Plastic fouling in rifled slug bbl

[Cabin4]

Is there a cure or something that minamizesr plastic fouling in the rifled bbl ?  

I have 2 rifled slug guns, one is a 12ga and the other a 20ga. The 12ga is not a problem. The 20ga is a problem after about 4 shots the goups scatter and I mean scatter ! The first 4 shots are great stuff like 1 to 1.5 inch at 50 yards off the bench. 5th shot 9 inches to the right, 6th 8inches low, ect, ect. Clean the bbl real well and it all starts over again. Very strange. I did this 3 times today.

The 12ga I'm shooting the same winchester and federal sabot loads as in the 20ga of course for thier respective chambering. The 12 ga shoots incredible groups of 1.0 to 1.5 at 100 yards all day long without any cleaning during the shooting session.

Anyone have a clue on this and why the 20ga is so sesative to the plastic fouling ?

Thanks

[Slug-Gunner]

Your 20 gauge barrel may have a "roughly" finished barrel. Try running a rough cotton patch down the barrel with a swag and then shine a bright light in the barrel and see if you can see pieces of the cotton lint caught in the rifling. If so, the rifling is "rough cut" and may need some "polishing" to smooth it out. This can be done by using a small amount of "superfine" valve polishing compound on a patch and running it up-and-down the bore several times, and then checking it with a clean cotton patch. Continue doing this until the cotton patch no longer leaves traces of lint in the bore.... or by buying some of the "fire lapping" kits and using it on your bullets (although this is a little difficult with shotgun slugs).

Go to some of the hunting or gun web sites and do a search for "fire-lapping" a new barrel. This is a technique sometimes used to break in a new barrel and get the utmost in accuracy out of it. For some guns it seems to be a "miracle" and for others there is little change.

   :eek:  :lol:  :-D

[Bob_K]

I agree with Slug-Gunner that the 20 ga barrel probably has a rougher rifling finish.  I don't recommend valve grinding compound though.  You might try J&B Bore Paste which is a non-embedding polish specifically made for rifled barrels.  Brownell's carries it, among other places.  After that, you may want to use one of the high tech lubes on your barrel such as Tetra-Lube.  The micro-sized teflon particles are supposed to fill the pores in the barrel to reduce fouling, according to the sales brochure.  I found some improvement in reducing fouling in highpower competition rifles using these two items.