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Joined: Feb 2006
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Sidelock
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Sidelock
Joined: Feb 2006
Posts: 3,763 Likes: 68 |
Miller, very interesting. Do you have the % for the other chokes, IC, MOD, IMP MOD.? Also how long ago did someone figure this percentage, was it patterned like we would do it now?
David
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Joined: Jan 2002
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Sidelock
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Sidelock
Joined: Jan 2002
Posts: 13,386 Likes: 1323 |
The "Old" 12 gauge standard for full choke was a 10% to 11% reduction in bore area for the choke. This gave a constriction of from .038" to .041". This same % of reduction in the .410 would give constrictions of from .021" to .023". I understand the percentage thing for different bores, but where was this "Old 12 gauge standard" devised, or originally decided/deduced? It's interesting, and I don't dispute it, but I've never seen it written before, that I can recall. SRH
May God bless America and those who defend her.
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Joined: Dec 2001
Posts: 7,084 Likes: 462
Sidelock
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Sidelock
Joined: Dec 2001
Posts: 7,084 Likes: 462 |
I have never heard it expressed as a percentage of bore diameter but I certainly have heard of .040" being the old standard for full choke in a 12 bore. The Brits often expressed choke as 1/4, 1/2, 3/4 with each 1/4 being .010" of constriction.
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Joined: Feb 2004
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Sidelock
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Sidelock
Joined: Feb 2004
Posts: 13,880 Likes: 16 |
I had a sxs Ugartechea that had .021 chokes. It was pretty tight patterning. One gun I have has been altered to cylinder bore on the right barrel, so I relieved the forcing cones to about 3" cones and polished them. The gun shoots more evenly dispersed patterns than any other 410 I own. This bore actually holds together for some decently long shots. It's my favorite quail gun. One gun I have with standard cones and full chokes has excessively hot cores in the patterns. My recollection is that Briley calls .020" a full choke in 410. I have one 410 gun that has a .035 choke. It patterns ok.
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Joined: Feb 2006
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Sidelock
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Sidelock
Joined: Feb 2006
Posts: 3,763 Likes: 68 |
Thanks Chuck, the more you ask about choke constriction for .410's the more answers you get. Now with yours I have seen .022 to .035. The pattern board will tell. I think I will start at 30 yards at a 30" circle with a 25" circle and a 16" circle inside of that, and then go to 25 yards with the same configuration and see.
David
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Joined: Jan 2006
Posts: 9,526 Likes: 354
Sidelock
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Sidelock
Joined: Jan 2006
Posts: 9,526 Likes: 354 |
Sport with Gun and Rod in American Woods and Waters by Alfred Marshall Mayer, 1883https://books.google.com/books?id=IJcCAAAAYAAJ&pg=PA781&vq The choke-bore now almost universally adopted by gunmakers is as follows: Taking a twelve-gauge gun as an example, the construction of the bore from the front of the breech-chamber to within one and a half inch of the muzzle amounts to about 1/100 of an inch. At one and a half inch from the muzzle begins a sharp contraction which, in the length of one inch, equals 25/1000 of an inch. The last half inch of the bore is a true cylinder. .010 + .025 = .035" constriction = 5% for "choke bore" .410" X .05 = .0205" The Gun and Its Development by W.W. Greener, 1907 http://books.google.com/books?id=3HMCAAAAYAAJ&pg=PA416 The various degrees of choking may be classified as: Full-choke, which, with a 12-gauge gun, standard load, distance and conditions will make an average pattern of 215 pellets The half-choke (same conditions) ... 185 The quarter-choke... 160 The improved cylinder... 140 The old cylinder…115 Any better average shooting than 215 may be termed an extra full-choke; the improved cylinder is a barrel very slightly choked. Unfortunately, Greener doesn't define his "standard load". If it was 1 1/8 oz. No. 7 Tatham chilled shot (291 per oz.), then 1 1/8 oz. = 215/327 = 66% for Full-choke On p. 354 he states 1 1/8 oz. No. 6 is 305 pellets. 215/305 = 70%https://books.google.com/books?id=3HMCAAAAYAAJ&pg=PA354
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Joined: Feb 2006
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Sidelock
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Sidelock
Joined: Feb 2006
Posts: 3,763 Likes: 68 |
David
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Joined: Dec 2001
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Sidelock
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Sidelock
Joined: Dec 2001
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I don't really know where I got the percentage thing, I think I just devised it working from stated as well as measured diameters of chokes in various gauges.
It could be a bit easier to say % of choke area in relation to bore area. Let B = bore diameter, C = choke diameter & R = % of reduction. The formula then is C = √(B˛ x R) Thus for the 12 gauge √ of (.729˛ x 90%) = .692 or .37" of choke constriction. For the .410 bore √ (.410˛ x 90%) = .389" or .21" of choke constriction. These would be essentially full chokes.
Miller/TN I Didn't Say Everything I Said, Yogi Berra
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Joined: Feb 2004
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Sidelock
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Sidelock
Joined: Feb 2004
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David, In my opinion, 30" is way too large a k8lling pattern to expect. An 18-20" killing pattern is realistic.
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Joined: Jan 2002
Posts: 13,386 Likes: 1323
Sidelock
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Sidelock
Joined: Jan 2002
Posts: 13,386 Likes: 1323 |
David, In my opinion, 30" is way too large a k8lling pattern to expect. An 18-20" killing pattern is realistic. I fully agree. You have to keep remembering density. Density is what kills. Density is what gives multiple hits, contributing to the all important factor of pellets hitting vitals. Density with a .410 pattern means a smaller overall diameter. SRH
May God bless America and those who defend her.
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