doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Choke length

It doesn't. See "Sporting Shotgun Performance," by Dr. A. C. Jones, page 58, Figure 41. Neither does a parallel section.

Shot is at least a semi-fluid and subject (pretty much) to the laws governing fluid dynamics. Shot flooooows through the forcing cone and the choke. It does not smash into these constrictions. Rather, it flows through in an orderly fashion. Deformation occurs at ignition and early acceleration.

DDA

"Deformation occurs at ignition and early acceleration."
Rocketman, I have to disagree with you about that especially with todays plastic wads. Shot is still in the wad and deformation would not occur until after it left the barrel

A.J. Aubrey had this all figer'd out in 1908

"choke bored on the taper system"
1908 Sears, Roebuck & Co., Chicago, Ill. Catalogue No. 117:

I would very much appreciate if someone with an Aubrey would measure the bore and see if it tapers the full length.

"the choke is bored from breech to muzzle"



Daryl Hallquist has confirmed that an occasional Lefever 12 gauge has bores tapering from the breech to the muzzle (.756 to .708 left and .715 right on one gun). Most have a standard U.S. .729 - .732" parallel bore.

Starting in 1907, Hunter Arms catalogs included the following statement:
"All Smith Guns are bored full choke unless otherwise ordered. We bore all our guns according to our Multiplied Choke Bore System, which has made the Smith Gun famous the world over for long-distance, close-shooting and hard-hitting qualities."

LRWF marketing verbiage in 1923 "A distinctive L.C. Smith method of choking adds 15 to 20 yards to ordinary shotgun range...specially bored to a longer, tapering choke..."
LRWF have bores of .730" without tapering to the choke constriction of about 3 inches in length; slightly more than the standard constriction over about 1 1/2" with a 1" parallel at the muzzle. As noted, some have no parallel section but taper over the length of the constriction.

Probably merits a topic all its own. I don't think all deformation on ignition is eliminated by plastic wads. Reduced for sure, but not totally eliminated.

And why would deformation occur after the shot leaves the barrel? Pellets running into each other?

Interesting subject.

Drew;
I have spoken with someone on these Lefever chokes, don't recall now if it was Daryl or perhaps Bob Noble. While it was true the bores were not totally cylinder all the way the majority of the restriction was still at the muzzle. The bores themselves did have some taper in them but not uniform. The dimensions which were given to me seemed as much as if it were just uncorrect reamer wear as any actual intentional thing. I have several Lefevers from an early side pivot up to an Ithaca assembled one & none show any significant taper to the bores, all have the taper choke at the muzzle. No parallel with full choke running up to around 4" in length.
I do not have a gun so bored to prove it, but am of the opinion that a barrel with a constant taper from chamber to muzzle would shoot pretty much cylinder as a cylinder, rather than as a choked gun.

David, your theory has been proven to be incorrect by science. Read this post I made last spring after speaking with Tom Roster over the phone concerning patterns. This is post #441238. The entire thread is very good, except for Wonko's rudeness.

"I spoke at length with Tom Roster this afternoon by telephone. I was really appreciative, and little surprised, that when he answered he took the time to talk, but he did. I asked him if anybody had ever done scientific testing on lead shot loads to determine if lead shot deformation, due to setback at ignition, was greater in any area of the shot load than any other area. I told him I thought I remembered reading about some such testing many years ago, and had searched the 'net for the last several days trying to find such, but had struck out. He said that someone had indeed done that, about 30 years ago, and that someone was him. What he did was basically this: Tom, who doing a research paper at an institute of technology somewhere, painted lead shot, from the same bag, three different colors. He then loaded it into a regular shotshell load in three layers ..... one color for the bottom third of the shot column, one third for the middle, and one third at the top ... each layer a different color. He then fired the loads (more than one) into a tank of water. (He paused to remind me that water will NOT deform a lead shot pellet when fired into it). Then, he recovered the pellets and segregated them by color. He said it was VERY obvious that the pellets that were on the bottom of the load were much more deformed than the one-third layer above it, and that the top third were the least deformed.

I had remembered reading about this test long ago, but could not put a finger on who did it and when, could not find evidence of it on the 'net, so did not mention it earlier in this thread. It just so happens that the one I called was the one who actually did the testing. Tom said the tests were not ON the net, because the net had not been invented when he did the tests, and he had never put the results on there.

He went on to tell me about two other tests he had done concerning lead shot pellet shape ballistics, but they do not pertain to this particular issue.

I refused to discuss this with the arrogant, and ill mannered individual who has replied several times here, but this may be interesting to some other cogent, and truly, sane board members here. What the other individual thinks of it really doesn't matter to me.

SRH"

I'm no scientist but the theory of deformation after the shot leaves the barrel sounds silly to me....

And as far as choke length most modern gun manufactures are making their chokes longer and longer for a reason.

I just bought a Browning 725 with the Invector DS chokes and they are really long.

I should have been more descriptive in saving that the shot in my opinion would be more deformed after it was leaving the wad, which would be by this time out of the barrel.

Stan, I can believe what Tom had written after his experiment, BUT if memory serves me, I recall reading about the shot in the bottom of the shell over-taking the shot in front of it. Actually almost like pushing it out of the way. I wish I had copied that article or remembered where I saw it. This was not too long ago and it might have been from either Batha or Gil Ash and I'm leading more to Ash.

Pellets recovered from mallards at 45 yds. Ed Lowry, "Shot Penetration in Soft Targets", American Rifleman, Oct. 1988



Probably not worth the $25, but it appears "shot packing factor" is the issue
https://www.astm.org/DIGITAL_LIBRARY/JOURNALS/FORENSIC/PAGES/JFS11154J.htm

Bob Brister's illustration
http://www.classicshooting.com/blogs/com...easant-shooting

Brother Drew, Bob Brister's link is another great point on the amount of antimony. That slipped my mind and now makes it interesting on when some of these tests were taken and when antimony first started being used. This could explain a lot.
I have read from the different shot manufacturers on what their antimony content is and most seem to be in the 4-6% content but starting at #4 shot the antimony is very little. That would make sense as it would be harder to deform than #8's.

It would be interesting to note what happens to shot in a wad once the trigger is pulled. How long it is together before separation?