Lapping Jig Setup

[LoneTraveler]

I made an adjustable lap set up I can attach to a cleaning rod and lap 22 RF barrels.
Does anyone have a picture or plans I could use to make a jig to set up the barreled action up on and have a dead stop on both ends so the lap will not come out of the bore on either end. I have sketch made of one, But why try to reinvent the wheel if someone already got plans for a good one. Thanks in advance.

 

[LoneTraveler]

I took my plans and made one. It worked OK on the first try, But had to remove the scope. Went back to the drawing board and added a barrel support and just use the rear action screw hole to hold it in place. I have worked on one gun with it and the flip over stop on the front stop is a cats meow, Allows easy access to recharge lap and tighten the screw in the lap.

 

[J E Custom]

The problem I found with stopping the lap at the muzzle was the reversing action seemed to enlarge the area where it is reversed.

All I could assume was that reversing it was turning the lapping compound and it was more aggressive in the beginning. so I started removing the lap each time i passed through the barrel (Much like some do with a bore brush when cleaning). on barrels that couldn't be shortened in this area. on barrels that can be shortened by 1/2 to 3/4'' It was not a problem. NOTE: Removing the lap each time it was passed through the bore was a pain and very timely.

Placing stops on the barrel is a good idea as long as you can solve the issue of over lapping some areas. the barrel makers are the experts and I guess the reason they want you to cut the muzzle end is because it solves this problem.

I only lap when there is no other option rather than risk screwing up a barrel. JUST ME.

J E CUSTOM

 

[LoneTraveler]

I agree with J E Custom, I should have stated the post a little clearer.
Lapping a barrel is when all the other bases for accuracy has been covered and good accuracy is still not possible. Action glass bedded, Action screws torqued to specs. Good crisp trigger, Good firing pin and spring, Proven scope, Scope rings and bases torqued to specs, Good rest, Good shooter and good ammunition.
You are down to two choices, 1. Make This Barrel Shoot Accurate. or 2. Remove barrel, Blue Print action and Replace The Barrel With a Reputable Manufactures Barrel. And Start over on the Quest for accuracy from the rifle.

 

[Gord0]

Reversing a lap in the barrel will always enlarge the area it has been reversed in. It's just like JE said about reversing a bore brush. The jagged crystals in the lapping compound flipping directions will eat into it pretty quick. Now if you intend to cut off the last inch or so after chambering and lapping, you should be all good.

 

[kiwikid]

The only lapping machine I have seen photos of was vertical rather than horizontal. Schultz and Larsen lap all their barrels with a cast tin slug. The last 100 odd strokes are stopped about 150 mm from the end of the barrel. This creates what is like a choke in the end of the barrel. All the S&L barrels I have shot shoot extremely well.

 

[shortgrass]

Hand lapped verses machine lapped. An experienced person who is doing the hand lapping has a 'feel' for what is happening, and can stop and examine his work. An automatic machine will just keep going, completing its designed cycle parameters without regard for the condition inside of the barrel. Machine operator verses a 'craftsman'. For sure, one has a lower cost than the other. Think hammer forging verses cut rifling, Boyds gunstock verses Alvin Linden gunstock, person with phone in one hand, who loads and unloads a CNC verses an 'old school' machinist with his hands on the wheels...……...

 

[LoneTraveler]

I want to thank everyone for their comments.
Some things that is mentioned are interesting and I will take in to consideration.

Just by my design, My lap has a machined washer measuring .220 diameter and about .1875 long and the screw head about .050 the lap never comes to the very crown edge of the barrel except when recharging with abrasive.

The lap I used is not poured, It is a thin strip of lead spiraled around the screw, Inserted into the barrel then the screw tightened forcing the lap to fill the void and take on the contour of the lands and groves, Before loading with abrasive.

The thing I found in this barrel was I formed the lap in the barrel muzzle with it greased I tried to run it though the barrel and hit a tight spot. Had to rewrap the lead strip and first fit it to the tight spot and lap it, Before I could lap the full length of the barrel.. I also at the end every 10 strokes marked the rod and backed up 4" each 10 strokes, Hoping to put just a little taper in the bore. My buddy had taken the rifle 2 time before. It started out 1 1/4 groups with Eley Subsonic HP. The last time He brought me a target at 50 yds,, 10 shots one hole about .375 diameter. Squirrels heads live a rough life now.

The pure tin lap was an interesting thing. I know from bullet casting adding tin to mix means less bullet shrink. Also for a big shop would not take a 100,000 dollar ventilation system to keep lead fumes from threatening workers health too.
Thanks again for all the comments. BDJ

 

[J E Custom]

One other note when lapping a bore. Most of the time it only takes one or two laps. on poor barrels it sometimes takes 2 or three depending on how bad the barrel is. The worst barrel I ever saw, had 5 of those tight spots and took 4 laps to clean up the barrel (I use standard (600 grit) lapping compound on the first lap then switch to non embedding 1000 grit Garnet to finish the barrel .

The worst barrel (5 tight spots) was only capable of 6 MOA groups so we had nothing to lose. After lapping we managed to shoot some 1.5 MOA groups with it. Barrel life had to be effected, But it was a hunting rifle for 3 to 400 yard shots and no more than he will shoot it, it could last a long time.

I like to cast the lap because I feel that It better represents the actual bore configuration. When I find a tight spot, I work through it and then cast another lap to uniform the barrel and get the desired finish.

Just the way I like to lap a barrel (If I have to).

J E CUSTOM

 

[LoneTraveler]

I have had good luck on a couple rifles getting good accuracy with lapping barrels.
I know now why as a job it would be a bad business practice. 12X shop hour charge= OH $#!(.
I just gave up on this barrel and looking at replacing it. I had spent about 12 hours taking apart, lapping, cleaning and replacing barrel and action in stock. To range and testing. 4 times. This barrel, 22 RF barrel has a groove that still collects lead after 2 shot and group starts opening. Time to make a property line stake out of it.
Thanks for all the help and pointers.