Fire Lapping ??

[BABore]

A few weeks back I had a post on the woes of my Winchester Model 70 Super Grade in 300 Win Mag. I have since tried just about everything to make it shoot. The last groups, (3) 3-shot at 100 yards, averaged 1 5/8". One of the replys, to my original post, mentioned the throat condition. Not knowing exactly what to look for, I compared it to a custom Encore barrel that I have. It's hard to tell for sure, due to looking through the action, but the throat does appear rough. I also have to seat the bullets way out to be 0.010 off the lands. So as a last resort to rebarreling I'm thinking of fire lapping the barrel. It will only cost about $25 so what the heck. I'm looking at the David Tubb kit that has the bullets precoated. Does anybody have any experience fire lapping. I read an article by Rick Jamison, in Shooting Times, that gave some results.

[Mikey]

BABore:  it works!  I've just finished lapping a Winchester 94AE in 444, and the process works.  My groups shrunk to about half of what they were before lapping, and my shooting was at 100 yds with open Winchester sights and 58 yr. old eyes.  Also, during the process of lapping I was able to recover a bunch of fired slugs and knew about which order they were fired in.

I test fired a gas checked slug first for some indication of what markings the rifling might impart, then repeated that process after each 6 lapping rounds. All in all I fired 30 rounds during the lapping process before I hand polished the bore.  You could definately see the difference at each stage in the process, to the point where the last gas checked rounds I fired for barrel markings showed that the rough edges were definately gone.  It was a fun process and it works.  HTH and have fun.  Mikey.

[haroldclark]

You bet it works.  I have a new 30-30 Thompson Contender barrel and a new to me 7mm TCU barrel just waiting for a range day.  I have 66 fire lapping loads ready for each of them.

I use LBT (Veral Smith) lapping compound and have for 20 years.  

I have had a great deal of experience with the lapping and most recently had the most dramatic difference I have ever seen.

My buddy has a new 14" barrel replacement from Thompson Center.  As new, it would not hit a pickup truck at 500 meters (547 yards).  I made up the fire lapping bullets and we fired 50 rounds.  It improved, but he still couldn't hit a Ram at 500.

We fired another 45 lapping loads.  The next range session he fouled the bore with 20 rounds of jacketed bullets and then we went for the 500 meter rams.  Got them every time.  Then we went to head shooting the rams and got them too.

I firelapped a Siamese Mauser in 45-70 a few years back.  It would shoot no less than a 12" group at 200 meters.  After firelapping, I tested it with cast bullets and then it would shoot 4" groups at 200 Meters.

I don't own a gun that I haven't firelapped and I own a bunch.  I have a Sig Sauer 229 in 9mm that will not shoot less than a 5" group at 25 yards.  It is next.

I have two S&W revolvers that were built when the Arabs owned S&W.  The barrels were screwed into the fram so tight that it reduced interior dimensions at the frame.  This did not lend to accurcy, I must say.

One day, I figured I had nothing to lose and I firelapped the 357 Model 686.  Steel sparks and debri flew.  My shooting buddy moved down range to get away from the shrapnel.  Now, the 686 shoots great.

Well, now, my beloved 624 in 44 Special had the same issue.  Same game and same results.

I could go on, but suffice it to say that fire lapping works.

Look for Lead Bullet Technology on the internet.  He has a $25 book in which he details firelapping.

Harold Clark

[gunnut69]

Fire lapping does smooth the throat of a barrel, it does this by wearing away some of the metal.  This erosion takes place in a decreasing ratio of effctiveness.  That is the throat is cut the most and as the bullet proceeds down the bore the cutting action decreases.  It will move your throat further from the case, not closer.  It can be helpful and does smooth things up but it can also lead to premature wear on the throat.  Eyeballing the throat of a modern rifle will not allow a reasonable estimation of throat or bore condition.  It is not a cure all and I would strongly advise consulting a smith or better yet, if this is a new weapon a call to Winchester is in order.  If you do decide to proceed do so cautiously.  It is possible to firelap a barrel, to death...

[Doctor Sam]

Three, three shot groups within 1 5/8" is certainly within "minute of deer" accuracy as far out as you need to shoot even with your 300 Magnum.  I assume this is from a solid rest such as a bench on a known range.  Let me ask this: what can you do standing on your hind legs with three shots from your 300 Magnum rifle?  What can you do with three shots after sprinting uphill for 125 yards, then having to shoot downhill at a swiftly running deer/elk/moose/sheep etc.  Would that rifle shooting 1/2 the group it now shoots improve your shooting?
The average hunter who owns one rifle, takes it out to the range before the season and sights it in from the bench couldn't put three out of five rounds in a 9" pie plate at a hundred yards after doing any of the above.  We need to view these things in the real world.  I suspect that 1/2 of 1 5/8" isn't going to make much difference in the long run.
Doctor Sam

[BABore]

Dr Sam,

I don't just own one deer rifle, but many. I probably shoot more rounds off hand than most shoot from the bench. I shoot NRA handgun silhoutte AA class, high power, and bullseye pistol. My bench is custom made with tripod rest and bags. If you had followed my previous posts you would have noted that this was a problem rifle. Groups vary in size and position. That 1 5/8" group average was comprised of (3) 3-shot groups of 1.00", 2.02", and 1.88". They walked around the bullseye from 3" left to 2" right, to 1 1/2" high. Hot or cold, first shot or last shot, there's not real pattern. You are right about practical accuracy though. If this rifle would consistently group around 1 1/2" it would probably be fine. All of my other rifles will shoot 1 1/4" or less with no wandering. I much prefer my rifles to shoot minute of angle from a solid rest.

