Tubb final finish bore polishing system

[cbourbeau32]

I saw a message yesterday where the "Tubb final finish bore polishing system" was discussed and there was some concern as to the possibility of it not working very well in "micro groove rifling". Is that the type rilfling that the handi has? Has anyone ever used that system? Midway USA has the final finish bullets for most calibers for reloaders and quite a few calibers in already loaded rounds. Thanks, Charlie

[Pennsyman]

Micro-groove rifling is common to Marlin firearms. I'm not sure of the exact groove-land count but it's near double standard rifling which is usually 6 grooves. Handi's have the normal 6 groove rifling.

[cbourbeau32]

So based on the handi having standard groove rifling then it should be safe to use the fire lapping system then right? Charlie

[quickdtoo]

If any of you slug an NEF bore, you'll see how shallow the rifling is, one person has already tried the full Tubb's treatment and ruined the bore, after the treatment, he got key holes, I just tried to find the post to no avail, I wouldn't recommend using it unless you only use the finer grits, I had one for my .338-06 Ultra, but never used it, the 2 coarsest grits are very aggressive, too agressive for even the cut rifling in the custom bore it has IMO. Tubb's now only comes with 40 bullets instead of 50. I believe lapping the bore with a lead slug or just polishing it with one of those mentioned in the FAQs is all that's necessary and has worked well for me in about 30 barrels so far, as it has for many, many others here.

Another issue is that a lot of NEF bores are slightly oversize, you'll find that out also when you slug the bore, even removing the .0003" that Tubb's says it will remove may be detrimental to accuracy.


I did find a post where the shooter used 320 grit and improved the accuracy in his BC.

Tim

http://www.graybeardoutdoors.com/smf/index.php/topic,81841.0.html

http://www.jarheadtop.com/article_finalfinish.html

[cbourbeau32]

Thanks Tim, I looked and the rifling isn't very deep. What do you think of the 3 grit compound they sell on MidwayUSA? Do you just put a patch in the swag and put the abrasive on it and push it up and down the barrel about 50 times with a guide to keep the rod centered, cleaning between grits? What is the technique for the lead slug procedure? Have you reloaded your 7mm 08 yet? Thanks, Charlie

[quickdtoo]

Don't know anything about the Midway stuff, I've only used the polishing method with either a patch on a jag, or tight bore mop.

Basically To make a lead slug lapping rig, you need a steel rod of sufficient stiffness for the bore, I've only done it one time, used a  ¼" rod, centered in the bore near the muzzle with patches around it, warm the bore and rod with a heat gun, then pour hot lead in the bore to form a lead slug on the rod that conforms to the bore, then use lapping compound on the lead slug and stroke the bore with it. There are other ways of doing it, as I said, this is the only way I've done it, and only once on a custom muzzleloading barrel.

Tim

http://yarchive.net/gun/barrel/lapping.html

[Fred M]

Well, if you want to make a mess of your bore just go ahead with your three grit system.

What makes you think your barrel needs lapping, some polishing with Flitz
yes.

Fire lapping is used only on the worst kind of barrels. A button rifled barrel like the H&H don't need lapping. If it does then there are very few handy home shop gun smith qualified to do it or have the know how.

The systems sold by Tupp and other are poor excuses for getting better accuracy.
The NECO fire lapping kit is perhaps the best one, and comes with a booklet of complete instructions. It also comes with the appropriate size of soft lead slugs to suit the caliber you want o lap.

These slugs will help you to determen the amount of lapping required and the size of grit needed. In all cases fire lapping will move the throat forward.

In a halve decent barrel only the two polishing grits of 800 and 1200 are used with very low velocity loads of no more than 1400ft.