David Tubb's Final Finish Bullets. (Fire lapping a barrel)

[ravot22]

I've been reading about fire lapping a barrel to improve accuracy on a factory barrel and noticed most people had some improvement with Final Finish Bullets.

I assume these final finish bullets "smooth" the barrel.

My question is wouldn't firing 200+ rounds of regular ammo smooth out a factory barrel as well?

 

[gohring3006]

I personally wouldn't fire lap a barrel until I exhausted every option to make a gun accurate. (Bedding,free floating,trigger, recrown, etc. I feel there is no control in the fire lapping process. Is the throat getting lapped more than the barrel, or is it the opposite.. Hand lapping is more effective in my opinion. I would fire lap as a last ditch effort to get a barrel to shoot, if not its time to rebarrel.

 

[tim_w]

Actually I have a good bit of experience with it. Where is helps is when you start to have moderate throat erosion and the loss of accuracy or a rough factory barrel when you have noticeable increase in fouling from the erosion or rough throat/bore respectively. Its certainly not the only way to skin this cat but it does work.

Unless you have actually held and felt these bullets personally I think many (not all of course) will get the wrong impression and picture some rough sandpaper coated bullets going down their pretty bore. They are very low grit in fact they feel and look more like the roughness you might have from oxidation from putting a jacketed or solid copper bullet in a mild copper solvent.

I only ever used the the last levels of grit bullets I never not once used the first two heavy grit levels and they are almost never needed and in fact IMO its much better to only buy the specific ones you need instead of the actually kit. If you call them they should let you purchase exactly the grit steps you want. At least they did in the past.

These are not something you need with a new fresh custom hand lapped barrel for sure. For some factory barrels they really do make a difference

Looking more than I care to recall thru that bore scope; testing various methods it did make a noticeable difference in the throat area when it started to have the mild cracking and lowered copper fouling or machining marks etc from cutting the chamber on some factory barrels. Its more like what you could get from some work with JB bore paste but faster and in only the direction of fire. But its real use IMO is cleaning up a rough factory stick.

Do I think its something everyone needs to use? NO But I do see places where it does and has extended the accuracy life of barrels and more so has helped improve things on rough factory barrels where it can make quite a difference in fouling and "depending on the issue", accuracy. Its really something I think is up to the user and what their situation is and what components they are working with. From seeing way way to many before and afters if you only use the last few grits, on basic factory tube I can not see it doing any harm and very well could help. But if you have a gun that is shooting close to .5 moa I would not use it for the goal of thinking you might get to .25 moa. More than anything it helps with fouling.

I had actually had customers pay me to run theses down the bore for them as a service on a new build. ( these were for ARs to be clear) One place they work well is with chrome lined barrels. The type used in mainly AR builds (before I went to nitriding (PQP) AKA meloniting all of them back in 06'-07'. With both types of barrels I always final polished them with flitz or some other very mild polish. In fact its usually mandatory with meloniting as most if not all the treatment manfs polishing media is too large to be effective in the small bore diameters as opposed to the outer surfaces. Its like a reverse Tubbs final finished with the bore surface like one of the higher grit bullets. As would be expected, if you choose to fire a fresh nitrided barrel without polishing the bore you WILL get heavy copper fouling and high pressure and many times blow primers and or cases (a fairly well known piston AR manf found out the hard way or should as say the customers when they switched to nitrided without doing due diligence of the process)

I am a big advocate for meloniting/nitriding barrels.



To the op:

The first thing I would consider is did you break in the barrel i.e. shoot and clean shoot and clean etc? At some point did copper fouling make a noticeable drop off?

Regardless do you still see a fair amount of copper fouling?

Ideally as a very first step find someone with a bore scope that you could use or they could and allow you to look on and see it. Careful inspection of the throat and then the entire bore.

First step I would do as long as you do not mind the work:

Polish the chamber and throat with flitz or maybe even JB bore paste. Find a mop that fits but does not go past the the throat. Load it with polish and low speed with a drill (again we are talking factory barrel) DO NOT LET IT HEAT UP or dry out. Work it very careful. Its just time and no reason to ruin a barrel just to save a small amount of it. Clean it well.

Then start with flitz and start stroking that barrel bore. Give it say 100 passes. Clean it up really good. Take it out and shoot a few rounds to foul the bore. Push a patch down it and then shoot it for groups. Also see how it compares in terms of fouling after you have a enough down it to make a judgement.

What I like to do is 1: push a tight dry patch down the barrel before I start the polishing process and take note of the feel of it. Then 2: do it again after you have finished lapping/polishing the bore. You should notice it going much smoother if it was a mildly rough bore.

If you still feel more work is needed use only the last two grits of final finish.

I would also take careful magnified inspection of the barrels crowns edge. It should be a sharp and consistent clean edge with no chips out of the lands where they meet. If not then you need to clean that up or have it cleaned up.