Link to fire lapping question

[Marlin Junky]

I though I'd get a few more responses to the following question if I linked it to a more frequented forum:

http://castboolits.gunloads.com/showpost.php?p=1093398&postcount=55

This is my first fire lapping experience and I'm doing it to a collectible rifle, so I'm a bit nervous.

Thanks for your advice...
MJ

P.S. Pre-64 M70 in 30-'06

[243winxb]

what firearm?

[outdoorfan]

I'm not familiar with those powders. I use Red Dot. A fast powder is best, and yes, some dacron helps too. I use the chronograph to dial it in. 10-12 bhn non-bore-riding bullets and have at 'er.

If you stick one, don't freak out. You can remove it. However, if you start on the high side of the velocity scale then you can work your way down to get it just right.

[Marlin Junky]

I loaded up some rounds with the 154 grain boolit that came with my BT lapping kit, which look like an LBT design, 4.0 grains of Scot 453 (very similar to W-231) and 1 grain of Dacron. Will see what the chronograph has to say tomorrow. QuickLoad says 850 fps but that would really surprise me. I lubed the boolits with BAC so I could get them in the cases easily.

The next question is: how much will the coat of 320 grit slow down the boolits?

MJ

[outdoorfan]

You're approaching this from a scientific methodology of trying to accurately determine muzzle velocity or the absence of it before you even get to the range. I have the apparatus that I bring with me to the range to completely do my loading there. That way I'm loading one round, shooting it, then adjusting powder charge for the next one. And doing practice shots without lapping compound is more time consuming and won't necessarily get you any closer to where you want to be in the end. Your mileage may vary.

[Marlin Junky]

You're approaching this from a scientific methodology of trying to accurately determine muzzle velocity or the absence of it before you even get to the range. I have the apparatus that I bring with me to the range to completely do my loading there. That way I'm loading one round, shooting it, then adjusting powder charge for the next one. And doing practice shots without lapping compound is more time consuming and won't necessarily get you any closer to where you want to be in the end. Your mileage may vary.

I wish I had some portable reloading equipment. Anyway, I averaged 724 fps with the un-gritty boolits today. I'm thinking 3.5 grains should be just about right for the 320 grit boolits.

MJ

[BABore]

I load one up, poke it out the back door, and if I can see the boolit in flight, I'm good to go. You just need to get it out the bbl reliably and that's it. Not rocket science here.

[Bass Ackward]

Rough barrels polish easier than smooth. So another way of saying this is, smooth barrels require more powder charge to get them to exit.

[outdoorfan]

I wish I had some portable reloading equipment. Anyway, I averaged 724 fps with the un-gritty boolits today. I'm thinking 3.5 grains should be just about right for the 320 grit boolits.

MJ

I have a Lee hand press that works great for this, although I bet the fit between the bullet and case neck is sloppy enough to drive the bullets in by hand.

I took a piece of wood, drilled a hole in it big enough to fairly snuggly fit the base of the case in it, then drilled a smaller hole in the middle of the bigger one (to allow the primer to exit). This allows me to easily deprime using some kind of a punch while at the range.

As far as measuring powder, I just use a dipper. Doesn't have to be perfect. Once I get it dialed in I'm usually pushing them out at around 500 fps.

Good luck!

[Marlin Junky]

I'll try 3.0 grains tonight. What about seating depth? 2.875" COL is just off the rifling but not all the grit is covered by the case neck.

MJ

[Bass Ackward]

I took a piece of wood, drilled a hole in it big enough to fairly snuggly fit the base of the case in it, then drilled a smaller hole in the middle of the bigger one (to allow the primer to exit). This allows me to easily deprime using some kind of a punch while at the range.


I just carry the correct size nut in my pocket.

[geargnasher]

MJ, it isn't rocket science. If the boolit exits, it exits. Worse case it sticks, you wait an hour before opening the bolt, and you tap it out with a tape-wrapped steel rod and mallet. Add another grain of powder and have another go.

