Boolits for Fire Lapping.

[GregLaROCHE]

I’m getting ready to try fire lapping on a couple of rifles. It seems that the best way is to coat jacketed bullets with grit. I don’t have any jacketed bullets for the calibers I’m planning to lap and I don’t want to spend the money on some especially, if I’m only using them as a support for grit.

I have a choice of range scrap that runs around 12-14 if not water quenched. I also have a small amount of linotype, that I don’t have any real use for, so I could cast some boolits with pure linotype. What would be the best to use as a support for the grit? I can also PC boolits. How would that work?

All ideas and recommendations appreciated. Thanks

[Three44s]

Soft lead is said to be best and silicon carbide lapping compound from NAPA (Clover leaf brand)

Beartooth Bullets has a book out which covers the process and I believe much of it is also online.

Three44s

[tomme boy]

Just remember that you only want the bullet to exit the barrel. So load them very light. I use 0.7gr of bullseye in my 9mm pistols I have done.

In a rifle I would try about 3-5grs of bullseye. This is with lead bullets not jacketed. Use old junk brass and pitch it when done. Just make sure you are at least 0.002" over bore.

[GregLaROCHE]

I was wondering how much of a charge. Makes sense a slower moving projectile will be more effective.

However, I don’t understand the need to pitch the brass afterwards.

[Mr Peabody]

The lapping compound gets impregnated in the case mouth. Beartooth Bullets system works very well and it's affordable

[Bent Ramrod]

I use unlubed, unsized cast boolits rolled in Clover 320 between two steel strips. I take one or two cases, a re/decapper, a powder measure set to a light charge of some powder like Unique, primers, tweezers and a dowel to seat the boolits in the barrel throat, a bore brush, and lots of cleaning patches and solvent.

I thoroughly clean after every five lapping shots. All the leading must be removed from the barrel and all the grit from the chamber. After 25 or so, I’ll try a group with the most accurate load I’ve found for the rifle and see if the group is any tighter. Depending on results, I’ll do more lapping or stop.

Where to stop is kind of a judgement call. I’ve fired as many as 100 lapping rounds before deciding that this is “as good as it gets.”

My lapping cases are junked or saved for other lapping jobs. They’ll ruin reloading dies if they get mixed in with other cases.

[charlie b]

Just be aware that you may make your barrel oversize if you are not careful. You are enlarging the throat more than the rest of the barrel.

Lead does work best. Unless you are starting with a sewer pipe, finer grade compound is better.

I've seen it screw up more barrels than it fixes. Usually cause people want to get a hand lapped finish and they go too far.

[GregLaROCHE]

Now I have to think about this project. I understand that reusing the brass is not a good idea. I an in France and I have to pay between 1.50-2.00 dollars a piece for a 45/70 Starline cases. Unless, I sacrifice several old cases and keep going back to my workshop to reload them each time, this could get expensive. Anyway idea how many times needed to shoot them? I know it probably all depends.

[tomme boy]

Do you have a way to hand prime? If you do then bring that with you and a punch to knock out the primer. Now take a 9m or a .40cal. or 45acp case and use that as a dipper to measure out one scoop of powder. Dump that in the case and finger seat a bullet in the case. Carefully load it into the chamber and shoot it. Then just repeat.

[tomme boy]

Make sure to test the cases you are going to use to measure the powder. See what each will dispense of the powder of choice. In the 4570 I would error on the high side to make sure you can get the bullet out of the bore. I would shoot for 6-7grs of bullseye speed powder

[Winger Ed.]

Unless, I sacrifice several old cases and keep going back to my workshop to reload them each time, this could get expensive. Anyway idea how many times needed to shoot them? I know it probably all depends.

The official redneck way to do that is use one brass over and over by
using only enough powder to do little more than get the soft Lead slug out of the barrel.

Rather than going back and forth to the range,,,,,
wait until the wife is gone, and wrap a old towel that won't be missed around the muzzle a few times
and fire it inside the shop into something expendable at point blank range.

And so on and so on until you're done.
I've used old phone books or a stack of news paper to catch them,
but usually, the boolit is caught in the folds of the towel .

It won't make much more than a well muffled 'thump' kind of sound.
With the doors closed, even the next door neighbor won't hear it.

[GregLaROCHE]

Lucky I can shoot in back of my house.

[waksupi]

I always used plain ol' WW bullets.

[GregLaROCHE]

The more and more I learn about fire lapping, the more I start to think maybe it’s not what I want to do. I’m not thinking of a rusty and pitted gun. I think hand lapping maybe my best option to get a nice polish.

[charlie b]

Hand lapping is the best way to go. But, it has to be done properly and can easily mess up a barrel.

Fire lapping on the other hand is fairly simple. It normally won't completely ruin a barrel since much of the cutting action is in the throat, not as much at the muzzle. If screwed up by going to far you can still have the barrel set back and rechambered.

Both should be considered last results for improving a barrel that doesn't shoot well. It enlarges the dimensions of the barrel a bit and can enlarge it too much.

[tomme boy]

Thats why I only do the fine bullets. I also learned that when you think that you need just a couple more, STOP!!!!

[yeahbub]

You don't mention why you want to pressure lap your rifles. Are the bores inconsistent, showing loose and/or tight spots? Are they pitted and fouling quickly?

You may want to look into how abrasives are evaluated in France before you commit to lapping a precision instrument (barrel) without quite knowing how the abrasive was judged to be suitable. In the US, the grading of abrasives is not standardized, so one company's "fine" may be another's "medium" or "coarse", depending on its intended purpose. I have found some labeled "fine" which was too coarse for barrel lapping and felt like sand between my fingers. It would have ruined a barrel pretty quickly. Numbered abrasives are another matter, graded for particle size, how aggressive it is and the material it is suitable to be used on. You can take a look here and find out a bit more: https://www.us-products.com/Articles.asp?ID=265 Having pressure-lapped a gaggle of rifles over the years, I have settled on using usually just two grit sizes for barrels in good condition, US Products Crystolon 400 for smoothing tooling marks in throats and lands which accumulate copper or lead quickly, and Crystolon 600 to finish. For corroded or pitted bores which foul fast or those with tight and loose spots, I have started with Crystolon 320 and slugged them every five rounds or so until the bore is consistent and then moved to the finer grades. It's better to start with a finer grade than too coarse. That way, the wrong grit will have done no damage.