How to lap a muzzleloader barrel?

[garandsrus]

Hi,

I have a muzzleloader (CVA Optima Magnum - 50 cal in line) that I cast some Lee minne type bullets for. I didn't size them and found that they are a very tight fit in the bore. It was almost like swagging and the bore when I loaded a projectile. I could feel a tight spot in the barrel where the stud was welded on the barrel to attach it to the forend. The force required to get the bullet past the tight spot was at least twice the force to get the bullet to the tight spot. After passing the tight spot, the bullet was very easy to seat the remainder of the way to the powder.

I believe this barrel would be a candidate for lapping the tight spot out to make the barrel more uniform.

Now for the question: How should I lap a muzzle loader barrel? If it was a cartridge rifle, I would just fire lap it. However, with this being a muzzleloader, should I just load it normally with a bullet and lapping compound. This would cause the bullet to shrink to the constriction size before firing.

Another option would be to pull the breech plug and load the bullet and then the powder from the breech, and then tamp the bullet down over the load of powder. This would be fairly time consuming as you can imagine.

A third option would be to put some lapping compound on something (what?) and turn it in the barrel using a hand held drill. This would have the advantage of only working on the constriction since I could mark the rod showing where to start and stop the lapping.

I read the JB firelapping article on CBA site. The JB paste may be the way to go. I could add this after the bullet and powder are seated, which is a fourth option

Any suggestions would be appreciated...

Thanks,
John

[omgb]

I and many others I've known use this technique. By the bore lapping kit from either LBT or Beartooth. Cast some minie's from wheel weights. Following the directions with the lapping kit, load the slugs with compound. Using about 40 grains of 4f, fire a round in a dry, clean barrel. Clean and dry, fire another lapping round, Clean and dry the barrel. Follow this sequence 20-30 times. That will lab the barrel pretty well. Now, using a patch wrapped arond a shotgun cleaning bursh, load the patch with JB bor past and work it in and out of the barrel 100 times. If the patch wears out, load a new one and continue. This will polish the lap job. This made a huge difference in an old messed up GP rifle I had and it cleared the tight spots out of a CVA rifle I had. Accuracy went way up and I was able to shoot ten shot strings without having to clean in between.

[garandsrus]

RJ,

Would this (http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=486249) kit from Midway work OK? It contains multiple lapping grits. I would like to be able to do other rifles also as necessary, including just using the final grit as a "touch up" from time to time, similar to the Tubb Throat Polishing System.

The Beartooth compound only included one grit and didn't mention it's size.

Do you suggest loading the bullets from the muzzle? It would require some force to get them past the tight spot, especially with wheel weights, which might not be bad since to goal is to get rid of the tight spot!

Thanks,
John

[omgb]

I don't see why not. The bullets MUST be loaded from the muzzle if this is to work. Bullets should be cast from wheel weights not pure lead and not linotype. They need to be about 11-12 hardness and ww is just about right. Without lube, on a sheet of glass or flat steel put a gob of the compound on the plate. Start with the coarse grit. You will need another sheet of glass or steel and after placing the bullet in the grit and between the plates, roll the bullet back and forth until it is embedded with the compound. Bullets that are properly loaded will look dull gray. Make about 30 of these. Load them into a CLEAN and DRY barrel. Fire and then clean and dry and load again. 40 grains of 4F or 3F will cause the bullet to upset fully very quickly. More than this may cause the bullet to cut or strip and it adds fouling to the bore unneccessarily. After the first ten rounds, you will notice that the bullets load MUCH more easily. Keep going util you have loaded and fired at lease 20 rounds. It may take 30 or more but see if the tight spot is all gone by 20. If so, stop there.

[KCSO]

Thats not really a tight spot. That is where scale built up because they didn't coat the bore before welding. If I were going to lap the bore I would pull the barrel and lap with a cast lead lap from the breech. You don't remove a lot of material when you lap, but what you want is to taper the bore so the muzzle is tighere than the breech. In fact the last one I lapped afet I got the barrel smoothed a little I made a stop on the ram rod and lapped only to within 3" of the muzzle. This is a little more work, but does give superior results.

