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Teach me to lap barrels (PLEASE)!

 
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  #8  
Old 12-30-2012, 07:38 PM
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Re: Teach me to lap barrels (PLEASE)!

IMO you are going to make a lot of barrel mftrs real happy!

There is a reason the mftrs cut off the last 3/4 to 1" of the barrel when done lapping. The guys that do it for a living all day cannot keep from opening up the end of the barrel and you really think you can?

You have no idea what you are doing. No idea of what the initial and final dimensions will be and no way to measure anything. Plus you asking for advice from people that do not do it for a living. Call krieger or Tim North at Broughtkn and see what they tell you.

Think about that for a moment. Recipe for disaster on a barrel.

Yep they will be real happy with you screwing up the barrels!
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  #9  
Old 12-30-2012, 07:55 PM
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Re: Teach me to lap barrels (PLEASE)!

BH I agree, OP if your working with something you don't mind destroying go ahead.
A bore scope sure would help you determine what you are accomplishing as well.
If the barrel is already chambered you risk washing out the throat, the barrel crown can always be cut back and re crowned.

I practiced on a couple of remy take offs, then tried it on a adams and bennit barrel that still needed to be cut down and chambered.
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  #10  
Old 12-30-2012, 08:42 PM
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Re: Teach me to lap barrels (PLEASE)!

Why not try that "Tubbs Final Finish" system (may not be the proper product name...) , where you fire a few bullets that are coated with a mild abrasive, starting with coarse and ending with fine... I havent used it, but Ive handloaded the abrasive bullets for a few of my customers, and a couple have gotten good results.. especially with old mil-surp rifles. Personally, I would invest in a borescope before attempting hand lapping. Good luck!
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  #11  
Old 12-30-2012, 08:58 PM
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Re: Teach me to lap barrels (PLEASE)!

A Hawkeye will set you back about 800 bucks btw. I have one and it's great to use for checking your cleaning regimen. I use mine in the shop for looking in machined cavities, checking internal threads and looking inside assemblies that can't be taken apart.

Great tool. I got one for the guns and I've used it for everything else but guns.

Me. I wouldn't even consider lapping any barrel until I had a peek inside to ascertain, if, its actually a machine roughness or something else. The Hawkeye is great for checking throat erosion too.

There are some others on the market but the Hawkeye has the smallest diameter barrel. I believe it will fit a 22 caliber (223 bore).

Keep in mind, it's a precision instrument so it needs to be handled like a precision instrument but then, if you pay 800 bucks for one, I imagine you'll treat it carefully.
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  #12  
Old 12-30-2012, 10:15 PM
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Re: Teach me to lap barrels (PLEASE)!

Back when I was an aerospace engineer I had access to borescopes. When I worked at Amsco Scientific we worked with them regularly. Sure I would like to have one now, but I can't hardly justify the cost of a borescope to work on ONE used rifle.

The rifle has a stainless barrel and has been fired VERY little. When I got it the first 2 shots fired OK, then I had over pressure signs with factory ammunition. After stripping all copper from the barrel I was able to get 3 shots off without any over-pressure signs, but #4 was definitely over-pressure. Stripping the copper from the barrel again got me 3 shots before the pressure spiked. With a tight patch I could definitely feel the roughness in the center of the barrel, starting about 4" from the chamber and ending about 6" from the muzzle.

I was investigating fire-lapping the barrel but it was explained to me that this was not as good as hand-laping. Looking through reviews of fire-lapping bullets I saw good results with barrels that didn't need a lot of work but less improvement in barrels that needed a lot of work. This barrel obviously needs a lot of work so I was looking at hand-lapping.

I presumed I would not lap the last inch or two of the barrel so I could avoid possible damage to the muzzle. I also have no intention of going crazy lapping the barrel I want to do just enough that bullets, or possibly fire-lapping, could do the rest.

I also intend to replace this barrel with a longer one at some point in the future although I didn't plan on doing that immediately. I accept I bought a gun that was "less" than I expected and, under the circumstances, I paid too much. I got burnt the question now is how to mitigate the damage. Do I fire-lap it? hand-lap it? or simply order a new barrel? (There is one other option, ship it to the factory & tell them to figure out why this happened.)

I also looked into having the bore electro-polished but saw where rough barrels are generally lapped prior to electro-polishing. I presume this barrel would need to be lapped prior to electro-polishing.

My post here was to understand hand-lapping barrels so I could decide if this was the way to go. I still lean towards hand-lapping, but people have given me pause to think about whether this is the right choice. The more people have said, the less I am sure this is the right way to go.
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  #13  
Old 12-30-2012, 10:17 PM
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Re: Teach me to lap barrels (PLEASE)!

Quote:
Originally Posted by SidecarFlip View Post
A Hawkeye will set you back about 800 bucks btw. I have one and it's great to use for checking your cleaning regimen. I use mine in the shop for looking in machined cavities, checking internal threads and looking inside assemblies that can't be taken apart.

Great tool. I got one for the guns and I've used it for everything else but guns.

Me. I wouldn't even consider lapping any barrel until I had a peek inside to ascertain, if, its actually a machine roughness or something else. The Hawkeye is great for checking throat erosion too.

There are some others on the market but the Hawkeye has the smallest diameter barrel. I believe it will fit a 22 caliber (223 bore).

Keep in mind, it's a precision instrument so it needs to be handled like a precision instrument but then, if you pay 800 bucks for one, I imagine you'll treat it carefully.
+1, here! Ya' gotta' be able to see the problem/see what you're doin'. Other wise is just a darned poor guess. At least with a bore scope it'd be an 'educated' guess.
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  #14  
Old 12-30-2012, 10:39 PM
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Re: Teach me to lap barrels (PLEASE)!

Id fire lap it. I wouldnt run those thu a hart or lilja but a factory heck yea. Ive used it on quite a few 30 cals and had it work. Use a light load and start with the 3rd stage and run them. If that doesnt fix it hit it with a full course. What do you have to lose? Especially if you can FEEL the issue it needs some serious work.
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