chokes

[Old Bull]

hi guys i was just wondering me being fairly new to shooting could some one tell me what is the oppenest choke and wich is the tightest choke. i know that the 1/4, 1/2, 3/4, 4/4 but would like to know about skeet and improved cylinder ect...

[M.I.A]

It goes in this order Cyl, Impr Cyl, 1/4, 1/2, 3/4, 4/4. So cyl is the openest, and 4/4 is the tightest

 

Skeet is basically Cyl, and improved cyl is just a tad tighter than cyl but not as tight as 1/4 though many people refer to imp cyl as 1/4

 

Other terms: most open first, Cyl-Skeet, Imp Cyl, MOD, Imp-mod, Full

Edited September 14, 2011 by M.I.A

[welshwarrior]

That tad tighter is key the first few thou of choke make a lot of difference much more so than in the full 3/4 zone

[Guest cookoff013]

skeet is about .005" restriction. some different brands are even .007"

 

my merkel is choked full, but there is near a 0.055" choke on that. but the barrels are way overbored too !

[Old Bull]

cheers guys not thats cleared that

[clayman]

Choke is a function of the combination of the barrel restriction , the forcing cones, barrel wear, the cartridge type / load / shotsize, velocity / pellet hardness and wad type.

 

Its defined by the number of effective pellets in a 30" circle on a pattern plate at the standard test distance.

 

The designations on choke tubes are an APROXIMATION in theoretical terms as to what might be acheived.

 

There is some manufacturer and international convention variation in designation: ie some manufacturers make 5 chokes and declare Cy and Skeet as the same, while some have 6 with skeet being 1/8th choke, and even further some have 7 in a set with improved skeet at 3/16th! Additionally, super chokes exist - sometimes called turkey chokes - and these are "Over full" - tighter than a 4/4 full choke. There is even the Fudd choke ( from Bugs Bunny's Elmer Fudd ) that looks like a trumpet end and suggests it scatters shot wider than cy ( never tested one, but probably doesnt!!)

 

Ultimately, the only way of determining choke is to select the desired load and choke tube, and shoot the pattern plate. Count the pellets and refer to something like Eley's load infomation charts ( in the Eley Diaries every year).

 

Variations of +/- one theoretic choke size against the book measurements is common, as the individual cartridge type chosen is critical to the result.

 

BASC ballistic tests ( see full report on their site) also suggest that although choke measurements are linear increments, the pattern results are not - viz, the amount of narrowing of pattern between cy and 1/4 is much greater than from 1/4 to 1/2.

 

So, unless you have actually taken your gun out and patterned it with your different tubes and preferred cartridges, you only have an "idea" of what the various notches are doing.

Edited September 14, 2011 by clayman

[welshwarrior]

Clay mate great explanation wish I could have put it better in words thats what I tried to say.

[Old Bull]

cheers for the explanation guys i dont have to worry realy about chokes because all my guns are fixed chokes i was just wanted to know

 

my 410 is full/full and 12b is 1/4 and 1/2

[wymberley]

Just to add an historical footnote to clayman's superb piece.

It has been commented that when the figures appeared in Burrard that at the bottom or open end things were "tidied up" a bit and the 40% was the result. Rarely, if ever, on a true TC barrel will that percentage pattern be achieved using conventional cartridges. The effect on spread going from Imp Cyl to 1/4 - 50 to 55% is in line with the percentages relating to the tighter levels. However, nominal figures tell us that from TC to Imp Cyl is the biggest jump - 40 to 50%, but if the earlier remark is believed, then a further few percentage points can be added which proves the validity of welshwarrior's remark and then some.

[DSPUK]

What Clayman said in his very good reply is if you shoot a semi auto use 3/8 and if O/U use 3/8 and 1/2 - they will be good enough for anything.

 

Dave