[omgb]

Hmm, scale due to welding is possible. However, is that tight spot under where a dovetail was cut for the sights or over one of the barrel lugs? If so, it is a genuine tight spot. A taper in the bore is to be prefered but may not work out so well in a muzzle loader. If you are shooting round balls you may not get as tight a fit in the bore without some loading difficulties. With minie types or T/C maxies, a tapered bore is going to make loading a great deal tougher after the first shot or two.

If you google "firelapping muzzle loader" a number of sights will come up. You should check these out before deciding.

[Underclocked]

I wouldn't mess with that barrel. Rather I would contact CVA, describe the problem and ASK for a replacement barrel.

[omgb]

Try this site for an honest discussion of firelapping a ML. I did and used this info to greatly improve mine. http://www.beartoothbullets.com/tech_notes/archive_tech_notes.htm/48


R J Talley

[garandsrus]

Everyone,

Thank you everyone for your comments... I will more than likely use the Beartooth method to fire lap the barrel.

John

John

[garandsrus]

Hi,

I am getting ready to lap the barrel and re-read the Beartooth method. Here is a portion of the instructions:

Preparation of the lapping bullets is made by imbedding a 320 grit silicone carbide lapping compound mixed in a high lubricity carrying agent (Beartooth Bullets Lapping Compound), into the surface of the lapping bullet

What else can I use as a high lubricity carrying agent? I was thinking of just using black powder lube (beeswax and crisco) or bore butter. Any sugestions?

Thanks,
John

[omgb]

Doesn't the compound already come in a paste? if not, I would think that mixing it with a good medium grease would do. A tube of RIG/Tetra/Outers gun grease mixed with the compound would be far better than BP lube.

[garandsrus]

OMGB,

I guess I should have opened the containers! It does come in a paste form. I thought it was just the grit in powder form.

Thanks!
John

[omgb]

No problem. Be sure to really roll those lap bullets through that paste util they are a dull gray in color. It will take at least three or four minutes of rolling to problerly load them.

[Newtire]

This may not be exactly the same as what you are talking about but I did this once to my old muzzleloader I inherited from my Dad. Belonged to my Great Grandpa. This gun had a bore so rough that it would tear the patches. It was a 1-48" twist .38 cal. Couldn't believe this gun shot worse than my TC "Hawken". Got talking to a guy who instructed me how to make a cutter to "fresh-out" the rifling. I had heard of this before & decided to try it. I made a cutting tooth from a piece of file that resembled a chainsaw tooth about 1/2" long X 3/16" tall X as wide as the rifling groove. I imbedded this tooth into a 3/8" (.375") dowel rod and followed this with a "cleaner/raker" tooth. I put it into the rod deep enough so that it would make a light cut and ended up making it cut on the way out. It took a couple of weeks of careful cutting in my spare time but eventually, the rust that was coming out began to be nice smooth steel. I shimmed the cutter just a bit at a time with paper to take a slight cut. At first, was rough but once it got going, came out like a million bucks. That rifle now puts em into less then 2" all day long with anywhere from 40-60 gr. (70 burns the patch) of Pyrodex-P. I know that some of the purists would turn in their armchairs about someone messing with an original but I am thinking that Eliphalet Remington would be happy to see one of his barrels shooting again. the rifling is now nice & defined. Sure looks alot better than it did before too. Letting the thing sitting with all that growing rust isn't a good thing in my book. Anyway, just thought I would share that. It's the most successful thing I ever did to a barrel is all. Afterwards, I lapped it with a patch & different grades of old Clover lapping compund and then JB.

[RugerFan]

The LBT lap instructions for muzzleloaders say to cast a pure lead "lapping skag" (I used a cleaning rod eyelet) using the last 1 1/2" of the bore at the muzzle. You then apply the lapping compound to the skag and hand lap the bore. This did seem to improve my CVA inline. I'll scan and e-mail the complete instructions if anyone is interested.

