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Fire Lapping a Barrel

 
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  #8  
Old 04-24-2013, 11:24 PM
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Join Date: Jul 2004
Location: Texas
Posts: 5,533
Re: Fire Lapping a Barrel

I have done more than 50 RUMs and they always show great improvement in SDs, ES and accuracy and it takes 2 more grs of powder to get back to the previous max pressure but with increased velocity. Don't let anyone tell you the don't work or that they harm your bbl because if you do it right you will be happy!! ---- RHB[/QUOTE]

I agree to disagree with this and I will tel you why.

I have only done 1 and that was enough for me. I have hand lapped lots of barrels when they had poor
accuracy. One barrel was so bad I figured, what did I have to lose because the next step was
to replace it (It would not shoot less than 5" groups at 100 yards ). I throughly inspected it with the bore
scope so I could compare the results and even cast a broach to check the bore size after the
fire lapping.

Having this barrel to sacrifice if I couldn't,t fix it, I followed the instructions to the letter and waited
5 min between shots to give the barrel time to cool down.

After completing the fire lapping and still at the range and good cleaning, I fired the best loads I had
for it before it was fire lapped and it did improve to around 3'' groups and it did drop in velocity.
It was better in every way but it was still not good enough to save the barrel from being used as
a tomato stake.

After getting it back in my shop and inspecting it again with the bore scope most of the machine marks
were gone from the throat end but very little had been changed on the muzzle end.

Inserting the broach I cast earlier I found slight resistance at the muzzle but none at the chamber
end. Not wanting to give up on the fire lapping I cast a broach at 1" from the chamber end and
that's when I decided never to use that system on any rifle that was to be used for more than 100
to 200 yards because of bore taper. the lap would not go but 4" or 5" toward the muzzle .The only
thing that helps is the fact that as the bullet moves down the barrel it gets tighter.

On this site everyone worries about barrel life and this method has to take several hundred rounds
off the barrel life (Lower velocity and 2 or 3 more grains of powder to regain the velocity, only
enforces the end results) .A tight, smooth barrel normally increases velocity.

I would never tell anyone that they shouldn't do something, I just tell what I have seen and prov en
to my self and if they chose to do something else good luck to them.

My test was a worst case scenario and with a better barrel I am sure the results would be better from
an accuracy standpoint but to purposely remove several hundred rounds of barrel life from a barrel
just doesn't makes sense especially on one that shoots well, but fouls after 2 or 3 shots.

This is just My experience with this system and the explanation for the reason that I don't recommend it.

Nothing personal.

J E CUSTOM
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  #9  
Old 04-25-2013, 12:21 PM
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Join Date: Jan 2005
Posts: 338
Re: Fire Lapping a Barrel

JE, sounds like you used the whole kit!! As I said that's a bad idea. 5 minutes apart on a ten shot string is not going to keep the bbl cool enough. The last three or four shots were doing damage, especially if you were using the 1s and 2s. If your load was at 2900 fps or higher you were doing damage. I try to keep the load between 2500 and 2800 fps for the best results. The velocity decrease is from a very slick bbl, the same as you would get from using Moly or Tungsten disulfide.I haven't noticed any of the other complaints you have mentioned. We have put together hundreds of factory rifles using Tubbs final Finish, Great pillar bedding, great brass work and great load development ( Good Grouper ) to make great shooting,long range hunting rifles that will shoot sub MOA at a 1000yds or more!!! Tubbs Final Finish works if done correctly!!!! ---- RHB
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  #10  
Old 04-25-2013, 01:50 PM
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Join Date: Dec 2012
Posts: 7
Re: Fire Lapping a Barrel

A couple months ago, I used a Tubb FF kit (#1 thru #5) on a Factory Remington CDL 30-06 with the fly rod sporter barrel. Before using the FF kit, the rifle would shoot no better than a 2 1/4", 5 shot group at 100yds. The bore would also visibly copper foul after just one or two rounds. After 132 rounds of factory ammo through the barrel and one poorly placed shot on a whitetail last fall, I was resigned to a re-barrel job or to sell the gun. That's when someone suggested the Tubb kit.

I used the .308 Tubb kit and followed the directions to the letter. It took 2 weeks to get it done but the difference was obvious - just under 1 MOA at 100 with the same box of factory cartridges. Plus, the copper fouling cleans up with just a couple wet patches of BT Eliminator.

Since I use this rifle at considerably shorter ranges than most on this forum do their rifles, I'll consider this one done, as long as it will hold the < 1 MOA. And with the cost and scarcity of ammo and components to reload, I won't be shooting it much except during hunting season to fill the freezer.