I have done this to several rifles, and as a basic rule I use about three grains of any fast powder, a grain or so of Dacron, unsized case fired from that gun, start the lapping boolit in the case with my fingers and breech seat it. Take a bead at a stump across the back yard and squeeze her off. If I get a "lube star" of Clover Compound on the muzzle the velocity was about right. Just barely enough to get the boolit to clear, no more. Takes about 20-40 rounds to go it right.

One more tip if you can't shoot at home, take the decapping rod from a pistol die set (no expander ball) and the shellholder for the cartrige you're using for a punch and base set, and a hand primer. Take your powder, Dacron, and prepped boolits to the range with you.
Gear

[crabo]

I just carry the correct size nut in my pocket.

I always carry a couple with me.... sorry, couldn't resist an opening like that.

[outdoorfan]

I just carry the correct size nut in my pocket.


So simple it's embarassing. :oops: I'll have to do that next time.

[BABore]

I'll try 3.0 grains tonight. What about seating depth? 2.875" COL is just off the rifling but not all the grit is covered by the case neck.

MJ

First off is you don't size your cases. The low power of the lapping load is not usually enough to expand the case neck to seal. When this happens, lapping compound gets blown back into the action making cleanup a bigger chore. Seat the boolits to whatever. It don't matter at all. Hell, I've even had them slip into the case so they were flush with the case mouth. It is extrtemely important to use boolits that are between 10 and 13 bhn. Too soft of a boolit deforms too easily under constrictions and doesn't cut right. Too hard of a boolit springs back too much. Deprime, and reprime your cases with what ever junk primers that still will go bang. Add about 3 grains of Red Dot and put a tuft of Dacron on top the carge to hold its position. The Dacron also will help wipe some of the **** out the bbl. Roll your unchecked boolit well. It usually takes 2-3 minutes of rolling per boolit to do it right. To see if you did it enough, wipe the compound off the boolit. The driving bands should still be black. Fill the lube grooves with lapping compound. I seat the boolits with a piece of 7/8-14 thread rod with a flat face. Don't use your regular seating die if you can help it. You don't need it contaminated with lapping compound. I only load 5 at a time and fire them from a perfectly clean bbl. Clean completely and repeat. If your just smoothing up the throat area, it will only take about 5-10 shots. Doing a full bbl, to acheive a tapered bore, may take 30-35 rounds. Inspect the machining marks at the muzzle prior to starting. Take a pic if necessary. When you JUST start to see them clean up. STOP.

When I'm done fire lapping, I do a complete cleaning. Then I take a bronze brush and wrap it with a long strip of cotton from old skivvies. It should be a tight fit to the bore. Coat this mop heavily with lapping compound and give the bbl 100 strokes in rapid succession from the breech end. Clean again and your ready for a new bbl break-in. It takes about 2-3 hours to do a complete job.

[Bass Ackward]

If your just smoothing up the throat area, it will only take about 5-10 shots. Doing a full bbl, to acheive a tapered bore, may take 30-35 rounds. Inspect the machining marks at the muzzle prior to starting. Take a pic if necessary. When you JUST start to see them clean up. STOP.

When I'm done fire lapping, I do a complete cleaning. Then I take a bronze brush and wrap it with a long strip of cotton from old skivvies. It should be a tight fit to the bore. Coat this mop heavily with lapping compound and give the bbl 100 strokes in rapid succession from the breech end.


We are pretty close except I cheat.

I do your underwear trick first and then I fire lap. Takes less shots that way and the fire lap straightens out anything I messed up.

My last step is to fire regularly lubed, hard lead bullets at low velocity to remove any abrasive stil in the bore. Then I clean.

[BABore]

We are pretty close except I cheat.

I do your underwear trick first and then I fire lap. Takes less shots that way and the fire lap straightens out anything I messed up.

My last step is to fire regularly lubed, hard lead bullets at low velocity to remove any abrasive stil in the bore. Then I clean.

Figgers! You are known as "Ass Backwards". Oops! I meant Bass Ackwards.[smilie=1::mrgreen:

[geargnasher]

BABore, if you made a formalized version of that and posted it somewhere I'd sure clamor to the mods to make it a sticky, your advice on firelapping saved me a ton of money, time, and kept me from screwing it up. I've revived three great old rifles using your method.