[gunnut69]

I'm sorry as I also missed the wandering groups thing.  Wondering zero will NOT be cured by firelapping.  It is sometimes helpful with overly large groups but if they are moving about the paper I would guess a bedding problem, action screws bottoming out, a loose scope(either the mounts or the guts), and if using handloads it is possibley an out of square bolt face..  Poor grouping is much different than groups that move about the paper.  Tried a different scope?

[BABore]

To answer some already posted question, here is the start of my original post listed in Bolt Action Rifles under Win Mod 70 300 Mag Woes.


I need some ideas or help on a Winchester Model 70 Super Grade in 300 Win Mag. I bought the gun about 5 years ago for $300. Figured it was a steal. Now I'm not so sure. I'll give a brief history of my struggle.

- Overall the gun was in good shape 95%
- Barrel had a lot of copper fouling. After days of hand cleaning gave up and bought a Foul Out system. Took 16 hours to get to bare metal. Lots of copper and powder fouling, just a touch of rust between layers. Cleaned bore was not pitted, good throat, factory rough.
- Worked up starting loads with new brass. Tried (3) different 180 gr bullets and (3) suitable powders for (9) different loads. All brass was sized, trimmed, deburred at both ends, then segregated by weight +/- 2 grs. Bullets seated 0.010 off lands with Stoney Point gauge. Throat seems pretty long.
- Shot (3) 3-shot groups with each load. Showed some bullet/powder preference, but groups were'nt consistent in size, shape or placement. Shrugged it off to small sample size. Necked sized fired brass and reloaded with most promising combinations. Loaded (9) rounds of each load, increased powder in 1 gr increments til book max.
- Again shot (3) 3-shot groups with each set. Found max charge with each set. Groups showed some charge weight preference, but again had small group followed by a large one followed by a small one. Hot barrel or cold barrel didn't show a pattern. Noted a tight group with the next stringing horizontal or vertical.
- Went home ticked. Looked at bedding/stock pressure. Found factory bedding at recoil lug was causing pressure on one side of barrel. Barreled action was twisted in the stock.
- Fitted the stock with brass pillars. fully bedded action and barrel channel. Free floated barrel.
- Best loads shot better, but still no consistent grouping.
- Added 6 lb pressure point in forend. Same thing.
- Fully bedded barrel. Same thing.
- My latest set of (3) shot groups were as follows
1.00" stringing vertical
2.25" stringing horizontally
3.50" nice large triangle
1.50" triangle with horizontal stringing.
Groups showed a tendency to walk around the bullseye. Some on the mark, some right, some left.
- In all of my shooting the barrel was cleaned every 12 shots, then a couple of foulers. Always watched the barrel temp.

- The muzzle crown looks fine, but hasn't been redone. The case neck runout, on a fired case is +/-0.0005.
- My limited experience says bedding problems or something else flexing. Have tried (3) scopes and (2) mount/ring setups.
- Would like to see if I can make this rifle shoot before I go to the expense of a new barrel and action blueprinting.

Please help, I'm running out of ideas. Might check the lug engagement tonite. Never done this before. If the contact is limited, How do you lap the lugs?

Since that post I did check the lug engagment. It's ok. I also fully bedded the barrel. Finally I just got done fire lapping the bore this weekend. I still have to try out my best loads again. After lapping the throat moved out 0.0530 inches and cleaning is much easier. I could feel the difference and the first 30 rnds of the Final Finish kit.

[John Traveler]

BA Bore,

If you really spent 16 hours electrolytically cleaning your barrel down to "bare metal", you have part of the answer to your accuracy problems.

Copper fouling does not "rust between layers".  Steel rusts.

Despite the advertisement claims, electrolytic cleaning and ammonia or acid-based solution DOES remove steel from the bore.  For a normal 10-15 minute cleaning, the iron removal is insignificant and can't be measured using home shop equipment.  However, several or many hours of this treatment is another story.  You have bore damage.

You've probably enlarged the bore/groove diameters enough that standard .308" bullets don't fit properly.  Additional fouling will result from shooting.  Without precision air gage equipment you won't know.

The bore smoothness after you fire-lapped tells the other part of the story.  It's smoother because the abrasive charged slug removed more steel.

I dunno how you are gonna getter better accuracy without a new barrel.

HTH
John

[BABore]

John,

When I got done manually cleaning the bore with solvents, Copper Out, and J-B, I could see a copper sheen to the entire bore. That's when I decided to try the Foul Out System. After removing the solvents with alcohol I hooked it up and it pegged the meter. After running for and hour, it stopped showing improvement. According to the instructions, I probably had a layer of powder fouling. The barrel was emptied and cleaned with solvent, then set up again. This procedure was done several times to remove all the copper fouling. The Foul Out rod was completely covered with copper until the last two runs. The rust showed up after the 2nd or 3rd cleaning. It was between layers of copper/powder fouling. At no time was the Foul Out system left on continuously for more than 2 hours. Now other rifles that I use this on take 15 -45 minute, in one run. Of course I clean my guns every 15-20 rnds when shooting, and a thorough cleaning once I'm home. This Winchester was a used gun that I was mainly picking up for the action and stock. I figured that $300 for a Super Grade wasn't bad even if I couldn't make it shoot. It's been kind of a project gun. If I can't make it shoot to my satisfaction, it will soon be a 375 H&H or 375 Ultra.