should do the trick. Just plan to refresh the abrasive often (I.e. just add more) since J-B breaks down quickly into smaller particles. If you have a stick of medium polishing compound like the kind you load on a benchtop polishing wheel, you can scrape some of it off with a knife and mix it into a slurry with the J-B and that may help speed things along.
The two things to keep in mind are
The two things to keep in mind are
- Don’t bear down...try to maintain just the lightest of contact and let the spinning motion and abrasive do the work. If you want to apply pressure early on, that’s okay but ease up as you near completion.
- Orbit the drill randomly. This approach helps ensure you get a uniform bevel. (If instead you try to hold the drill steady, the bevel will end up biased in some seemingly random direction).
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Brother I want to thank you! What an amazing difference. It was much easier than I thought it was going to be. I have learned an important skill and have you to thank for it!
Yesterday's "shot groups" at 50yds
Today's after recrown. First 2 large groups were 10 shots and seemed the barrel needed to settle? Or just me. The rest all 5 shots with 3 different pellets. Slight variable winds right to left
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Very nice! You're a natural.
Pretty cool to see the before and after, both the closeup of the crown and the results on target. With any luck, your effort will inspire someone else who has been on the fence.
Pretty cool to see the before and after, both the closeup of the crown and the results on target. With any luck, your effort will inspire someone else who has been on the fence.
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Perhaps I missed it earlier Dillon but what rifle is that barrel from? Congrats on a great crown job and a significant improvement.
Did you try pushing a new pellet through it after the work?
Did you try pushing a new pellet through it after the work?
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Thanks! Yes I hope others will be inspired to do so also. Was always hesitant to do so but glad you nudged me to give it a try. Did take at least 15-20min on it spread over I think 10 different times of around 2min. But like said worth the time and effort and learned something new.
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Taipan Veteran Long .22. And thanks! I did. I pushed a few as I went along doing it and got it to the point where you can't really tell a difference between pushing up to the crown and fully through. I now reach the crown and just a tiny bit more effort pops through. Before I had to really push. I'm sure my fps on my tune bumped up too. I'll need to check that.
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If you exxpress that advice in a public appearance, you should expect many requests for your autograph.
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You’re pouring the molten lead onto a jag (or similar thing) at the end of a cleaning rod. After it has cooled, you apply abrasive to the cast lap and use the cleaning rod to work it back and forth. I included a few pictures of my setup in the following thread:
Attempting to rescue a bad barrel - the SPA M25 in .35 cal
Well I finally got a chance to revisit the .35 cal SPA M25. It's been mothballed for a while....when I set it aside, it was still producing poor groups after having taken a first pass at correcting the poor factory crown and working the bore with a cast lap. That history is covered in this...
www.airgunnation.com Upvote 0