[fiberoptik]

Sure, I've got a few CVA's kickin around here. Don't shoot as well as I feel they should either.
fiberoptik@chartermi.net

[brayhaven]

Thats not really a tight spot. That is where scale built up because they didn't coat the bore before welding. If I were going to lap the bore I would pull the barrel and lap with a cast lead lap from the breech. You don't remove a lot of material when you lap, but what you want is to taper the bore so the muzzle is tighere than the breech. In fact the last one I lapped afet I got the barrel smoothed a little I made a stop on the ram rod and lapped only to within 3" of the muzzle. This is a little more work, but does give superior results.

This is good advice. As a gunsmith, I've never found the shooting laps to be very good compared to a lead lap that you can use where, & how much you need it in the bore. I use a cheap military cleaning brush @ 30 cal. Put a patch round the tip that fills the bore, push it into the muzzle keeping the threads above it end and center it. Pour in lead to just under the muzzle and you have your lap. Mark the top flat with a center punch so you can put it back the same way if it comes out. punch it out and slather it with whatever abrasive you need. For a rough bore, start with valve grinding compound and work up to 600 grit silicon carbide powder & oil. Use long strokes and you can feel the bore smoothing out. Be sure to remove all abrasive with hot soapy water prior to shooting.
Some will tell you to use patches of scotchbrite. Never do this!
I lap a lot of ML barrels & all cut rifled barrels. It's easy & usually improves accuracy, loading, cleaning & break in time.
Greg

[garandsrus]

Greg,

Thanks for the idea of using an old cleaning brush to hold the lap! Great idea.

Do you need a different lap for each grit of compound?

John

[brayhaven]

Greg,

Thanks for the idea of using an old cleaning brush to hold the lap! Great idea.

Do you need a different lap for each grit of compound?

John

No, I just wash it good between grits with soap & water or brake parts cleaner etc.
Greg

[shooter575]

I do about the same thing.I use a long 8-32 screw [or what ever fits your rod]and washer to hold the lap.Washer does not need to be tight fitting as patches keeps lead from running past.
I allways use a new lap for each grit.Some of the corse grit will inbed into the lap and still be there in the next finer charge.

[garandsrus]

Well, I finally shot some of the lapped slugs... They were REALLY hard to seat. I had to use a hammer on the ram rod to seat the bullets. I'm not talking light taps either! It was just about all I could do to seat the projectile at the bottom of the barrel.

Is this what I should expect or am I doing something wrong?

Here's what I did:
1) Sized the cast ACWW boolits to .500 (previously had problems with slightly oversized bullets loading difficultly)
2) Rolled them in lapping compound (220, 320, 600 grit)
3) Loaded with a 50 gr BP charge

Not that there is no LUBE and in fact the driving bands are coated in abrasive.

Thanks,
John

[RugerFan]

It may be the type of bullet you're using. Beartooth says to use a hollow-based mini with a thick skirt. BHN should be 11-12. Here is a link to the how-to article:

http://www.beartoothbullets.com/tech_notes/archive_tech_notes.htm/48

[garandsrus]

Rugerfan,

Thanks, I had read that link before and re-read it just before I embedded the grit in my boolits. I am using a Lee inproved Minie bullet mould 500-360-M (50CAL). The allow is ACWW. Here's a link to the boollet (http://www.midsouthshooterssupply.com/item.asp?sku=0000690472).

What type of fit of the bullet to the barrel should I be looking for when lapping the barrel? Should it be a "very tight" fit (which is what I have) or loose enough to easily seat?

With lube instead of lapping compound, and pure lead instead of WW, the boolits seat very easily, almost too easily to where I want to hone out my push though sizer by 1 to 1.5 thousanths.

Thanks,
John

[RugerFan]

I'm guessing you would want a snug fit, but probably shouldn't have to pound the bullet down the bore. Maybe try some different bullets or size down what you have. I would e-mail Beartooth and explain your issues.

You also might want to consider hand lapping your bore. I did just that with LBT lapping compound and it worked on my CVA ML. PM me your e-mail and I'll send the LBT lapping instructions if you like.

[RugerFan]

John,
The PM function is goofed up right now. I see I have a PM from you, but now I can't retrieve it. I assume Willy will have that fixed pretty soon.

-Todd