Firelapping, holy crap it works or how I saved $300

[akajun]

So long story short I traded for a Howa in 223 a year ago. Gun had a few problems I could see right off primarily that it fit poorly in the Boyd’s stock it was in. A few months of tinkering in my spare time ended up with it pillar bedded and free floated but it still would not shoot better than 2”@ 100. Bore seemed good and checking the throat with a Stoney point gauge showed a fairly new barrel. Looking down the bore it seemed to be ok.
When I finally got a bore scope it showed why, the bore from the throat to about halfway down showed small bits of random clusters of pits . I’ve never seen anything like it , I’ve seen full on pitted bores from poor cleaning, corrosive ammo, etc but not like this. Anyway the pitting was causing extreme smearing and fouling just as random as the pitting. Scrubbing with JB paste removed the fouling, but not the pitting.
Figuring I had nothing to loose I made up 30 lapping bullets from 220 , 320, and 600 grit compound by pressing/ rolling them between two mild steel plates.
Loading them up in old brass I went to the range and began firing away. The procedure I used was a super clean bore. Fire five shots, clean, fire five more, clean, etc. in total I fired 10 of each grit.
I then cleaned the bore really well and began firing. i started with American eagle 55gr fmj, while a little wild at first it printed a 1.5” group for its first 5 rd group but the flyers being the first two shots I fired another one which was slightly under 1”.
Next I fired 4 five shot groups with federal 55gr trophy bonded bear claw. Three were 3/4” and one 1/2” group. I’m very pleased.
Some things to contemplate if you consider doing this yourself.
Use loads on the bottom end of velocity, I used 25gr of Varget simply because my Dillon was already set up for it. I had a few popped out primers and hard extractions. I probably should have used 23gr.
Two wipe your cleaning rod off each time you pull it back, even when brushing, I felt grit each stroke.

 

[Dusty Stevens]

So if the pits were .005 deep is your barrel .005 larger now?

 

[BoydAllen]

I did a much less extensive experiment on a NOS 03-A3 barrel that was cut rifled. Under close inspection the tops of the lands looked like micro acme threads. After firing, looking from the muzzle, the copper on all of the lands disappeared into the darkness. There was no way that I could remove reamer marks that were that deep, but after a crude fire lapping, the fouling was much improved. My conclusion was that one does not need to remove the teeth from the file, merely dull them sufficiently, take the corners off so to speak. I don't mess around with rough barrels at all these days, but my one experiment with fire lapping was a qualified success, given what I had to work with.

 

[akajun]

I did a much less extensive experiment on a NOS 30-A3 barrel that was cut rifled. Under close inspection the tops of the lands looked like micro acme threads. After firing, looking from the muzzle, the copper on all of the lands disappeared into the darkness. There was no way that I could remove reamer marks that were that deep, but after a crude fire lapping, the fouling was much improved. My conclusion was that one does not need to remove the teeth from the file, merely dull them sufficiently, take the corners off so to speak. I don't mess around with rough barrels at all these days, but my one experiment with fire lapping was a qualified success, given what I had to work with.

Yeah I kinda figured that's what it did, now way I was gonna fully remove the pits but rather just knock the sharp edges off, smooth it out, and maybe give the barrel a little "choke" or taper. Dusty I haven't had a chance to borescope it or measure it with a stoney point gauge or soft lead slugs yet to see what it did to the throat area or bore diameter. I dont expect to win F class matches with it, this rifle's primary purpose will be for training new shooters and shooting hogs. I didn't want to spend the time and money on a new barrel if I didn't have to and had nothing to loose because if it didn't work I was right back where I was. Just putting this info out there for anyone who may be in a similar situation.

 

[hunter67]

I have used this system on two hunting rifles that people sold cause they just wouldn't shoot. I shot 3 coarse, 5 medium and 8 fine with cleaning in between. Viola gun shoots. I'm not a bench guy just a hunter but it is a tool to at least get a rifle usable for hunting. Of course that is after doing all the normal stuff first.

 

[geo.ulrich]

So if the pits were .005 deep is your barrel .005 larger now?

.010 bigger .005 per side

 

[Mark W]

Maybe I should try fire lapping this howa. The whole length of the barrel looks like these pics. I always wondered why it coppered so bad and wouldn’t consistently hit a paper plate at 100 yards....lol.

 

[butchlambert]

Maybe I should try fire lapping this howa. The whole length of the barrel looks like these pics. I always wondered why it coppered so bad and wouldn’t consistently hit a paper plate at 100 yards....lol.

I don't think it will help hitting the plate.

 

[Straightshooter1]

It wasn't long after I got my Gen2 RPR .308 that I decided to see what improvement I might get with firelapping. So, I purchased Tubb's Final Finish Bore Lapping System containing 50 bullets and proceeded to firelap the barrel following the instructions that came with the package. The package came with 5 different grits (10 bullets per grit) and you start with the coarsest one and finish up with the finest one. It says it's not supposed to remove more than .0003 from the surface. Anyhow, I decided not to use the 2 coarsest grits as I felt, at the time, the barrel was new enough and didn't really have any big issues other than being a mass produced factory hammer forged barrel. The gun was consistently shooting close to .5 MOA with hand loads before and with the firelapping done, that came down to below .5 MOA, right at .4 MOA (sometimes a little lower, sometimes a little higher). So, that was a plus. But, in addition to that when I would clean the barrel, it's was easier cleaning, like a LOT easier push patches down the barrel and it didn't foul as much as before (another +). The biggest negative for me was that when I took a measurement, my lands was about .011 deeper. Other than the latter, I was quite please with the results and would do it again depending on the issue . . . though I'd never do this with a high end barrel.

