fire lap or old time lead lap Murata bbl?

[Depreacher]

What do, what do? The 7.62X54R Norma brass and the .329 Lee mould are on the way. Still trying to save $107 for the dies. It's not a sin to be poor, but it is certainly inconvenient at times. Should I cast some soft lead .329's and coat with extra fine valve grinding compound (which I have), or cast a soft lead lap on an old .243 brush. I know the procedure, as I have done it before, but I am lazy, OK! What do you think guys???? I wrapped 0000 fine steel wool around a .32 brush and gave the bore a GOOD scrubbing with pb blaster penetrant. It looked much better. It's shootable now, but would like to get it somewhat brighter. Still semi-dark.
I THINK (?) I can get by loading for it with my 8X57 seating die by running the seating screw almost all the way down. May not seat exactly straight, but will do until I can afford the dies. I have the shell holder. Will go through my collection to see what I can use to neck size the case. I'm not above using a seating die with the stem removed, using it as a neck sizer. I just happen to have a 8mm Lyman 310 boolit seater die/W7/8X14 adapter. So many gun projects. So little time. Any and ALL help is appreciated. Seems like I remember someone selling a firelapping compound kit. No boolits, just several grades of lapping compounds???? Can't remember. Preacher

[JSnover]

Wheeler makes the kit. You should be able to get it from Midway or Brownell's.

[725]

Not sure what the grit size is in valve lapping compound, but go very slow. I have used #600 & #800 grit to fire lap, and it went fast! I just took some old FMJ ammo and rolled it between two pieces of steel with a little grit and fired away. Clean the dickens out of it and then clean it again. I used lots of PB oil and lots of clean patches / wire brushes and spent a very long time cleaning out the grit. Go slow and stop before you think you are finished. You can always take it off but you can't put the metal back on when it's gone. Good luck.

[jlb300]

Tubbs is another firelapp system. I like the lead slug on a brush for hand polishing myself. It takes time as you are aware but you can feel the bore as you work the slug back and forth

[Depreacher]

So that's where it was. Midway! OK, THANKS. After reading the 3 posts, I believe I will hand lap. I had forgotten about the ability to feel the rough spots. I expect this 'ol sister has a few. Someday, all this will be behind me and I'll be posting my Muratas winning results from The National civilian championship match at Camp Perry. Everyone will be trying to sell their TUBB 2000's and buy a rifle like mine. Hey, I can dream!!! Preacher

[jlb300]

Have you gotten the murata up to snufff? I was wondering since it is winter and all I got little to work on right now and thought about it. How bout it preacher?

[pbbutz]

LBT has a set of rolling plates for rolling the grit into lead pills, they can then be seated by hand into the case with a very small charge--just enough to get it out of the bore. I have done this with a couple of bad bores and it worked very well. Hand lapping requires--I am assuming, experience--which I don't have and scares me a bit, while shooting a gentle loaded gritty pill cuts very slowly and true, if you believe Veral Smith of LBT, which I do.:drinks:

My .02, YMMV.

butz

[littlejack]

Very interesting thread. I have no expierience in fire lapping or using the soft lead slug to lap a bore. I do a lot of my own smithing and have been casting and loading for 40 years.
I have a M/N with a high spot in the bore. Would someone here tell me the procedure in making the hand lapping slug on an old bronze brush? All help appreciated and thanks.
Jack

[Bret4207]

I have far more experience hand lapping than any human should having been a slave in my Dad's gunshop. Unless you have a real need for hand lapping, like an odd constriction, I'd fire lap if I could. If you want a "choke" bore use lead alloy boolits. If you want to open the length of the bore use jacketed, at least that's the theory. Also watch it using those steel embedding plates. You can shrink a boolit with too much pressure.

