choke size

[calvin humburg]

Can't find 10 guage choke sizes. Mine is around 785 full? ch

[Dave Suponski]

Calvin, I think the nominal bore size of a 10 gauge is .775 if memory serves.

[calvin humburg]

That would be .010 constriction that would make my choke? Just trying to figure out if its still full full. ch

[Mark Ouellette]

Hi Calvin,

Bores are different sizes so "785" doesn't really mean much.

Choke is the performance of pattern measured as percentage of shot within a given diameter circle at a stated distance. To obtain different chokes muzzles have constriction relative to the bore. If the muzzle of your 10 gauge is .785" what does the bore measure 3" to 4 " from the muzzle. If you could determine the constriction of the barrel(s) then we could tell you what choke performance you may expect.

As I'm sure you know that performance will be affected by a modern shot cup, hardness of shot, amount of shot, and even size of shot. The best method of determining choke is to shoot several rounds (5-10) at a 30" circle at 40 yards. I believe 70% is a full choke pattern.

I hope this helps,
Mark

[calvin humburg]

Thanks I'll try the 40 yd method. ch

[Francis Morin]

Hi Cal- David and Mark are right- but I like to pattern test my 12 bores with whatever loads each one is best suited for (LC Smith FW I stay with 1 oz. max, the Smith Std. frame 1 & 1/8 oz.- the No. 2 frame Parkers- with proof barrels- possibly a 1 & 1/4 oz. load in the left hand barrel, usually 1 & 1/8th in both-- But I just pace off what seems a fair bird killing distance, and shoot at a large mass of rusty scrap metal- old tanks, etc- that are found in a farm junk pile- and I mount and shoot as I do when bird shooting- NOT the rifle shot move that Mark suggested-- but the final criteria for me is- if the birds drop dead (assuming I do my part correctly) that's what counts-

Mark's method is best for determing POA- where you pattern impacts over your sight picture- and why do I prefer the mount then shoot- because when you pre-mount the shotgun, then fire for pattern, you usually have your cheek tighter on the stock comb, and are staring at the front sight bead- this is fine for a rifle with open iron sights (Win M-94 30-30 for example) but you will get a more accurate reading on your pattern if you shoot as if you are leading a screaming dove ripping downwind at 30 paces-IMO I also tend to prefer smaller shot sizes, even 7 & 1/2 shot for pheasants-

No need to discuss steel loads here- those are for my M12 pumpguns--:bigbye:

[Mark Ouellette]

Francis,

Point of Aim is at shot at 16 yards. At 40 yards one can certainly determine is POA is not center.

Personally I like to shoot at clay targets to determine if a gun is producing a tight or open pattern. I have an LC Smith Grade 3 12 ga with one barrel having a constriction of .008". That should be a bit more open than IC but it is not. With my 6000 PSI 7/8 oz loads it shoot a fair bit tighter as evidenced my breaking targets consistantly at teh trap range. This could be from a "hot core" or dense center of the pattern. This is a good barrel and load to actually shoot at paper to figure out how the barrel is actually patterning.

PS: Calvin, Some old Parker 10's had bores over .800". There was a recent thread on this oun the Hammer Gun section.

[Dave Suponski]

I agree with Mark. A .785 choke diameter would have to indicate a bore larger than that assuming there is some choke in there. Some of these old 10's had quite large bore's. You really need to check your bore diameter.

[Pete Lester]

Thanks to Scott K. I know my NH 10ga has .781 bores and .027 and .029 constriction in chokes that are about 4 inches long. It patterns full choke patterns with all loads, some are very "full". All shots with it have been fun. I learned that it is better to shoot skeet doubles on stations 1,2,6,7 in reverse order with a 10ga. There is plenty of choke to reach out and crush the going away bird on a second shot and I can take the incomer earlier, a little further away having a little wider pattern to work with.

[calvin humburg]

Don't have any thing to check bore size with. the parker letter says full full was what it came out with. thanks a bunch fellows!! ch

[Paul Harm]

If bore is .775 and you have .785, that means it's .010 bigger than bore size - or no choke. You'll need something to check bore size to know what your choke is. Paul