Borescope pics after re-bore

[mattri]

Had an old Marlin 336 30-30 re-bored to 38-55. Was having some leading issues so picked up a boresope to check things out. Sorry for the poor pics:

 

[358WCF]

I wonder if Tubbs final finish bullets will help that, if they go that big?

NECO used to sell fire lapping kits too, again not sure of sizes available.

 

[swimster]

How about shooting some jacketed bullets till it smothes up.

 

[mattri]

Good suggestions thanks. Little disappointed that it came out that rough. Contacted the guy that did it and he basically didn't believe me. I offered to send him the pics but he wasn't interested. Guess it explains the leading anyway.

 

[nicholst55]

If you need to fire lap it, try Veral Smith at LBT for supplies. He should have everything you need. I'm interested in who did the rebore, if you don't mind sharing.

http://www.lbtmoulds.com/

 

[mattri]

A company that specializes in exactly this. I'll PM you the info.

FWIW they seem to have a good reputation and came highly recommended on the cast bullet forum, a big part of why I went with them.

Even if 99.99 of the barrels they turn out are excellent someone has to be .01, guess it was my lucky day.

Will look into fire lapping.

Just thought the pics were interesting.

 

[McFred]

How's it shoot jacketed? If it shoots jacketed satisfactorily, then the cast load is on you, otherwise if you wanted a Bartlein, why didn't you get a Bartlein? I've seen factory Savage, Remington and CZ barrels that look worse than that and shoot just fine.

 

[mattri]

Doesn't shoot as well as it did before the rebore- haven't tried jacketed, no interest in using them in this rifle.

Didn't know Bartlein rebarrelled old 336s, guess I missed the boat on that one.

 

[sean68]

That looks like a 3 groove rebore that looks just like the ones I have had done by the same guy. I don’t think it looks too bad. He does not lap them as far as I know. I have no leading on my 336 38-55 rebore. I shoot cast bullets exclusively in cowboy silhouette rifles and get no leading on old factory bores that look much worse than that. I would try a larger bullet diameter or a different alloy or use a gas check if not already or less velocity or different powder or different lube or different mold etc. If you don’t get anywhere you can firelap like others suggest. I don’t know how much you have tried but I wouldn’t give up on it. I bet you can get it to work with cast.

 

[biggun2869]

Midway sells a kit of 3 tubs of different grits. I've got some and it works. Made by Wheeler

 

[mchees1]

If you do fire lap be aware that your lands will also erode away. If your jump to the lands is important, fire lapping will certainly chase them down the barrel. I used the Tubb kit with 3 different grits and did a .308 Savage barrel a few years ago. Fire lapping chased the lands 0.156" down the barrel so I ended up with a lot of bullet jump. The barrel looked nicer but it was a ton of jump.

 

[MGYSGT]

Gas check your bullets

 

[mattri]

Thanks for the replies.

Barrel slugs at .377 so have been using bullets from .379 to .381, gas checked and non with various lubes/coatings and alloys from 10-20bhn. Nothing seemed to help- which is why I got the scope.

I'm not here to bash the work, which is why I didnt name names- again I could have just got the only rough barrel he's ever sent out- who knows?

Don't like the idea of firelapping for the reason mentioned above, it wears away at everything indiscriminately.

Will keep working with it, again just thought the pics were interesting. Thanks.

 

[butchlambert]

I am not a fan of fire lapping!

 

[Twicepop]

I used to hang out with an old guy that re-bored and re-rifled many old black powder barrels. After re-rifling them he would lap the barrels with a lead lap coated with a slurry of very fine abrasive powder and heavy oil. To keep the hand work to a minimum he made a mechanical lap that had a low speed electric motor with a big wheel with several holes drilled from the outside edge to the center. The holes were to change the speed and stroke the jointed arm the lap was attached to. He always lapped these from the breech end to avoid destroying the crown at the muzzle end. He was a machinist by trade, before he passed he made several revolving carbines from S/A .22 pistols for his grand kids.

 

[Will Henry]

In truth, that does not look that bad. If it was mine, I would polish the bore using extra-fine steel wool and J-B, wrapped around a jag. If I wanted to do a more proper job, I would cast a lead lap and lap with 400 grit Clover compound. If the bore is dimensionally OK, the first method will work fine. When polishing this way, about fifty strokes should do. WH

 

[watercam]

Isn't 400 grit a bit too fine? The barrel maker I work with uses 240 for both stainless and carbon.

 

[sean68]

Thanks for the replies.

Barrel slugs at .377 so have been using bullets from .379 to .381, gas checked and non with various lubes/coatings and alloys from 10-20bhn. Nothing seemed to help- which is why I got the scope.

I'm not here to bash the work, which is why I didnt name names- again I could have just got the only rough barrel he's ever sent out- who knows?

Don't like the idea of firelapping for the reason mentioned above, it wears away at everything indiscriminately.

Will keep working with it, again just thought the pics were interesting. Thanks.

You went up the scale plenty far on size. Maybe try .378. I have had success at just .001” over on some guns. My Marlin cowboy 38-55 has a groove dia of .380 and really shoots well with a .381 with no leading.

 

[WayneShaw]

I've chambered quite a few barrels for cast shooting, including my own. Even though I polish the leade, you can't get everything. I always suggest a one shot and clean with a jacketed bullet, when clean do another, until it comes clean. I think some cast shooters don't know about copper fouling and ammonia cleaning, but any shooting to smooth things out are a benefit. Plus, it won't hurt a thing down the bore either. You never know. That's what I do.

 

[68W40 Retired]

That looks just like every barrel I ever got back from JES. It usually take 100-150 rounds fired to smooth out. Wayne York laps his barrels with a homemade lapping machine. The cost is about $100 more than JES but one does save money on lapping ammo.

68W40