 

[akajun]

Maybe I should try fire lapping this howa. The whole length of the barrel looks like these pics. I always wondered why it coppered so bad and wouldn’t consistently hit a paper plate at 100 yards....lol.

Go for it you’ve got nothing to loose

 

[Stan Taylor]

Maybe I should try fire lapping this howa. The whole length of the barrel looks like these pics. I always wondered why it coppered so bad and wouldn’t consistently hit a paper plate at 100 yards....lol.

You can also send it to me an put a good barrel on it that you won't have to fire lap.

 

[Dusty Stevens]

You can also send it to me an put a good barrel on it that you won't have to fire lap.

^^ exactly. Best money youll spend on it

 

[gunsandgunsmithing]

It's been a while but I recall doing 6 factory barrels this way over a period of a few years. I consider it a last resort option!
It did help 3 of the six, one a fair amount but I don't remember exact numbers. Two it helped marginally. One it made very little difference on and the other two got a lot worse!
All smoothed up when pushing a patch through and all had measurable advancement of the throat. If ya know the barrel is otherwise toast, it can be worth a try but I would never recommend it for a good barrel. That's just my experience with it.

 

[mchees1]

I have done lapping on a couple of poor shooting factory barrels and it always improved the accuracy and ease of cleaning. I used the Tubb system on my first attempt at fire lapping - really polished up the barrel. The only issue for me was that by using the entire 50 bullet Tubb system, it chased the lands a LONG way down the barrel. Around .080 or .100 if memory serves me. That created a lot more jump to deal with. Since then, I have used the Wheeler Lapping Compound Grit Kit and created my own lapping bullets as akajun described. That way I can decide how coarse of a grit is needed and how many bullets to use. This way I was able to get a marked improvement with minimal land erosion. Just make sure to use a very reduced powder charge due to the increased pressure from bullet friction.

 

[Dusty Stevens]

How about actually hand lapping them? Sending an abrasive bullet careening down the barrel under pressure isnt good. If your barrel is this bad just replace it.

 

[Alex Wheeler]

Dusty is right. Look at the surface of a fired bullet, the pressure and contact areas are not even. The tops of the lands will get the most, then the center of the grooves, and hardly none at the corners of the grooves. Moving throats with abrasive will not maintain that throats geometry, rounds the edges, and absolutely harms accuracy. The throat is the most critical part of the barrel. Pouring a lap is not difficult and teaching yourself to lap is worth while. If the barrel is at its last resort, its a good one to learn on. Gaining knowledge is worth the effort.

 

[hunter67]

Agreed, but don't fire all 50 down the barrel! That is way to much. We all know if you remove to much metal you can't put it back.

 

[butchlambert]

It wasn't long after I got my Gen2 RPR .308 that I decided to see what improvement I might get with firelapping. So, I purchased Tubb's Final Finish Bore Lapping System containing 50 bullets and proceeded to firelap the barrel following the instructions that came with the package. The package came with 5 different grits (10 bullets per grit) and you start with the coarsest one and finish up with the finest one. It says it's not supposed to remove more than .0003 from the surface. Anyhow, I decided not to use the 2 coarsest grits as I felt, at the time, the barrel was new enough and didn't really have any big issues other than being a mass produced factory hammer forged barrel. The gun was consistently shooting close to .5 MOA with hand loads before and with the firelapping done, that came down to below .5 MOA, right at .4 MOA (sometimes a little lower, sometimes a little higher). So, that was a plus. But, in addition to that when I would clean the barrel, it's was easier cleaning, like a LOT easier push patches down the barrel and it didn't foul as much as before (another +). The biggest negative for me was that when I took a measurement, my lands was about .011 deeper. Other than the latter, I was quite please with the results and would do it again depending on the issue . . . though I'd never do this with a high end barrel.

You now have a "smooth bore" barrel.

 

[greisdor]

So now one would have an airgun barrel - ?

 

[AckleymanII]

Years ago, I cast my own 22 caliber bullets to fire lap Rem 700 factory barrels with pure linotype. You can roll the bullets in between two steel plates with the grit you like, bullets have to be sized of course.

I worked up a load with 700X going 1000 fps in 223 and 22/250 barrels.

I ruined the first barrel by firing Ten 600 grit rounds down the barrel. From then on, I used two 600 grit, then up to 10 of the 800 grit rounds followed by 1200 grit rounds. You could feel the barrel getting smoother with a very tight punch type jag/patch.

With my very little experience back then, it was obvious that throats were walking out in a big hurry and bore dia was changing due to velocity dropping.

I made the decision that time invested was not worth it for me....in spades.

At this time, it maybe worth the effort to fire lap some 1200 grit on barrels with heavy fire cracking to smooth the tops of the fire cracks that are curling up, but you know going into it that your efforts are more for fun of "playing". You can know for a fact that the throat dia is much larger that it was when it was new.

A replacement barrel should have already been ordered.

I fire lapped a bunch of 22 Rim fires that I had with great success with all but one Ruger target pistol that I absolutely ruined. I used nothing but Standard velocity cci with 800 grit and 1200 grit. If you go down this road, pick out a "sacrificial lamb" for your learning curve.

Casting a lap would be the way to go, but this does not appeal to many as it is is very labor intensive compared to just sticking bullets in a chamber and pulling the trigger.

Tubb has done extensive testing with fire lapping, his method would be something to investigate. Nathan Foster, the famous goat shooter in New Zealand, has done extensive testing on his big 7mm to smooth out the curls on the fire cracking with good success also. Both Tubb and Foster are dealing with a different issue of fire cracking from extensive shooting, while the OP is dealing with drill marks in a barrel from manufacture.

It is a Hail Mary attempt to try and smooth out the drill marks as there are likely other issues with the barrel as well, but it is fun to play in this hobby.