[pistolpete]

I recently talked to some guys at a local gunshop about this topic and they said that using JB bore paste or IOSSO bore cleaner with nylon brushes or tight fitting patches would do the same thing as firelapping. Any thoughts on this would be appreciated.                          Pistolpete          

 

[Marshall Stanton]

PistolPete

Very respectfully, I will have to strongly rebuke that notion!  As far as polishing a bore, yes, what they say and recommend will do wonders to slick up a bore, and put a nice high gloss finish on the interior of a barrel.  But to do the same job as fire-lapping, I'm afraid not... not at all!

Just consicer for a moment that they are advocating a springy brush wrapped with some type of cloth or patch impregnated with the JB paste.  This spongy affair will follow every contour of the barrel uniformly, cpmpressing where necessary and expanding where possible, exerting pretty much uniform pressure throughout the bore.  

Now, let us look at fire-lapping.   We use a BHN 11-12 oversize bullet with lots of bearing surface impregnated with a lapping compound.  When that bullet goes through a tight spot (such as under dovetail sights and where the barrel shank screws into the frame on revolvers), it is swaged down, and then puts very little pressure, proportionately on the rest of the barrel during its passage to the muzzle.  Consequently the most aggresive lapping action is at the constriction.  This process continues as lapping bullets are fired through the barrel (at airgun velocities) until such time that uniformity of barrel diameter is acheived.

There is no way on earth that the tightly patched brush with JB paste can accomplish this task.   It positively will not remove tight spots in a barrel!  It does have its place, to be sure, but not in place of lapping where there are tight constrictions in the bore of a firearm.

I hope this helps clear up the question, and put some more light on the lapping process!

God Bless,

Marshall

 

[pistolpete]

Thanks Marshall, I couldn't ask for a better response! Pistolpete      

 

[Clark1]

As part of a bluing vs surface finsish experement last week, I put a barrel in the lathe and:
1) I turned it a 3600 rpm.
2) Polished with gray Scotch Brite
3) polished with brown Scotch Brite.
4) Followed with green
5) Followed with white
6) Followed with a rag and No. 7 auto Rubbing Compound
7) Followed with a rag and JB Bore paste

I used a microscope to examine after every step. The JB is an extremely fine pollish.

I know someone who swears by firelapping new Savage rifles with JB on copper jacketed bullets at full velocity. He claims that they usually come down from 1.5" to .5" groups in 20 rounds.

I know another guy with a Russian M91/30 Moisin Nagant WW2 surplus rifle. The bore looks terrible. It shoots consistant sub MOA at 100 yards [I have seen this done]. He says he hand lapped the rifle by pouring in the hot lead on a cleaning jag ect. He said there was a tight spot. He concentrated on the tight spot until it was gone. He used valve grinding compound. [Clover Brand].

I know another guy who is a gunsmith to benchrest compeditors. He says that fire lapping is better than hand lapping, because the barrel is ususally worse off after an amauteur hand lapp, and no worse after a fire lapp.

 

[moose]

Having hand lapped rifle and pistol barrels on a production basis until my arms were so big I couldn't button a shirt, don't waste your time hand lapping. Fire lapping will produce a superior finish and end result. I've fire lapped a couple  of dozen guns with wonderful results! How about a Single Six that was shortened by some idiot and crowned on a buffing wheel as best I could tell. When I started shooting this revolver it shot way high and about 4 inch groups at 30 feet in my shop. Fire lapping with 22 cb caps dipped in lapping stuff the groups began shrinking with each cylinder full and moving to the sights. After FOUR cylinders full( 24 shots) the gun was fixed except for some much needed cosmetic work. Fire lapping works very well on revolvers. Good Luck

 

[James Gates]

As one who hand lapped barrels for many years with a poured lead slug and abrasive, I have given a lot of thought to fire lapping.It appears that the concept of lapping barrels to remove costrictions fall into two camps..fire-lapping and hand-lapping. Some confusion still exists on the difference in removing constrictions and the other, polishing (smoothing) out the barrel. They are not the same. As Marshell says, JB on a brush or tight patch will not remove constrictions...period! That method, using JB, does wonders to remove both lead and copper fouling, nothing more! On the other hand..Hand lapping with a lead slug, if done properly, will remove constrictions and has been used for generations. However, as barrel steels have become more resistant to abrasives, I feel that done properly, fire-lapping removes some of the human error! Do I fire-lap....No, not yet!
Best Regards, James

(Edited by James Gates at 3:32 pm on April 28, 2001)

 

[DOK]

What do you folks think about Taylor Throating as a fix for the constriction where the  barrel shank screws into the frame on revolvers?