The take-away from this experience for me has been as a last resort, why not? On a custom rifle with a aftermarket barrel, built to tighter tolerences, unless it is copper fouling excessively, the problem is more likely something else.
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  #11  
Old 04-25-2013, 09:43 PM
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Join Date: Apr 2013
Location: North Texas
Posts: 4
Re: Fire Lapping a Barrel

I appreciate everyone's input. My uneducated guess was that most of the lapping would occur in the throat and first third of the barrel because most of the compound on the bullet's jacket would abrade off the bullet before it exited the muzzle.

I'm ok with the accuracy of the rifle as it is but not thrilled with it. Now throw in the fact that I can't get more than 3 or 4 shots before it has to be cleaned and I've decided to use this rifle as a test bed. If fire lapping works and I can get the accuracy and performance out of it I want then I will continue to shoot it as it is. If it does't show the improvements I want then I have barrels in the safe that I can use to turn this one into either a 7 LRM or another 300 RUM.

I'm going to document the current load I'm shooting, muzzle velocity, accuracy and free bore both before and after then let the numbers decide what happens next.

Thanks again for sharing your experiences.
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  #12  
Old 04-25-2013, 10:14 PM
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Join Date: Aug 2009
Posts: 56
Re: Fire Lapping a Barrel

I can hardly wait to see the results, i'm waiting on a 6mm improved....should be done in a couple of wks, the barrel is a kreiger 8 twist, and i was going to run the tms kit with it...As per david tubbs instuction.....
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  #13  
Old 04-26-2013, 07:47 AM
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Join Date: Dec 2005
Posts: 2,114
Re: Fire Lapping a Barrel

I don't think a Kreiger barrel needs to be "conditioned" in any way. Too many folks have shot them as is and won matches setting records doing so and so on and so on.......

Nor does any other barrel need to be "conditioned" if it's made right. If it ain't made right, why buy it in the first place?

Any time the hole in a barrel's made bigger, there's less resistance to the bullet starting down it and pressure will be less. So will muzzle velocity.

Every "rough" bore barrel I've shot produced better accuracy after a few rounds laid copper in those rough spots so subsequent bullets would not be unbalanced from jacket material being scraped off. Never ever had one that had accuracy get worse after copper fouling.

The most accurate barrels I know of all have the same bore and groove diameters all the way from leade to muzzle. No taper whatsoever. Good barrel makers lap barrels to less than .0001" spread the entire length of the rifling when the blank's finished. Fire lapping a barrel makes it taper tighter from its hind end forward. Borrow a Sheffield air gauge then measure your fire lapped barrel.
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  #14  
Old 04-26-2013, 09:42 AM
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Join Date: Jul 2004
Location: Texas
Posts: 5,533
Re: Fire Lapping a Barrel

Quote:
Originally Posted by Bart B View Post
I don't think a Kreiger barrel needs to be "conditioned" in any way. Too many folks have shot them as is and won matches setting records doing so and so on and so on.......

Nor does any other barrel need to be "conditioned" if it's made right. If it ain't made right, why buy it in the first place?

Any time the hole in a barrel's made bigger, there's less resistance to the bullet starting down it and pressure will be less. So will muzzle velocity.

Every "rough" bore barrel I've shot produced better accuracy after a few rounds laid copper in those rough spots so subsequent bullets would not be unbalanced from jacket material being scraped off. Never ever had one that had accuracy get worse after copper fouling.

The most accurate barrels I know of all have the same bore and groove diameters all the way from lead to muzzle. No taper whatsoever. Good barrel makers lap barrels to less than .0001" spread the entire length of the rifling when the blanks finished. Fire lapping a barrel makes it taper tighter from its hind end forward. Borrow a Sheffield air gage then measure your fire lapped barrel.

Thank you Bart !!!

I was beginning to think I was the only one that did not abuse barrels. I have re barreled many barrels that had been abused one way or the other and hate to see a quality barrel like the Krieger Fire Lapped.

I know that seasoning or breaking in a barrel takes time but it is well worth it. (There is no free
ride) taking short cuts leads to bad things. That is the big difference between a good smith and
a bad one.

To save money a person that though he needed to lap a barrel used the rubber abrasive tips that
are used on a Dremel tool to "Fire Lapp" his barrel. When I bore scoped it, it looked like it had been through two wars. It ticked me of to see a fine barrel treated this way so I declined to re barrel It
not knowing what he would do next.

The logic is very simple, "ONCE YOU REMOVE BARREL MATERIAL YOU CANT PUT IT BACK" And if you taper the bore it is worthless. Barrel makers go to great lengths to Gage bore diameter and most
reject them if the barrel has more than .00005 difference end to end.

Gun smiths and barrel makers rejoice , this means more barrel jobs and faster barrel burn outs.

PS : I did follow the instructions to the letter and 5 min. between shots (1 hour and 20 min is plenty
of time to allow the barrel to cool for 10 shots. And everyone that wants to try it should, that way,
they can learn the hard way. I promise not to try and talk anyone out of doing this anymore In fact I should encourage it because it is job security for lots of gun smiths.

As my signature states "Press ON"

J E CUSTOM
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