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We had this debate once regarding deformation and how much pellet surface area is in contact depending on pellet size, but my squishy brain can't remember when, or what Don (and science) decided frown
I'm thinking smaller pellets have more surface area abutting the neighbor pellets, but am a victim of K through post-graduate education in the great state of Missouri wink

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Drew;
As promised, data on 16ga Lefever choke.
Gun = H grade SN 62,596 with 1907 patent date so one of the later ones though no indication of an Ithaca build. 28" barrels of "Best London Twist". Bores both measure 669" to within 4" of the muzzle. Choke taper begins here & ends @ 634" R (035" choke) & 632" L (037" choke).
Both chambers will take a .732" chamber gage to 2 3/4" (Current SAAMI Minimum chamber dimension for 16ga) I had thought I had previously determined the chambers actually measured to 3" which could be accounted for if they were just more than 001" undersize at forward end, though this may have been in error. They are at least a full 2 3/4" & not the usually expected 2 9/16" for 16ga.


Miller/TN
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I seriously doubt if shotgun pellets will be deformed after leaving the bore but I do recall this happening to a ML rifle which was tested years ago by the NRA. It was fired with pure lead round ball & both muzzle & down range velocity measured. With all powder charge increases the muzzle velocity increased but at some point ( with heavy charges) the down range velocity dropped. They accounted for this from deformation of the ball creating increased drag. Part of this deformation may have occurred in the barrel but they felt part of it was due to the force of air drag.as well. This was of course from a much higher velocity than obtained in a shotgun.


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Stan, thank you for your post. I also read of another individual testing 3/4oz loads in a 12ga. He said because the pellets in the bottom of the load were not deformed [ less set back ] the patterns were too tight at skeet ranges. He had to use fiber wads to open them up. I've opened up quite a few SxS's and the Remingtons seemed to have the longest total choke area - some were 7" with the last 1 1/2" parallel.
Years ago V.M. Starr wrote a small book about jug chokes. He use to shoot turkey shoots where the most BB's in a playing card would win. He used a muzzle loader shooting against cartridge guns and cleaned up - many competitors would not shoot against him. He opened up the bore 8" to 2" back from the muzzle leaving the last 2" parallel. This would allow him to still easily load the gun. I've done the same thing on guns when I wanted more choke. It works very well.

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I am not thoroughly convinced that shot doesn't react as much as a Semi-Solid as a Semi-Liquid when traveling down a barrel. I distinctly recall having read that in the early days of choke boring many barrels which were rather thin toward the muzzles had a problem of "Lifted Chokes", IE a bulge at the choke. This was not confined to the use of very large shot either. This would seem to indicate a Checking, rather than a speeding up of the charge. This seems to have been Fixed, by a slight beefing up of the wall thickness in the choke area. I have measured a good number of fairly light weight barrels in which the smallest diameter of the barrel was Ahead of the choke with a larger diameter in the choke area itself.
Also Burrard reported on some tests run some years ago in England wherein loads were measured for pressure, recoil & velocity simultaneously. Velocity was of course at this point of course the "Observed" velocity over 20 yards. A specially prepared barrel was made with a screw on forward end carefully lapped in to same diameter as the bore except one extension was cylinder & the other full choke. Length & weight were made identical. A definite relationship was recorder that the full choke gave a slight increase in velocity over the 20 yards, but also produced a slight lowering of recoil. This would definitely seem to be contradictory as the higher velocity should produce the heavier recoil.
This was explained by the cyl bore actually producing the higher muzzle velocity, but the quicker spread of the shot exposed each pellet to individual drag much quicker than from the full choke. The shot from the full choke reacted much more as a single projectile just long enough for them to exceed the velocity of the shot from the cylinder bore.


Miller/TN
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Thank you Miller.

One more; a SAC 0 grade 16g
R: 3 1/2"; .660" to .633" = .027
L: 3"; .660" to .630 = .030

I can not recall measuring any U.S. maker's choke constriction that did not have a short parallel section at the muzzle, but certainly have not measured them all.

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Drew;
None of my Lefevers have a parallel, they are all strictly taper. If you find a Lefever with a parallel in the choke you can pretty well rest assured it has been opened.


Miller/TN
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Thanks again Miller

Now could someone PULEEZZZ see if their Aubrey/Meriden bore is tapered from breech to muzzle, or just has a taper choke without parallel smile

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Drew;I do not have an Aubrey/Meriden to check. Here is the way the Lefever choke is described in their 1889 catalog & seems to have remained essentially the same for the rest of their existence:
""Boring Guns
After many experiments and Long experience in choke-boring, we have adopted the taper system, having proved beyond a doubt it gives the most evenly distributed pattern and greatest penetration. Being a taper from breech to muzzle, all sizes of drop-shot pattern about equally well, and with our full choke guns an average of 75 percent of the entire charge can be made in a 30 inch circle at 40 yards with all sizes of shot from No 8 to FF.
Possessing this quality renders our guns invaluable for both trap & duck shooting.""

Only problem is I have to date not seen a Lefever so bored. Mine have a taper from Bore to Muzzle, but NOT from Breech to Muzzle. I am not even sire just how in 11889 they would have achieved a taper for the full length of the barrel.
I have serious doubts they could have successfully made & used a full length reamer. About t5he only way I can come up with is they would have had to step ream & then join the steps with short tapered reamers & blend them all in. I have serious doubts this was done & would doubly doubt it on a gun in the price range of the Aubrey. I have little doubt it has essentially the same "Taper Choke" as does the Lefever.
Note I am not saying that Lefever was necessarily deceiving their customers, the Ad writers may just not have known whereof they spoke.


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Personal observations:

The Ithaca chokes I have measured have little to no parallel, and as a group have generated the better patterns. Period.

The shortest chokes I have measured (0.75-1.0" taper) were the work of a highly rated aftermarket supplier. As a group they have produced the poorest patterns.

Reclaimed shot. When I reload new shot, some of it always ends up on the bench, rolling every which way. Stray reclaimed shot hits the bench and stays put - doesn't go anywhere. The takeaway is that the deformation didn't happen when the shot hit the ground, or when it left the barrel, but rather in the barrel. It left the barrel deformed, every piece guaranteed to have at least one flat spot.

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