Respectfully,

 

[Southpaw]

I'm almost embarassed to pose this hypothesis, but I have to anyway.  Most gun shops that I've talked to, and sites that I've read, say that after a so many rounds (and the number varies) barrel constrictions are removed and accuracy improves.  That being the case, I pose two possibilities (mainly because I own an RB and slugging the barrel is near to impossible because of the Compensator):
 1.) Fire about 200 rounds of JHP's, and then hand lap the bore to polish and smooth the groove area.
 2.) put some lapping compound on the JHP's and fire them at about 840 fps (this can be done according to Casull).
Now, once step #1, or #2, is accomplished, slug the cylinder end of the barrel to determine the diameter bullet desired (this is one of the two measurements that Veral Smith required to determine the size of the mold to make, that and from the crown end).
Am I nuts?  Tell me why, please!

God bless,

 

[MikeG]

Yes, enough jacketed bullets and the barrel smooths up, that's well known.  But why would you want to lap with jacketed bullets?

Anyway, since you are having trouble slugging the bore, here's a suggestion.  Just measure the chamber throats, and order bullets slightly smaller.  Say they're .431", for example, then just order bullets at .430" or .4305".  Try them out and see if you get the results you want.  If so, you're done.

The cylinder throats obviously limit what bullet size you can use.  It won't hurt for a lead bullet to be 0.001" or 0.002" larger than the groove diameter.  If you don't know the exact groove diameter you can still make some intelligent choices based on the cylinder throat size.

Make sense?  

 

[Southpaw]

MikeG, Thanks.  That's a good suggestion.  About the lapping compound on jacketed bullets, I've read about the practice on one or two benchrest sites, apparently that's not as uncommon as you might expect.  I know at high velocities you can permanently weaken the barrel at the forcing cone, but you can do that using cast bullets, too.  I know from FA's site that I can get the velocity of a 240gr JHP down to about 800 fps.  My thought with the lapping compound was that scratches or small tool marks would be removed rather than just filled in with copper from the jacket.  Also, I can use .451 diameter bullet that won't open it up too wide.
Thanks again.  If you get time, I like to know what you think of my rational... and anyone else out there, too.

God bless,

 

[Jack Monteith]

Hi, Southpaw:
  HOLD IT!  You'll just cut your lands down if you use an undersized bullet. If you've got a constriction, you've got to cut the bottom of the grooves too. Read Marshall's post again. Better yet, get his book.

Bye
Jack  

 

[Southpaw]

Jack, thanks for the caution.  I do have Marshal's book, though, and have read the sections on barrel slugging and fire-lapping at least a half a dozen times (and I think that's a conservative estimate).  However, a .451 JHP is not undersized for a 454.  Nosler and Speer both post a .451 diameter, while Sierra posts a .4515 diameter, for jacketed bullets.  Of course, from a company like Beartooth we are fortunate in that we can get cast bullets in varying diameters.  As far as bore lapping goes, there a number of methods lapping bores.  I'm trying to gather info from sites and forums that I feel have demonstrated technical abilities. This forum, in my book, is definitely one of them, but not the only one.  So when views differ among people whose knowledge and competence I respect, I have to ask why. Before any damage is done.
Thanks again.

God bless,

 

[5 Shot]

Southpaw,

Just because the jacketed bullet makers only list bullets with a 0.451 diameter does not mean that it is a correct bullet/bore fit for your revolver.  Most Casull revolvers have a 0.4515 or larger bore.  That is why you should slug the barrel and use a lead lapping slug that is slightly larger than your ACTUAL groove diameter.  It would be a shame to destroy the rifling using undersized jacketed bullets (once the lands are lapped down they can't be restored).

Good luck.

 

[MikeG]

Whether the jacketed bullets are correctly sized (or not) is not the entire problem.