Gear

[Marlin Junky]

First off is you don't size your cases. The low power of the lapping load is not usually enough to expand the case neck to seal. When this happens, lapping compound gets blown back into the action making cleanup a bigger chore. Seat the boolits to whatever. It don't matter at all. Hell, I've even had them slip into the case so they were flush with the case mouth. It is extrtemely important to use boolits that are between 10 and 13 bhn. Too soft of a boolit deforms too easily under constrictions and doesn't cut right. Too hard of a boolit springs back too much. Deprime, and reprime your cases with what ever junk primers that still will go bang. Add about 3 grains of Red Dot and put a tuft of Dacron on top the carge to hold its position. The Dacron also will help wipe some of the **** out the bbl. Roll your unchecked boolit well. It usually takes 2-3 minutes of rolling per boolit to do it right. To see if you did it enough, wipe the compound off the boolit. The driving bands should still be black. Fill the lube grooves with lapping compound. I seat the boolits with a piece of 7/8-14 thread rod with a flat face. Don't use your regular seating die if you can help it. You don't need it contaminated with lapping compound. I only load 5 at a time and fire them from a perfectly clean bbl. Clean completely and repeat. If your just smoothing up the throat area, it will only take about 5-10 shots. Doing a full bbl, to acheive a tapered bore, may take 30-35 rounds. Inspect the machining marks at the muzzle prior to starting. Take a pic if necessary. When you JUST start to see them clean up. STOP.

When I'm done fire lapping, I do a complete cleaning. Then I take a bronze brush and wrap it with a long strip of cotton from old skivvies. It should be a tight fit to the bore. Coat this mop heavily with lapping compound and give the bbl 100 strokes in rapid succession from the breech end. Clean again and your ready for a new bbl break-in. It takes about 2-3 hours to do a complete job.

Thanks for the tips Bruce. It's too late on the not sizing part though. I've already got 25 rounds loaded up for tomorrow but the only sizing was with a Lee Collet Sizer that provided just enough tension on most case necks to hold the 320 grit boolits in place. Most of the necks wouldn't even touch the sizer on my 31 M-Die. Some of the boolits provided a bit of resistance though when seating. These boolits were from Beartooth and specifically for fire lapping; i.e., BHN 12. I ran them though my .310" 450 die (normally sizes normal boolits to .3105") to true them up a bit and most of them 'miked' around .311" after rolling them in the grit. Few of them are round though which kinda makes me a bit nervous. I didn't fill the grooves with lapping compound so maybe I won't have too much of a blow back issue. The neck area in this particular '06 is so wide that a .314" boolit will drop inside a fired case.

There's some strange tooling-**** (I guess) going on near the muzzle of this rifle and after firing 3, 5-round strings I don't notice any difference, I'm going to abort the procedure.

Thanks again,
MJ

P.S. Actually, what I mean by abort is to start over with boolits I cast from my 180-LFN at BHN 11 and sized to approx. .311".

[Bass Ackward]

I just measured my fired cases in my Remington 06 @ .316.

And I shoot .3095 in a freebore section that is .310. And that works for sub MOA up to 2600 fps.

I put that in there because I think it is necessary when a person gets too focused on one specific problem variable for accuracy. And sometimes that one area ISN'T the reason.

I have seated bullets with the entire bearing area in the neck making jump to the rifling over .200. The slop in the neck "on this gun" was NOT a negative as the neck itself was still centered by the taper on my cases. My dies were doing nothing to ruin this concentric condition that occurs once brass is fire formed. With centered defined as not negatively impacting accuracy.

Remember, that is on "this gun".

[BABore]

BABore, if you made a formalized version of that and posted it somewhere I'd sure clamor to the mods to make it a sticky, your advice on firelapping saved me a ton of money, time, and kept me from screwing it up. I've revived three great old rifles using your method.

