spandit Posted December 2, 2013 Report Share Posted December 2, 2013 I know measuring the muzzle with calipers isn't the most accurate way of doing things, but my 12 bore barrels seem to be 1/4 and Full choke - does that sound normal for an English SbS? The forward trigger fires the right hand barrel which is the 1/4 choke one Quote Link to comment Share on other sites More sharing options...
Dave-G Posted December 2, 2013 Report Share Posted December 2, 2013 I can't hear anything. Quote Link to comment Share on other sites More sharing options...
sishyplops Posted December 2, 2013 Report Share Posted December 2, 2013 Get your local dealer to check with a bore stick, I measured my SxS with a brass gauge and it came to 1/4 and 3/4, gunsmith measured today at just over 3/8 and tight full, yes the right barrel fires first (front trigger) Quote Link to comment Share on other sites More sharing options...
JohnfromUK Posted December 2, 2013 Report Share Posted December 2, 2013 Could well be right. It is usual (though there are exceptions) that the right barrel has less choke. Remember that choke 'by measurement' is only an approximation since it depends on the main bore diameter (most measurement based choke approximations assume the main bore is .719") and other factors (forcing cone shape, choke profile etc.) and guns will also pattern differently with different brands of cartridge. Quote Link to comment Share on other sites More sharing options...
browning123 Posted December 2, 2013 Report Share Posted December 2, 2013 Could be normal for an English gun. Quote Link to comment Share on other sites More sharing options...
poontang Posted December 2, 2013 Report Share Posted December 2, 2013 Remember that choke 'by measurement' is only an approximation since it depends on the main bore diameter (most measurement based choke approximations assume the main bore is .719") and other factors (forcing cone shape, choke profile etc.) and guns will also pattern differently with different brands of cartridge. Is the correct answer. Quote Link to comment Share on other sites More sharing options...
spandit Posted December 2, 2013 Author Report Share Posted December 2, 2013 I understood it was .729", which is stamped on my barrels. Anyway. At least I now know which barrel has less choke - just need to learn which one to fire first! Quote Link to comment Share on other sites More sharing options...
JohnfromUK Posted December 2, 2013 Report Share Posted December 2, 2013 I understood it was .729", which is stamped on my barrels. You are absolutely right. 12 bore is .729. My mistake, but a lot of older English guns are proved at .719, known as a 13/1. My mistake and you are right at .729 Quote Link to comment Share on other sites More sharing options...
spandit Posted December 2, 2013 Author Report Share Posted December 2, 2013 You are absolutely right. 12 bore is .729. My mistake, but a lot of older English guns are proved at .719, known as a 13/1. My mistake and you are right at .729 No harm done, mine doesn't have the original barrels, don't know how old they are (reckon the rest of it is 100 years old or so) Quote Link to comment Share on other sites More sharing options...
spandit Posted December 3, 2013 Author Report Share Posted December 3, 2013 Get your local dealer to check with a bore stick, I measured my SxS with a brass gauge and it came to 1/4 and 3/4, gunsmith measured today at just over 3/8 and tight full, yes the right barrel fires first (front trigger) I was right, 1/4 and Full... Quote Link to comment Share on other sites More sharing options...
Guest cookoff013 Posted December 3, 2013 Report Share Posted December 3, 2013 sounds plausable. Quote Link to comment Share on other sites More sharing options...
deershooter Posted December 3, 2013 Report Share Posted December 3, 2013 The correct way to measure choke is to measure the barrel and then measure the choke 40 Thou being full choke ,no brass gauge or caliper will do this correctly don't take what it says on the barrel lots of old UK guns have been honed out to remove pitting . Deershooter Quote Link to comment Share on other sites More sharing options...
