Barrel lapping

[Bass Ackward]

By definition, a Taylor throat is supposed to allow the bullet to exit the cylinder free and clear of stresses and then perform the bore alignment in the funnel created in the barrel. In order to do this, that means that the opening needs to be large enough in diameter NOT to interfere with the bullet's exit. It was made with bore diameter bullets (jacketed) in mind. Translation: here is another opportunity to lose seal that you worked to establish.

In effect, this is what in the old days was considered a worn or shot out forcing cone. A way to put 20,000 rounds of wear into a new gun so that it won't shoot loose and sound like a baby rattle when you shake it. We have reports that as a forcing cone wears, (lengthens) that you lose the ability to shoot short / light bullets because you can't maintain seal. This is not necessarily so, but it will show up for normal to low pressure cast loads that obturation doesn't occur at the lower pressure levels now present in the cone. That in itself is no big deal, unless your only lead supply is limited to WW cause you will lose load and powder flexibility chasing seal. Which is the same exact problem with a .... constriction which requires reobturation.

Bottom line is that I have access to three Taylor's and all three were used well before and after throating. I had no real accuracy improvement from peak performing loads. BUT ..... it did improve the accuracy more loads in general. (Just not enough that I would use those loads anyway.) One is now a jacketed only gun. So if you don't like changing mixes, or are limited to a WW supply, this can mean that you are now stuck to higher pressure loads.

IF your barrel is not in perfectly straight in the frame, then a Taylor is going to be cut true with the bore, not with bullet travel. That's why if I was Tayloring I would want frame alignment and thread size checked and trued, etc. If you don't correct the real problem it will have to wear (break in) anyway. If you have any alignment issues or a constriction and you fire lap, you WILL shoot in a "perfect" Taylor for "THAT" gun that doesn't create tool marks and removes metal EXACTLY where it needs removed. We know from experiences here, sometimes fire lapping or tayloring works, and sometimes results can be disappointing.

Proper diagnosis of the problem is the key. That's why I hold my opinion.

[yondering]

You can get the Wheeler abrasives (3 grits) in the (gun)smithing section on eBay, and roll your boolits (or bullets) in it and load your own abrasive rounds. The idea of using J.B. bore lappiing compound for this is qiute intrigueing too as it is a fairly mild abrasive.

I've got those, but that's a whole different thing than polishing. Those are lapping (cutting) compounds not polishing compounds. The Tubb's system polishes the bore. There's a polishing "dust" imbedded in the bullets, it doesn't feel grainy at all, it's like talcum powder.

I've already lapped the bore, as stated above. Now it probably just needs some polishing, although I've polished it with Flitz a bit already.

[Bass Ackward]

Just remember that Tubb's uses aluminum for the abrasive. The grits are very fine, yet it can and will embed in the bore.

Remember that system was created for jacketed. After you fire lap, best results will not occur until the abrasive is removed and the pores in the metal are closed. From my experience, that too is best performed with jacketed. Certainly a GC design.

Another great idea is to use LLA. You can heat LLA and mix in some very fine abrasive like carbide flour. And then that mixture can be painted only on bullet noses or only in the forcing cone with a Q-Tip so that you don't enlarge your throats. Just more ideas if that is the direction you are headed.

Don't forget to mark the bottle against mistaken use.

[machinegun]

Planning on lapping a rifle barrel in the hopes of increasing accuracy. Have been told that bon-ami may do as good a job as JB compound. Anyone have any experience with this?

[machinegun]

Planning on lapping a rifle barrel in the hopes of increasing accuracy. Have been told that bon-ami may do as good a job as JB compound. Anyone have any experience with this?

[felix]

Yes, depends on the barrel material for how fast it works. Calcium carbonate is quite soft compared to silicon dioxide. ... felix

[felix]

Yes, depends on the barrel material for how fast it works. Calcium carbonate is quite soft compared to silicon dioxide. ... felix

[yondering]

Are you "lapping" or "polishing" the bore? There's a difference. JB compound will polish nicely, but it's not going to remove barrel constrictions, which is generally the purpose of lapping.

[yondering]

Are you "lapping" or "polishing" the bore? There's a difference. JB compound will polish nicely, but it's not going to remove barrel constrictions, which is generally the purpose of lapping.

[truckjohn]

Yeah,

I wouldn't fool with Bon Ami..... Very very very very soft.
It is advertised to "Not Scratch your pots"..... which are mostly soft stainless.

We need something that will actually abrade away the steel.... like real Lapping compound.

Personally, I would leave the true Hand "Lead Lapping" operation to an experienced smith.... unless you can afford to ruin a couple barrels for the sake of learning. If so, buy a couple "Clearance" type used barrels, and lap away..... I put a nice "Fishbowl" in the middle of an old Marlin barrel this way.

On the other hand... I have performed Fire Lapping on a couple of guns now -- and it worked extremely well.

My own experience with fire lapping is.....
1. Only do the fewest rounds possible to remove the restriction/clean up rough spots.
2. Clean clean clean after with Soap and Water.
3. Clean more with soap and water.
4. Keep cleaning with soap and water.
5. Shoot about 30 rounds standard ammo, clean per regular schedule.
6. Clean clean clean clean.
7. Work up new reloads to compensate for lower velocities.

Thanks

John

[truckjohn]

Yeah,

I wouldn't fool with Bon Ami..... Very very very very soft.
It is advertised to "Not Scratch your pots"..... which are mostly soft stainless.

We need something that will actually abrade away the steel.... like real Lapping compound.

Personally, I would leave the true Hand "Lead Lapping" operation to an experienced smith.... unless you can afford to ruin a couple barrels for the sake of learning. If so, buy a couple "Clearance" type used barrels, and lap away..... I put a nice "Fishbowl" in the middle of an old Marlin barrel this way.

On the other hand... I have performed Fire Lapping on a couple of guns now -- and it worked extremely well.

My own experience with fire lapping is.....
1. Only do the fewest rounds possible to remove the restriction/clean up rough spots.
2. Clean clean clean after with Soap and Water.
3. Clean more with soap and water.
4. Keep cleaning with soap and water.
5. Shoot about 30 rounds standard ammo, clean per regular schedule.
6. Clean clean clean clean.
7. Work up new reloads to compensate for lower velocities.

Thanks

John

[wiljen]

800-1600 grit clover compound jumps to mind.

[wiljen]

800-1600 grit clover compound jumps to mind.

[machinegun]

After several dozen patches (only a few out the bore) using JB compound and the traditional cleaning, I was able to get a three shot group down to .392" using 42 gr of reloder 15 pushing that 280 gr cast boolit.
The more powder I used above 42 gr the larger my group got. But still, my worst groups now are as good as my best groups two weeks ago.

[machinegun]

After several dozen patches (only a few out the bore) using JB compound and the traditional cleaning, I was able to get a three shot group down to .392" using 42 gr of reloder 15 pushing that 280 gr cast boolit.
The more powder I used above 42 gr the larger my group got. But still, my worst groups now are as good as my best groups two weeks ago.