Gear

This is like the third time I've posted the technique. Each time I condense it a bit more. Sooner or later I'm just going to do what most of the old farts do here. Tell em to go search for it.:groner:

[BABore]

Thanks for the tips Bruce. It's too late on the not sizing part though. I've already got 25 rounds loaded up for tomorrow but the only sizing was with a Lee Collet Sizer that provided just enough tension on most case necks to hold the 320 grit boolits in place. Most of the necks wouldn't even touch the sizer on my 31 M-Die. Some of the boolits provided a bit of resistance though when seating. These boolits were from Beartooth and specifically for fire lapping; i.e., BHN 12. I ran them though my .310" 450 die (normally sizes normal boolits to .3105") to true them up a bit and most of them 'miked' around .311" after rolling them in the grit. Few of them are round though which kinda makes me a bit nervous. I didn't fill the grooves with lapping compound so maybe I won't have too much of a blow back issue. The neck area in this particular '06 is so wide that a .314" boolit will drop inside a fired case.

There's some strange tooling-**** (I guess) going on near the muzzle of this rifle and after firing 3, 5-round strings I don't notice any difference, I'm going to abort the procedure.

Thanks again,
MJ

P.S. Actually, what I mean by abort is to start over with boolits I cast from my 180-LFN at BHN 11 and sized to approx. .311".

Don't abort yet and you probably shouldn't have sized the boolits to begin with. The firelapping process works progressively from breech to muzzle. That's why it creates a tapered bore. The boolit works the breech end first and gets sized down by any constrictions or rough spots. The rest of the bbl doesn't get worked much. Each successive lapping boolit goes a bit further down. You will not see the muzzle tooling marks to start getting burnished til the end of the process. That's why you have to pay attention and stop when you just start to see some action there.

[geargnasher]

It was explained to me that the abrasive in the Clover compound doesn't actually wear, but breaks up in to smaller and smaller pieces under pressure which makes it always cut more for the first part of the barrel. The stuff is crushed so fine after a few inches that it isn't removing much metal, so the first 10-15 shots don't do squat to the muzzle end.

I watched the muzzle closely after each 5-round shoot-clean series, all of a sudden I could see the clean metal approching the muzzle within 1/2" or so. Two more shots did it, then the tight patch trick to finish.

Gear

[Marlin Junky]

I only shot 10 rounds this morning 'cause I stuck 5 of them (3.0 grains of 453/154 grain LBT) near the muzzle. Fortunately, a friend was able to loan me a solid brass rod to shove them out. Anyway, the compound remaining on the boolits was so fine it felt and looked more like graphite than lapping compound.

Addendum:

I've shot a total of 12 or 13 lapping boolits through my M70 and scrubbed the hell out of it with JB and tonight noticed funny pot marked looking patches near the muzzle while shinning a flashlight inside. I thought to myself, there's no way lead fouling could survive what I've done today so I fetched a toothpick and started rubbing over the areas while looking through a 5X lens. Sure enough, the areas felt rough. I figured, if I can feel the roughness with a toothpick, there's no way I'll be able to lap it out. Then I pulled a .358 Ruger stainless M77 out of the rack and examined the muzzle area with my 5X lens... the interior surface (mostly the top of the lands) looked like a wood rasp. What is up with these barrels? I'm starting to understand why serious shooters elect to install custom aftermarket barrels on their rifles. Regarding the M70 '06, I'm going to re-try a couple of my more successful loads to see if there's an improvement in accuracy (or more dependable accuracy) and if not, I may cast up a bunch of soft (Pb/WW) LBT 180 LFN's (.311+") and return to fire lapping (at least I know 3.0 grains of 453 is not enough and 4.0 grains is too much!). I'm not very optimistic though because if there are "pockets" traversing the barrel for lead to accumulate, I seriously doubt this barrel will sustain any decent level of accuracy beyond about 1800 fps. The question I have now is: will my .30 cal boolit molds be of any use to this rifle after I'm finished fire lapping out the gross imperfections or will I need to treat this rifle as a .303 British? I have been wanting to give Lee c312-185 a whirl. :lol:

MJ

[Marlin Junky]

In a related topic... what does a neglected bore look like that has had a few surplus rounds with corrosive primers shot through it? I've never fired a round of anything with corrosive primers; however, it wouldn't surprise me if the previous owner of my '06 did and then failed to clean it.

MJ