Barrel Lapping

Rogerbeep said:
Well I'll admit its is hard to convey without illustration...C'mon jerry I understand this thread is old but its got a lot of room for information....Really I'm not trying to create a pissing contest here.....
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I am not insinuating you are a pi$$er. I meant you are a contributor. We are missing a lot of accuracy potential in centerfire benchrest by not looking further into what can be gained by relapping SOME barrels. I always slug a barrel blank before I sink a tool into it. I have sent a few back to the barrel maker just from what I felt with the slug.
 
Quite simply, too smooth will foul as bad or worse than too rough. Sliding coefficient of a surface is not necessarily lessened by polish, many time the slipperiest surface has some contour. In gun barrels that contour has been established at around 220 grit, maybe 320-400 w/breakdown but POLISHED bores, bores brought to finer surface like600-1200 will foul IME.
 
Well I must have really missed the boat here as far as what grit size to lap at, but I'm not experiencing the fouling issue as a result of going all the way to 1200 probably since I'm using moly the (NECO method) and that's a another routine in it self, as I do moly the bore, bullets, as well as case necks, but that's a whole other topic and has its own followers.....
 
I wonder how much vibration is reduced from lapping and slick bullets...We go through the extent of trigger work, bedding, and hand loading the best loads, barking at the moon and is fitting to fall in place as a method to reduce vibration or make consistency of it IMO
 
Put a tuner on it if you want to get serious with controlling vibration. I think your barrel may be shot out before you have thoroughly tried all these things.
 
I find it unnecessary to use a tuner at this point with this rifle as it responded to each of the other steps done previously to lapping...If I remember correctly groups shrank after working up loads and then more after bedding then a little better after some trigger work i.e. 2 inch groups with fliers out to 3 inch @ 100 yrds, not even what I'd consider 'so so good accuracy but after lapping and moly prepping .5 inch with 200 gr Nosler partitions and accubonds hanging right in there too...
 
Not trying to snub you off Butch, but the rifle is right where I want it to perform..... Not ruling out anything, but If your talking one of those slide on tuners then I might add they may have benefits, but never aesthetically appealed to me.....If anything I add to this rifle it would be a Vias muzzle break, but now I'm afraid to touch anything at this point.....Thanks for your input. I appreciate everyone's posts here not in an attempt to revive this thread or steal someone's thunder, but to share their inputs in helping fill in some blanks as well. I'd like to thank Dave Brennan for Precision shooting reloading guide.... lots of stuff in that book, David Tubb for his contribution and tricks of the trade. And all those peoples brains I picked over the years from magazine articles to internet sites like this....I never tire of information regarding accuracy... Its never a dead horse to me. I cant count how many times I walked away thinking I had all the info I needed, when just in time someone added just the right piece of info I wanted.
 
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In the case of this particular rifle it was tough pulling 220 through in fact I thought I might get it stuck the initial pass...I cant imagine pulling 180.....Then I thought well it worked great for my .300 mag so why not do my CZ 527 in .17 rem so I stripped it down slugged it with a .177 cal. air rifle pellet it was as though it had already been lapped from the factory, so I did it anyway, but had to go to fine grits right away...no hang ups on that rifle...Not sure if they lap their barrels before they leave the factory...This rifle shoots under 1/2 inch @ 100 yrds so we bonded well....
 
What I am referring to is not an off the shelf abrasive/grease mixture. Perhaps yours was and the ratio may have been a little too stiff.
 
Boyd Allen said:
What I am referring to is not an off the shelf abrasive/grease mixture. Perhaps yours was and the ratio may have been a little too stiff.
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Not sure about how they at NECO or where ever they get it arrive at a ratio, but once its thoroughly mixed it suspends well. ' The resistance I attributed to the rough bore, as the first visible inch always had copper streaks and the resistance didn't let up till I was about 4 inches in....
 
Rogerbeep said:
Not sure about how they at NECO or where ever they get it arrive at a ratio, but once its thoroughly mixed it suspends well. ' The resistance I attributed to the rough bore, as the first visible inch always had copper streaks and the resistance didn't let up till I was about 4 inches in....
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Many/most barrel manufacturers that lap (a few don't) get their lapping compounds from US Products in Pittsburg, PA.

These are also the folks who make JB Compound and RemClean for Remington.

http://www.us-products.com/sitehtml/lapping.html
 
Very nice link Jerry....been meaning to comment about it some of the techniques described probably wont apply to barrel lapping, as far as polishing to that extent of course. I understand in certain applications may need that type of polishing.....There is so much in that read that I will have to read it more than a few times to extract more of what I need from it.....I wish I could find some up close photos of a number of lapping compound grit sizes and it would definitely be a bonus if one could see magnified photos of the grit impregnated on the laps.....I recall when I did my rifle I didn't charge the lap too much, just enough to coat it and made sure to thoroughly mix the compounds before use.....Like it says the secret is how much compound to apply to the lap to get the desired result....Again a must read!
 
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