Author Topic: Muzzleloader Lapping ?  (Read 1425 times)

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Offline Ricci Price

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Muzzleloader Lapping ?
« on: October 31, 2005, 07:55:49 PM »
I have a 45cal smokeless muzzleloader barrel installed on a Harrington and Richardson, the barrel is a Adams&Bennett 4140 chromoly, 458cal (45-70 replacement barrel) 1 in 22" twist. The barrel has radial drill marks on top of the lands although they are not as visible the drill marks are in the grooves too, indicating this is a button rifled barrel. I get consistent 1" 3 shot groups at 100yards with this barrel, but I have to really clean it between shots, using a bore brush, then a patch soaked with hoppes then dry patches. I am using a 40cal 200 grain saboted bullets, IMR4198 powder, and 209 shotgun primers and getting around 2600fps. I am guessing that lapping would help with cleaning. How could I use the lapping compound for this barrel? Could I seat the bullet in the barrel in the breech end, pour in powder and reinstall breech breech plug and shoot? or muzzle load?

Offline Veral

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Muzzleloader Lapping ?
« Reply #1 on: November 09, 2005, 05:00:37 PM »
The only way I know is the traditional method of casting a 'lap skag'.  Giving the instructions here is too detailed.

  If you want to lap, get the LBT lap kit and ask for muzzleloader lapping instructions when you order it.  Be forwarned it is HARD work, takes a few hours, and will leave your arms and back aching.  But the time can be spread out over several days and the results are very rewarding.

However.  I believe your accuracy indicates that the sabots are hanging to the rifling very well.  i.e. The rifling isn't grinding the sabots down and hurting performance.  The fouling you are getting is probably entirely plastic, and you are getting it because of speeds way beyond what the sabots are designed to handle.  Black powder loads rarely exceed, or even reach 2000 fps.  You should slow your loads down to not more than 1800 fps if you are using softnose handgun bullets, 1600 fps max if hollow point, as they will blow to powder when they hit with your high velocity loads.  The lower speed will almost certainly solve your fouling problem, and if not probably trying a different brand of sabots will.  But if you try another brand, try to learn if they are made of a different type plastic. (From the manufactures.)
Veral Smith

Offline R J Talley

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Muzzleloader Lapping ?
« Reply #2 on: January 29, 2006, 06:53:10 PM »
Veral, i just finished using your kit to lap my Lyman 50 cal percussion.  I did it this way and had excellent results. First, I cast a bunch of T/C type slugs using wheel weights. These are the Maxi-ball slugs that are slightly undersized at loading but slug up to fit the rifeling at fireing. I rolled these in your lapping compound until they were a dull gray and clearly embedded with the compound. I made twenty of these. I went to the range and using 50 grains of 4f, I shot them all. I was careful to first clean and dry the bore. Then I shot the first round. I cleaned and dried the bore again and did so after each shot. This way I knew I was lapping the lands and the grooves equally and that there was no fouling bewteen the compond and the steel. After twenty shots the bore was very much changed. First, it did not accumulate fouling at nearly the rate it did before. I could laod and fire six or seven tightly patched balls without any difficulty at all. Before lapping, I had to wipe after each shot or the load would not go down the bore easily, sometimes not at all unless hammered down.

The second part was even more remakable. Before lapping, I had two very noticable tight spots in the bore. One was under the front sight dovetail and the other was directly under the rear sight. You could feel the load hang up at each point. After lapping, the barrel felt smooth all the way down.  I finished the lapping by wraping a cloth patch loaded with JB compound and running this in and out of the bore about 150 strokes. I just replaced the patch and reloaded the JB paste as it wore out.

I used 4F because I wanted the bullet to bump up to full bore size as quickly as possible. 2F would not have done this as well. Secondly, I used a WW slug because I wanted the slug to be hard enough to hold the compound. I was afraid that pure lead would just embed the compound and not actually hold it on the surface so that it would do the required cutting.

I suppose a minne bullet would have been better but I didn't have one in 50 cal. The T/C Maxiball seemed to work out just fine.

I was concerned at first that this method might ruin the bore. Considering however that mine was pretty rough due to the previous owner's lube and storage procedure or lack there of, I really had nothing to loose.

That being said, I can't vouch absolutely that what I did will work for everyone. It did however, work very well for me. If you think I am off base please say so and I'll listen. You've never done me wrong yet.

R J Talley
R J Talley
James Madison Fellow/NRA Member/Quail Unlimited

Offline Veral

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Muzzleloader Lapping ?
« Reply #3 on: February 05, 2006, 01:45:06 PM »
I'm listening to YOU Reece!  You're the first report of lapping a muzzleloader this way, and it worked, so I won't argue!  In fact I reccomend that anyone try it, but use pure lead, as wheel weight will not bump up as well.  Pure lead will hold the compound beautifully but will loose size quicker, and lap slower than ww alloy.  Put another way, pure lead will produce a more tapered barrel, a true plus,  and a finer finish, while at the same time allowing easier seating of the bullet, which is the problem that stopped me from trying fire lapping muzzloaders.
Veral Smith