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

I recall reading years ago about the practice of intentional pitting of shotgun bores. the purpose was to make patterns as wide as possible for close bird shooting. the idea was to create a rough surface, so lead shot would be scored and thus fly in an irregular pattern...is this info in greener's book or else where? or did I imagine it?

Couldn't you have old Ed Lander just build you a blunderbuss?

Ed if that's so I must have a lot of guns previously used by folks who shot close birds...Geo

I believe I've read that some have experienced tighter patterns if the parallel at the muzzle is slightly roughed. Speaking of using shot cups, of course. Makes sense if choke helps pull the wad away from the charge.

Ed..I have read WW Greener The Gun & its Development at least twice,& can't remember anything to do with that.
Unless folks who didn't clean their bbls noticed a wider swath as the pitting developed..????
why wouldn't you just use some banged up, out of round type pellets (rejects) ?..instead of messing with the bores...it would do probably do something similar.
Kinda like that "Square/cube " shot thing a few years ago.
Though I like the last bit of the muzzle roughness idea, of retarding the shotcup, & letting the pellets fly out on ahead...
Joe...is that idea used/&/or accepted to work???..seems like it could/should
franc

Jack O'Connor

Many older trap shooters would roughen their chokes to retard the wad.
Some say Baker choke tubes have this effect.
Mike

John Singer wrote
I thought I would share the following with all of you.
I recently purchased an old book The Shotgun Book by Jack O'Connor. The book was published in 1965.

There is an entire chapter devoted to "The Choke in the Shotgun Barrel".

The following exerpts are from that chapter:

"This whole business of constriction is complicated by the fact that the surface of the choke itself has an important bearing on the density of patterns. It would seem reason reasonable to assume that the choke with a very smooth surface would pattern better than a rough one. Actually, just the opposite is true.

I first learned of this phenomenon from the late E. Field White, the inventor of the Poly Choke. His theory was that when the choke is glass-smooth, the wads are not retarded, smash into the rear of the shot column, and scatter the shot. On the other hand, if the surface of the choke is roughed up, the lighter wads are retarded, lag behind the shot charge, do no smash into the shot column, and do not disperse the patterns.

He also told me that it is possible to get full-choke patterns from a cylinder barrel if the barrel is long enough and a bit rough...

It is common for the pattern efficiency to fall off in trap guns that have been shot thousands of times until the choke portion of the barrel has been polished glass-smooth by the passage of the shot. Patterns are then brought back to full choke by roughening up the choke portion with emery cloth or by some other means. An engineer who was formerly head of the deprtment of research and development of one of the major manufacturers tells me that he found the condition of the surface of the choke to be almost as important in getting tight patterns as the amount of constriction. Experiments by Oberfell and Hompson verify the necessity for a slight Roughness of the choke for best patterns."
http://www.duckhuntingchat.com/forum/viewtopic.php?f=14&t=125212

as I recall, this intentional pitting of bores, in order to score shot was done prior to ww1 and before we had shot cups...

maybe I am just imagining this...

You didn't dream it ed. Somebody else may have but it is definitely in writing.

I have a book from a little known contemporary English shooting instructor that moved to the USA. He talks about some guys in England used to piss down their new barrels in order to pit them. He said the purpose was to make the shot spread. He said it was effective.

If I find the book and the quote I will post it.

I was half right.

"Successful Shotgunning" by Peter F. Blakeley, page 142

No mention of pissing down the barrel but he does talk about a badly pitted barrel with numerous poorly removed dents owned by a gentlemen named Will, known as a crack shot. Blakely's theory was that the effect of bore scrub opened the pattern and lengthened the shot string. Since he talks about bore scrub I think he was talking about cartridges without shot cups but he doesn't so state.

Franc, as memory serves me, I believe that is part of the choke system the Soviets used in their trap guns along with a type of jug choke behind the normal one.

(Sorry Ed to steal your thread.....didn't mean to.)

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.

