hand lapping a barrel

[drknow65]

,first post) Befor asking my question let my bow slightly and tip my hat to the gentelmen gunsmiths on this site. Job well done. I've been all over the web searching for gun knowledge and I am impressed to no end to what I've found here.

My question is about hand lapping an extremely rough factory barrel on a remington 597 semi-auto 22LR.

I should also give a bit of background on the progression of this rifle. When I bought it and first took it to the range the gun would shoot 6" groups at 50yards,when I could get it to cycle). after disassembling the gun and polishing the rear of the bolt where it contacts the hammer when cycled, opening the groove for the striker so it wouldn't rub on the bottom of the bolt, and sanding the stock to remove horizontal pressure on the barrel and tightening the block that hold the barrel into the action, drilling through the reciever body and putting a set screw under the sear spring,so I can adjust the trigger pressuer externally) and installing a volqortsen extractor... the rifle now cycles consistantly and shoots 2-3" groups at 50 yards. I would like to see better but I will not put a $180 dollar barrel on a $150 gun.

I plan on first making a cerrosafe casting of the barrel to check the actual bore size,I'm hoping you could relay what it should be) and if it's acceptably tight enough to then make a lead casting to use with abrasives to lap the barrel. I'm not real worried about damaging the crown or throat as I've allready figured they are both sub-standard and will need redone eventually. If you could help me with technique/procedure I would greatly appreciate your help.

Also on a side note the cold bore shot will usually be 4" low and 1" left then work it's way up to zero in about four rounds and I've found that higher velocity heavier rounds are much more accurate with this gun,cci mini-mags solid point). Any help fixing this would be an added bonus.

 

[Spotcheck_Billy]

I don't pretend to be a gunsmith or a barrelmaker, but I was employed at a precision machine shop, first as an apprentice then as a journeyman machinist back in my misspent youth.

I learned enough to know that hand lapping is part skill and part craft and that it takes lots of training under an experienced tutor before you get it right.

Unless you plan to make this a vocation I'd strongly recommend that you take the easy way out on your .22RF barrel and purchase one of David Tubb's Final Finish rimfire firelapping kits. For further thoughts on this ammo with its abrasive coated bullets there's an interesting article by John Feamster in the April 2007 issue of Precision Shooting magazine.

 

[drknow65]

I appreciate the reply Billy, I also spent some time in a machine shop early on but never did and hand lapping other than to make surfaces perfectly flat... I had considered fire lapping the barrel but a few of the reviews I've read seem to indicate that the method works better on larger calibers. Either way I'd still like some advise on the technique and I don't want to proceed with any lapping until I have cast and measured the bore size,it's possible it shoots so poorly because the bore is already too large). Anyone know what the measurements should be?

 

[koginam]

fire lapping is simple with a 22lr. pull the bullet from a cci mini cap and roll it between two pieces of metal, or I use two mirrors, with rubbing compound until it is impregnated with the compound, then press back in to case and fire. Clean barrel and repeat if necessary using finner grits each time, most only take 3 times but several have taken more. I have used this method several times and I get a mirror finish, and have improved the accuracy of all the barrels as well as making them clean easier.

 

[brian923]

can fire lapping for other than the 22 lr cartridge be done with good effects to accuracy and cleaning?