doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com INTENTIONAL PITTING OF SHOTGUN BORES

I have a bunch of smallbore .410s. I don't think I'll be able to piss down the barrels until I'm as old as AmarilloMike.

Mike
I've also read that some shooters pissed down their gunbarrels to purposely pit the bores with the belief that rough bores improved pattern performance. This was a long time ago; and like you I can't recall the source, but I only remembered this bit of trivia because I found this practice so foreign to my personal views.

Chuck I have seen you shoot. You couldn't even hit those barrels on the outside, much less the bores.

But on our next hunt bring all those girly gun 410s and I will help you out!

topgun - same as the story I heard.

Ralph T. Walker, "Shotgun Gunsmithing" stated that he deliberately tested roughing up the chokes, and the patterns diminished, then really smoothed them up and the patterns improved. His reply on the matter "those who think a rough choke improves patterns should go shoot some and learn." I rather think that the slits in polychoke types retards the wad better than just a rough bore. but then, the discussion goes round and round. As concerns pitting a bore, I say that is madness. Steve

This 'retard the wad' urban myth is, well, retarded.

Think about it.

There's positive pressure all the way up the barrel, even at exit.

The pressure is behind the wad, and the whole payload is accelerating right up to muzzle exit.

How can you 'retard' (slow down) the wad and still accelerate the shot?

Choke effect is venturi effect. As measured by a chronograph full choke velocity of the leading pellets is faster than cylinder bore due to choke effect and not some impossible retardation of the wad.

I do have serious doubts that patterns are going to be improved by roughing up the choke. As to slowing the wads though it must be understood this is a "Relative" term. This can be well understood as a slowing of the rate of acceleration. The shot itself would not be so much affected by the roughness as the wads, thus would retain their velocity. "If" we were speaking of roughness all the way down the length of the bore then yes, if it slowed the wads it would slow the shot as well. If however you slow the rate of acceleration of the wads in only the last 1"-1�" you will not affect the velocity of the shot by much. To prove this either way would take some very extensive testing, including high speed photography of the shot exiting the muzzle to see for certain if this roughness did indeed prevent the wads from disrupting the base of the shot charge. This would it would seem to me to be mostly a moot point with plastic wads with shot cups anyway.

Ed, Shooting Facts & Fancies by Gough Thomas covers the subject. He wrote from the perspective of an experimental engineer. His concluding paragraph on the subject reads:
'So, a gun slightly pitted, and throwing, maybe, slightly wider patterns than it otherwise would do, may yet prove the better gun for work at moderate range. But the ideal is still the immaculate bore, throwing patterns of the best possible quality, of the highest attainable pellet energy, and of the right spread for the work in hand. As we press for longer and longer reach, the nearer we can get to the ideal the better.' Lagopus.....

Miller I think my reasoning is perfectly sound on this one.

If you slow the rate of acceleration of the wad, you also slow the rate of acceleration of the shot charge. The wad is pushing it to ever higher velocity and without a push it will go no faster (Newton).

Note that we are not decelerating. Positive pressure is present until the barrel is vented to atmosphere at the muzzle.

It's well known that barrel length does affect velocity to the tune of about 15-20 fps per inch, so that proves continuing acceleration.

The 'retarding' or 'stripping off' concept is bunk, cherished lore though it may be.

Sounds like a good sales gimmick. We need all we can get.

As for the advantage of longer shot strings, David Trevallian told me of an 1885 Purdey with extra barrels that was a live bird gun in 20 Ga 3 1/2"! That shows that long shot strings were tried a longtime ago.