Interesting report of a significant improvement in pattern density over time, felt by Greener to be from 'burnishing' of the bore. I understand we are discussing both non- and plastic wad protected shot
The Gun and Its Development, 1907
http://books.google.com/books?id=3HMCAAAAYAAJ&pg=PA353&source

Please note: I freely concede that others here are brighter, better looking, have more valuable shotguns, and have killed more birds behind better dogs; therefore in responding please consider Proverbs 18:2 and try to be helpful.

Some frenchman must have pissed a lot down my Darne barrels because by the looks of them they should throw a great pattern!

Drew stop that! You are so inconsiderate. How would we have any fun if everybody copped that attitude? You never think of others, just yourself.

Longer shot strings you do not want! Winchester super x loads were first touted as shortening shot strings and therefore improving the killing pattern. In the three dimensional cloud of shot, a duck passing through the rear of an extended string will more likely be crippled than killed cleanly. There will be fewer pellet hits. To those who think it increases the ability to hit passing shots at all, I say--practice instead. Just my two cents...Steve

Franc I've always liked you through the years. Your posts and contributions were and are always welcome as they bring a good degree of knowledge, honesty and unabashed inquisitiveness spiced with a nice dash of curiosity.

But my esteem for you has just risen upon learning that you are a man who has not only read the entire W W Greener tome once but "at least" twice! Now that's a sure sign of a man hungry for the right kind of knowledge.

As they would say in your native land, or at least in movies of that land, "Good Show!".

Jonsey;
Would you care to explain the fact that wads have definitely been known to be left in a bore while the complete shot charge was "Expelled". The Shot did not stop when the wad stopped. Its known as "Momentum/Inertia". The heavier weight of the shot gives it greater inertia than the wad. Now understand I'm not saying that in fact roughing the choke area a bit does indeed slow the wad, that's the theory of it. The Theory though is just as sound as your theory the wad cannot be slowed with out the shot being slowed an exact & equal amount. That theory Don't Hold no Water either. Note that the Vast Majority of the movement of a gun in recoil occurs after the charge has left the muzzle & the gun is given no more impetus to recoil. What has happened is that in that short period of time the charge is still in the bbl the gun has been given the Impetus to set it in motion & given enough momentum to keeep it in motion for some longer period of time than it is actually being pushed. According to "Newton's Law" if you fired a total charge weight of 1�oz (shot, wads & powder) down a bbl in which it could travel 30" & the gun weighed 7lb the while the charge was traveling that 30" the gun would travel 0.335" in the opposite direction. Now I doubt seriousl;y you or anyone else would question the "Fact" that gun will travel a lot more than .335" in free recoil, yet after that amount it is no longer being "Pushed" as the charge is gone.

An old time trap shooter I knew used to carry a bit of crocus cloth in his pocket. He would wrap it around his little finger and make a couple of turns in the muzzle of his trap gun. His theory was it roughened the choke slightly which produced a better pattern. Subsequent shooting he claimed, would smooth it back out and he would repeat the process. It was religion to him at a trap shoot. Whether it actually worked or not, I can't say. Trapshooters are well-known for a multitude of idiosyncrasies....almost as much as pigeon shooters.

You've described momentum well, 2-piper.

Understand though that I'm talking about a reduction in acceleration, not a reduction in velocity.

If you were to vent the pressure off prior to bore exit then not only would acceleration stop but deceleration would begin due to bore friction and air drag.

A powderless shotshell does exactly that. The wad sticks for the reason you've described.

A properly functioning shell though accelerates the payload all the way to bore exit and internal ballistic graphs show this well.

I'd rather read a discussion between Jonesey and Miller than eat when I'm hungry.



SRH

Jonsey;
Yes I fully understand we're tslking about a slowing of acceleration. Also Yes if the rate of acceleration of the wad is slowed that of the shot will also, "BUT" it is not a given that it will be an identical slowing. It is certainly possible for some External factor to have more influence on the wad than on the shot.