A jacketed bullet or even an overly hard lead bullet can be a little 'springy' (for lack of a better term), and follow the contour of the bore.  That's about the last thing that you want when lapping to remove the 'choke' under the barrel threads!

If the benchrest shooters lap with jacketed bullets, you can be sure they have a very good reason to do so.  But - they are not trying to solve the same problem.  Their barrels are so much smoother and uniform than the average handgun barrel that there is really no comparison.

I'd advise sticking with lead bullets.  That way you'll know there will be no problem.  Have you measured the chamber throats yet?  I'm curious what the diameters are.

 

[Jack Monteith]

Hi, Southpaw:
  5 Shot is right, your barrel may larger than the commercial jacketed bullets. I've lapped two barrels with Marshall's supplies. One was a new rifle that is now cured of a horrible case of copper fouling. The other is an oldie that needs another 20 or 40 rounds, but is better than it was. I was not aware of the Neco process (using jacketed bullets) when I did the new rifle about 6 years ago.

  You could check the bullets you've got on hand by firing a light load into wetpack or water and seeing if it's getting to the bottom of the grooves. It's easy to see if it's still shiny between the land marks.  It's probably more accurate than trying to measure a slug from a 5 groove barrel (S&W or Lee-Enfield) without the special V block normally used.

  I saw a picture of someone, probably Seyfried or Venturino, slugging a barrel from the rear. He put the centre of a long steel bar against the slug, held one end by hand and hammered the other end.  More likely, he had the slug as close to the hammer end as possible.  Anyone remember that article?

  I don't blame you for being cautious and I don't doubt that some barrels have been damaged by firelapping. Whether it's operation error or a cranky barrel is a good question. Precision Shooting Magazine gave the Neco system some pretty favourable coverage a while back and the benchrest crowd would have panned it pretty quick if it didn't work. (I dropped my subscription when the international mailing rate went through the roof.) However, these guys aren't shooting revolvers. The top grade benchrest barrels are better left alone but some production varmint barrels need help. A rifle barrel can't have a thread choke because the chamber extends past the action and most varmint barrels don't have dovetail cuts. So these barrels are pretty uniform in diameter but a bit rough and the Neco system must do a good job of slicking them up. Also the jacketed bullet spring back that Marshall refers to isn't a problem if the barrel has a constant diameter.

  If we have a serious constriction, we don't want any spring back. The other problem I see is that we may not get the constriction cut out before we move to the finer grits, which won't cut it out. So we should slug after every 20 shots and see what's happening. I've read comments from two of the top barrel makers, Gale McMillan and Dan Lilja, who strongly object to the extermely fine 800 and 1200 grits.

  There's another problem with a minimum sized bullet. Suppose we have an .001 constriction. Cut it out and we're trying to lap with an undersized bullet, and just washing out the lands.

  Hand lapping is fine for people like Mr. Gates who have their technique down pat. I think firelapping is a better choice if we don't have an old hand looking over our shoulder on our first attempt.

  New production (not custom) chrome-moly barrels are blued on the inside. I've only seen one article on this, but the author claimed they won't shoot until the blue is out. He said you can shoot it out with 200 rounds or scrub it out with JB (best) or use blue remover (tricky). He used wood plugs in the Thirties, but now uses teflon washers to seal the bore, and claims they break in a lot faster.

  Anyhow, I'd run at least 200 jacketed bullet through it before lapping unless it's fouling something terrible. It may not need lapping at all.

Bye
Jack

 

[Southpaw]

Jack, 5 shot and MikeG, thanks.  I appreciate all the help and info.  I already have the sinkers from Marshall, so I plan to slug the throats and attempt to slug the bore from the rear.   I did it once before with a 44 mag, but wasn't very satisfied with my results. By the way, Jack, I found NECO's site where the discuss what they refer to as 'pressure (fire) lapping'.  They do recommend cast bullets for lapping revolvers, restricting jacketed to rifles. It was interesting to read even though it didn't say to much about their process, just some testing results.  Anyway,If you're interested in reading what they had to say try 'www.neconos.com/details2.htm'.  Guys, I really appreciate all your help and time.  Your part of what makes this forum so great.  Thanks.

