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Old November 13, 2020, 08:26 PM   #1
Shadow9mm
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tubbs final finish bullets

So I bought a TC Compass in 30-06 the the gun was always filthy after shooting and hard to clean. It also had a somewhat short throat. I made the mistake of looking down the barrel with a bore scope and it had a lot of tool marks. I used the tubbs final finish bullet sytem, 50 bullets, 5 different grits, 1 rounds per grit with a cleaning in between.

In short, it did work, but not as well as I had hoped and not consistently throughout the barrel.

I only took 1 before, but the before was fairly consistent over the length of the barrel, a little better in some places than others, much better on the lands.

Before



After 1 and 2


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Old November 13, 2020, 08:31 PM   #2
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Looks much better to me, especially at the edge of the grooves. The important thing is, does it shoot any better? I just bought some of their finishing packs for my worse-looking barrels.You say one round per grit--I thought the instructions say use all ten bullets per grit (unless your keyboard dropped the zero, which is what I figure since you say "rounds" )?
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Old November 14, 2020, 06:41 AM   #3
std7mag
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It's a TC Compass.
The Final Finish isn't going to turn it into a Criterion, or Bertlien barrel.
Looks much better to me.
Shoot it & see what the results are.
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Old November 14, 2020, 11:24 AM   #4
HiBC
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There are high,jagged peaks . There are deep valleys . You can knock the tops off the peaks and come up with plateaus.
That may be the best you can do. Plateaus are pretty good.
Its a mistake to think you need to remove the low spots.

The secret of a good polish is a good tool finish. You aren't going to transform a moderate cost production barrel into a Harry Pope work of art...unless maybe you are Harry Pope.

I have had a cheapo barrel with a smeared cheese tool finish that shot about

2.5 MOA +,getting worse as the copper caked up.....I figured I had nothing to lose,I rolled some cast 30-30 bullets in diamond mold polishing paste and shot about 20. Of course,I had my rituals around the process,salamander sweat,drumming,burning sage,etc.
It transformed into a near 1 MOA barrel that was not a bad fouler.

Not to argue with David Tubbs,I use all one grit,a Gesswein (IIRC) green # 9 diamond compound. Its really fine,but it cuts good.I forget the micron.

I'll guess maybe 1200 grit? or 900?
What I have learned about lapping fits is the larger grit cuts a greater clearance. Using the same diameter bullet,a 240 grit will lap a bigger size hole than an 800 grit. The bullet with the fine grit,if the bullet is the same diameter,will just rattle through the hole lapped with coarse grit.

Remember that if you lap a 1911 slide to a frame. If you start with 320 grit you are using approx .003 screen rocks. Some of the rock will embed in the softer material,and become a tooth that will be driven by the soft piece to cut the hard piece. Your 320 grit may cut .0025 to .003+ clearance all around,per side.

Now,you come back with a fine 900 grit,which will screen about .001. Some of the .001 embeds. Maybe it will cut .0006 to .001 per side clearance,all around.

The 320 already left .003 clearance. Your 900 has nothing to cut.

I lap a fit with my finish grit only. And with that grit size I can control my clearance size

I was not making barrels. General toolmaking
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Old November 14, 2020, 01:56 PM   #5
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Quote:
Originally Posted by HiBC
I figured I had nothing to lose,I rolled some cast 30-30 bullets in diamond mold polishing paste and shot about 20. Of course,I had my rituals around the process,salamander sweat,drumming,burning sage,etc.
It transformed into a near 1 MOA barrel that was not a bad fouler.
Would you share the source of the diamond paste?
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Old November 14, 2020, 04:50 PM   #6
HiBC
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Gesswein is top of the line stuff. Its not cheap.
This link will take you right to a tube of green # 9 diamond.
This is a place you can find about anything for mold and die finishing

https://www.gesswein.com/p-11732-ges...high-temp.aspx

Its been a few years,this "high temp" idea is new, Kerosene or alchohol worked as lube/fluid. A wet patch ever few shots might be good.Use the diamond sparingly. I might spread thin on a a hardened/ground parallel then roll the bullets in a sandwich between two parallels.Or,a couple of pieces of glass.

Last edited by HiBC; November 14, 2020 at 04:59 PM.
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Old November 16, 2020, 11:51 AM   #7
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If you're going to do this 'rolling your own' fire-lapping ammo, use the longest bullet you can, and used a reduced, lower powder load.
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Old November 16, 2020, 12:07 PM   #8
HiBC
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I was doing a 30-06. I used approx 170 gr 30-30 cast bullets loaded to 30-30 levels. It worked for me.