Stan
You're self control is high. I'm not going to make it thru this one

Chuck: Who reloads for your animated icon? It's not that old guy I shoot with Thursdays is it?

Stan: "The Collected Works of Miller" would sell well. A very practical guy who knows his stuff.

Miller: We appear to disagree. Which is unusual.

Greener: Most perfect patterns I ever saw. Rocketman would likely say they are too good to be true.

Skeetx: I read your edit and quote of the Polychoke guy. The full choke patterns from a (very) long and rough barrel makes perfect sense.

1. The length means the shot is no longer under acceleration by pressure behind the wad.
2. The roughness slows down the pellets in contact with the bore, elongating the shot charge. Same result as a choked barrel, different method.

G. T. Garwood: If you're an engineeer, show me your train.

A small post script. I'm currently using an ultralight load in an old Parker damascus barrel set. This is a 28" skeet choked barrel (about .003).

The load is 12.9 grains of AA Lite behind 7/8 oz. This is a very fast powder, and a very low charge weight. It chronographs 980 fps.

If there ever was a load that would provide acceleration only to a point short of the muzzle and should exhibit tightening of the pattern from the effects we've been discussing here, this should be it.

Alas, it still throws a skeet pattern.

Had vowed to never respond to a thread with a title IN ALL CAPS, but can't help myself.

The Winchester-Western Mark 5 with a polyethylene shot collar (not wad) was introduced March 1962. These images are at 1/2,000,000 sec of the ejecta of a Mark 5 Super Trap load from a full choke M12. At 36" the ejecta with the collar does appear to have fewer fliers and a slightly shorter shot string



which was advertised as producing a 10% 'better' pattern



The Remington one piece 'Power Piston' polyethylene wad was introduced in 1963 for target loads. Some argued that roughening the choke segment would 'retard the wad' so it wouldn't run into the shot column. These images at 1/1,000,000 sec. clearly show the wad rapidly falling behind the shot column. Unfortunately, I couldn't fine the original reference.



SO
1. protecting the shot from abrasion/flattening is a good thing
2. air resistance adequately retards the wad.

And per Greener, polishing the bore may improve the pattern for non-shot cup protected shot.


Please note: I freely concede that others here are brighter, better looking, have more valuable shotguns, and have killed more birds behind better dogs; therefore in responding please consider Proverbs 18:2 and try to be helpful.

I am of the bellief that a certain load will work better in a particular gun that others will, that is why I use them.
However, to roughen up a bore or intentionally pitting it to try and change the pattern is complete lunacy to me, and it's not the only things that has been professed in the past by people who knew no better or thought they did and could sell either an article to a magazine or something else they manufactured

How about shooting the gun with a load that works well with it to improve your scores?
THAT would be a bigger help than trying something that would ruin a bore and degrade a gun, but that's just my opinion.....
DT

Think about it??? Are you crazy? Think about it on this board?? You get a Gold Star For the Day for not having studied physics at Hogwarts.

Now if you could just quit w/ that venturi effect for chokes you'd be way cool.

have a day

Dr.WtS

OH wait. It's not venturi at all is it?

It's a simple vector problem, whereby the edge pellets are given an inward vector by the choke taper.

That's it. No matter the huge mass of shot inboard of the edge pellets that appear to be in the way.

OMG!!!! Someone understands. STAGGERING!! And they poke out the front of the column because there is no place else to go.

Double Gold Star for you today!! Actually you really deserved the Double for the "wad stripper as BS" comments anyway.

have a day

Dr.WtS

And this is different from a venturi, how?

FAAQ! There goes my double star...

The pressure in the constriction of a venturi .......?

The pressure in the compressed shot charge in a choke ......?
(Hint - hard shot deform less in a full choke)

The velocity of the fluid in a venturi ......?

The velocity of the shot charge in a choke ......?



Yes, you lose the Double but you have at least a good start.

have a day

Dr.WtS