Canis Posted December 3, 2013 Report Share Posted December 3, 2013 My understanding was that a bore of .724" to .729" was considered 12 bore (18.4-18.7mm.) constrictions of choke taken by measuring constrictionsat muzzle against actual barrel bore. from actual, 0.005-0.008" constrictionusually taken as skeet, 0.010" as 1/4, 0.020 as 1/2 , 0.030" as 3/4 and 0.040" as full not sure exactly how the imperial bore constrictions metricate though! as said before its actual measured not as stamped on the barrel. Don't assume on a double gun that both barrels will be exactly the same for bore measurement either Quote Link to comment Share on other sites More sharing options...
HDAV Posted December 3, 2013 Report Share Posted December 3, 2013 Also remember the constriction is only part of the deal its the pattern that the constriction produces that matters...... Shot load, size and wad all play a part, Quote Link to comment Share on other sites More sharing options...
Hector Vector Posted December 3, 2013 Report Share Posted December 3, 2013 A "12 bore" ranges from .710"(13 in old money) to .740(12/1) with .719(13/1) and .729 (12) in between. Old English guns don't use Skeet; 0.005" is taken as I/C with 10, 20, 30 and 40 thou as 1/4, 1/2, 3/4 and full respectively. The smallest measured increment of choke is usually 1/8 (0.005"). Choke is the relative difference between the muzzle constriction and the bore measured 9" up from the muzzle. To accurately measure choke you need a proper (Chubbs type)bore gauge. I've never had an English gun with choke sizes marked on the barrel flats. Even if the flats have the degree of choke marked on them it may no longer be accurate if any barrel work has been carried out. Quote Link to comment Share on other sites More sharing options...
Dekers Posted December 3, 2013 Report Share Posted December 3, 2013 The correct way to measure choke is to measure the barrel and then measure the choke 40 Thou being full choke ,no brass gauge or caliper will do this correctly don't take what it says on the barrel lots of old UK guns have been honed out to remove pitting . Deershooter ......or simply the owner wanted something different. Quote Link to comment Share on other sites More sharing options...
Grandalf Posted December 3, 2013 Report Share Posted December 3, 2013 Lots of old guns had this sort of choking. Open first and tight second barrels. Theory was that you could always have it opened out as an after sales service. It couldn't be added in the days before multichokes. Quote Link to comment Share on other sites More sharing options...
HDAV Posted December 3, 2013 Report Share Posted December 3, 2013 It couldn't be added in the days before multichokes. Actually it could...... Quote Link to comment Share on other sites More sharing options...
BobbyGee Posted December 3, 2013 Report Share Posted December 3, 2013 Lots of "Old English" guns have chokes like yours, 1/4 in the first barrel and full in the second because lots of shooting was carried out "walked up". You took the first shot when the bird was fairly close and if you missed it had flown futher away so needed a tighter pattern to put it down. Could be a fair advantage if you shoot decoyed pigeon, tight barrel first (when the bird is coming towards you) and in the unlikely event of you missing he gets the second barrel when he is a lot closer! Quote Link to comment Share on other sites More sharing options...
Hector Vector Posted December 3, 2013 Report Share Posted December 3, 2013 ...by opening out the bore and leaving the choke as is. Choke is a relative measurement. I can't imagine anyone wanting to do it though! Quote Link to comment Share on other sites More sharing options...
spandit Posted December 3, 2013 Author Report Share Posted December 3, 2013 Thanks, chaps, I've bought some cartridges today so have plenty to play with Quote Link to comment Share on other sites More sharing options...
HDAV Posted December 3, 2013 Report Share Posted December 3, 2013 ...by opening out the bore and leaving the choke as is. Choke is a relative measurement. I can't imagine anyone wanting to do it though!Correct sir, I don't fancy the idea but it has been done.... Quote Link to comment Share on other sites More sharing options...
Grandalf Posted December 4, 2013 Report Share Posted December 4, 2013 Actually it could...... Expensively! Quote Link to comment Share on other sites More sharing options...
HDAV Posted December 4, 2013 Report Share Posted December 4, 2013 Expensively! Yep, Possible and practical aren't the same thing... Although to ream out a few though isn't a big deal many older guns have pitting lapped out its just how many thou you go.... Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.