God bless,

 

[James Gates]

Greetings Everybody....This has been an interesting and very informative series of posts! These are the "how to" posts that are needed! Now, with that said......Please remember that I do not suggest that hand lapping is for eveyone! I said that I feel fire lapping might be the answer for removing constrictions in barrels using hard cast bullets. If the shooter is using jacketed bullets he may be better off firing a couple hundred rounds of jacketed bullets, as suggested, before he does anything. At that point, if he is still getting copper fouling, I suggest no grit more abrasive that the combo of jewelers rouge #1 and Flitz. In fact, he would be better off using the jr#1/Flitz by cleaning the barrel with it after aboit 20 rounds of shots during barrel break in. We must be clear in our minds the difference in fire lapping for constrictions and using something to smooth out the surface of barrels. I do think that has been covered well by these posts.
I do want to point out one thing about a jacketed bullet that is a few thousandths undersize. Unless the presure is very low...these bullets do bump up to fill the lands and grooves. However that is not to suggest their use in fire lapping!!!!!
Speaking quite frankly...I see no real use in fire lapping or handlapping, in most cases, a barrel for use with Jacketed bullets alone. I do suggest the smoothing out with jr#1/Flitz during breakin and to clean out copper.
My concern is that one might do too much of a good thing! Ues the old saying.."make haste slowly" when it comes to working on a barrel. Buy Marshall's complete firelapping kit and follow instruction to the letter!
Best Regards To All, James

 

[Southpaw]

James, thanks.  Question 1: can you tell me where I can get jr #1 and Flitz?  Question 2: Am I correct with the following assumptions?  For myself, I plan on using a combo of cast and jacketed.   If I understood Jack's post, I could still shoot a few hundred rounds of jacketed initially; then shoot a mix of jacketed and cast.   If accuracy is where I expect it to be and if I don't have problems with leading or copper fouling, then no need to do lapping.  Thanks again James and everyone.

God bless,

 

[Jack Monteith]

Good Afternoon, Gents:
  I'd lap a barrel (either way) if accuracy is falling off in less than 20 rounds and lapping is the only cure if you're seeing pressure signs in less than 20 rounds. Otherwise, you're in for a lot of polishing.

  It took about 60 rounds for copper fouling to drop to a negligible level after lapping the new rifle. So, barring a noticable contriction, I'd recommend at least that many jacketed bullets between each 20 round lapping session.

  Neither of my guns that I mix jacketed and lead in are bad for fouling.  I understand that lead on top of copper is a bearcat to clean out, but a lot of people claim they fire a few jacketed bullets to clean out the lead at the end of a session. Any comments?

  Yup, Southpaw, fire a hundred or two jacketed bullets, clean out the copper and try some lead bullets.  If she shoots straight and doesn't lead, you're home standing up.

  Just remember, soft bullets for subsonic loads and hard bullets for magnum loads; and if your cylinder throats are smaller than than your groove diameter, she'll lead no matter what shape the barrel is in.

  One other point. Never mix brands of gun cleaners. Sweet's and Shooter's Choice is a particulary noxious brew.

Bye
Jack  

 

[James Gates]

Southpaw..Jack's correct about jacketed bullets. The entire thing is just a matter of opinion as to which to do first....lap or polish. I polish first and then decide if I need to lap. Sometimes I do need to lap, sometimes not, depending on the quality of the barrel and what it screwed into. My first concern has always to get the barrel smooth out to reduce copper and/or lead fouling. here again it's just a matter of whether to skin a cat from to front or back.
Now..On this notion that shooting jacketed bullets to clean out lead. This can work either good or bad! If the barrel is leaded bad and a jacketed bullet with an ogive is fired in it....a certian amount of the leading is over-road which in turn can cause the very problem you would firelap to remove. However, if the jacketed bullet has a sharp flat base..then load a few rounds with reduced charge and load the bullet in point down. These will scrape out the most severe leaded barrels.
As for Flitz...It can be bought on the web. Marshall post a supplier of abrasives, but I don't remember the name. When all else fails...go to an automotive supply house and buy a stick of "Dico". Use a corse file and make your JR1 dust. Mix about half and half, put it in a shoe ploish car for keeping. A little goes a long way. Remember..all these procedures are aimed at the same problem...just which to do first is an opinion. If you do fire lap, you still should breakin the barrel.
Best Regards, James