Another approach I might use is order the Tubbs bullets,just order a bunch of the fine grit. Skip the grit progression. No coarse grit.

I concede,I can't shoot with David Tubbs. But I did spend decades building and finishing steel plastic injection molds.

When my employer sent me to understudy a Master Mold and Die finisher,he was working on some coining dies for a Mint.

I have polished tungsten carbide mirrors used in satellites for optic control circuits. I know some about lapping and polishing while holding form and dimension.

I'm not a barrel maker. But I have successfully improved a button galled cheap barrel.
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Old November 21, 2020, 09:45 PM   #9
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Tubbs bullets

HiBC: What you're saying about grit sizes makes sense to me. Never thought about it that way! I was a toolmaker/template maker, not a die maker, so have little experience polishing for fit, but it makes perfect sense that a large grit is going to cut more clearance than a smaller size. I have a barrel that tends to copper foul badly. When I get a chance I'll try your method to see if it helps.
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Old November 25, 2020, 09:42 AM   #10
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It's complicated. The standard grades of abrasive have a pretty wide particle size distribution. As I understand it (HiBC, please correct this if you know otherwise) this has two possible effects: When your lap is fairly hard and the work is equally hard or softer, the big particles make big scratches. When your lap is soft, like a cast lead bullet against steel, the big particles tend more to embed in the lap rather than scratch up to full diameter, but another problem still exists, and that is the fine particles at the small end of the mix packing around the bigger particles and slowing their cutting action down.

I read some years ago about amateur telescope makers in the UK figuring out laboratory-grade abrasives that have a narrower particle size distribution cut twice as fast as the standard grade. In that instance, the work is hard (a glass mirror blank) and the lap soft (usually cast pitch). The NECO firelapping kit also uses laboratory-grade abrasives. I am unaware of any others that do. I can say the NECO kit makes fairly quick work of things.
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Old November 25, 2020, 06:03 PM   #11
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The Gesswein supplies are very high quality. I can assure you,if you work an EDM finish mold cavity to a flat,distortion free mirror finish,the tracks left by a stray oversize rock will tighten up your jaws!!
In my experience,lapping is about using the softer material as a matrix the grit particles embed in. The soft material drives the grit and cuts the hard material.

At my trade I typically used brass or cast iron laps. My two main power tools were a profiler and what looked like an overgrown Foredom on steroids.
Its 1/2 hp 10,000 rpm with a 1/4 in collet,and reducer collets.
The profiler is pistol shaped. A 0 to 14,000 rpm drive cable enters where a magazine would. Up top,where the breech would be,is a zero to 6mm variable eccentric,so I can apply a zero to 6mm eccentric stroke to a barrel,pointing like a gun barrel,out the front. I can clamp stones in it,or drive a lap with it.
The lap will float on the workpiece like a dustmop. My right foot runs speed control. So I have up to 14,000 reciprocal strokes a minute.

The rotary tool drives a sisal end brush or felt wheels.

Gesswein makes pretty good polishing stones,but they are sintered. Pressed and baked. While ther grit may be true,they can drop a clump,and that digger can spoil your work.

We used puddle stones. High grade grit is sifted into water. It settles out and become much like a japanese water stone. I'd saw my stones out of a block.

I think you are right,the bigger rocks get the cutting done,smaller rocks are clutter.They dont engage much. And,like a hard Arkansas stone,steel can clog things up. We used mostly a version of kerosene to maintain a proper slurry.
Too wet wastes diamond. Too dry...sort of galls.

I'll see if can find anythng n youtube
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Old November 30, 2020, 05:18 PM   #12
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My Savage 10T in 6mm CM had a rough bore. When cleaning it I could feel the roughness. I had properly broke in with the shot, clean, shot ,clean...method. I noticed it had a lot of copper fouling. not at all smooth as other rifles I own. The rifle shot good but nothing to wright home about. I decided to take a chance with The 50 pack of lapping bullets from Tubb. The rifle is very capable now of one hole groups. I didn't get much shooting in with it before I Tubbed it. Although I can tell you that now it is capable of shooting house flies off White paper at 100 Yds. with consistency. And I'm not blowing smoke. Just telling it like it is.
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