[KCSO]

Fire lapping was invented by someone too lazy to push a lapping rod.
'nuff said

[littlejack]

Thanks for the replies. I do not want to steal this thread, I just need some information on what this thread is about.
I will let you'all be the judge of how I should lap the bore and also if It should even be tampered with.
I have a non- issued M44 carbine that I bought at a gun show. I sporterized it. I know that I have more money in the rifle than it will ever be worth, but I detest ugly guns. I removed the sights and had the barrell and action bead blasted and blued, so it now has a nice matte finish. I removed the bolt and mounted one to clear a scope. I replaced the stock with a Boyds walnut stock and installed a recoil pad. I installed a scope mount and a Leupold 2-7 Rifleman scope. I glassed in the action and recoil lug.
This rifle will shoot five Hornaday 150 grain .312 spire point into 1" to 1.25" at 100 yards. The bore slugs at .313. I clocked the velocity at 2800 fps, with a healthy dose of 4064. Yes you read right. That is with the 20" barrell.
I have been playing with it shooting Lyman 314299 bullets. I keep getting a couple of fliers with each group.
When I removed the front sight, I use a tig welder to fill the pin grooves in the barrell. This made a small high spot in the bore directly on the other side of the barrel wall where I welded it. The high spot is about 3" from the muzzle. I figure this could have an effect on the cast bullets, Maybe?
Should I leave it alone because it shoots so well with the jacketed or should I try to remove the high spot?
Jack

[Bret4207]

That is one of the exceptions where hand lapping would be the ticket IMO. Best advice would be try cast and see if they shoot first. If they don't and you have a gob of leading where the weld is then you have a candidate for hand lapping. It's going to take time and effort and you may have to recrown after word. There is the chance you'll bell the muzzle just forming the lap and getting it down to the constriction. It would be best if you could figure which lands and grooves are distorted and only put cutting agent on that area rater than the whole lap. You decrease your chances of belling that way.

[littlejack]

Bret:
Thanks for the reply.
When I shoot the cast bullets, there is absoluetly no leading in the barrell. Even where the slight constriction is, no leading. These bullets leave the bore shiny and clean.
I agree with you on putting the cutting agent on just the area where the constriction is.
I still need the procedure on how to make the slug using the bronze brush to do the job. If you have another method of making the lapping slug, I would appreciate how to make it and the procedure to use it.
Jack

[Bret4207]

Basically you center your lap spud in the bore near the muzzle and have a plug behind it. The pour your alloy around it. Trim off anything that will keep it from entering the muzzle and go from there, A witness mark on the lap and barrel will get everything lined up right. Apply you lapping compound, valve grinding compound is what I recall using, and tart lapping. If you're going from the muzzle try to use a centering device and be aware that lap is still cutting even when it feels like it isn't . You might get 25 passes, then it's time to pour a new lap. Run a slug through to feel how much it's cut. If all you want to do is that rough spot it won't take long, but it won't take long to screw things up either.

[dubber123]

Thanks for the info, I always wondered how the laps were made too. I'm one of the lazy ones that firelaps, (In your eye KCSO!). I have only recently gotten brave enough to do so, but have been very pleased with the results.

I didn't buy a kit, I just used some 1/4" steel plate I ran on the belt sander for a minute, and some valve grinding compound. I used air cooled WW's too.

[jlb300]

I dont seee it mentioned but I was taught to heat the barrel before pouring in the lead. This will cause the barrel to shrink a little tighter,after it cools, to the slug getting more ,or maybe better, contact during the lapp? Any other input?

[dubber123]

I dont seee it mentioned but I was taught to heat the barrel before pouring in the lead. This will cause the barrel to shrink a little tighter,after it cools, to the slug getting more ,or maybe better, contact during the lapp? Any other input?


Scroll farther down the list in Military Rifles, part way down on page 1 there is another thread on lapping, and it contains a much more in depth description of the process. :drinks:

[Depreacher]

Hello all,

I'm the idiot who started this thread, and thought it ended months ago. Haven't visited the Military forum in a while, so please forgive. I hand lapped the bore from the breech after casting the lap at the muzzle. The barrel had a tight spot 2/3 way up from breech. Had to cast several laps but finally "got it". Shot a 3 shot group at 45 yards 2 1/4" c to c. This was with a horrible front sight which had flattened on top. Best excuse I can come up with at present!!!
$3.25 per case is slowing my ammo aquisition, but Obama may cure that. Only had 3 cases, so loaded 21 gr. 4759 behind Lee .329 unsized at .330. Proof load was 24 gr. 4759. The bore now grades at fair to good.