Keith RW Posted November 24, 2022 Report Share Posted November 24, 2022 Evening All looking to identify the chokes on this 12g Belgian Guild Boxlock which if I am correct and from its makers marks is a 1938 SBS Am I correct in assuming that both the bores started out as 18.4mm with the "18.5mm CHOKE" marking indicating a 0.5mm- 1/2 choke on that particular barrel and the other remaining as Cylinder choke Quote Link to comment Share on other sites More sharing options...
TOPGUN749 Posted November 24, 2022 Report Share Posted November 24, 2022 (edited) My understanding is the bore is measured at 18.5mm( .728”) and the choke is 18.4mm (.724”) so 4 thou,or improved cylinder.The right barrel could be 18.4mm and no choke.You can check with a cleaning rod and patch,there should be a slight tightening felt on the left barrel at the choke,and none in the right! Edited November 24, 2022 by TOPGUN749 Quote Link to comment Share on other sites More sharing options...
Keith RW Posted November 24, 2022 Author Report Share Posted November 24, 2022 13 minutes ago, TOPGUN749 said: My understanding is the bore is measured at 18.5mm( .728”) and the choke is 18.4mm (.724”) so 4 thou,or improved cylinder.The right barrel could be 18.4mm and no choke.You can check with a cleaning rod and patch,there should be a slight tightening felt on the left barrel at the choke,and none in the right! Cheers Topgun, got the numbers completely wrong with earlier post, no idea why my brain figured there was a 0.5 mm difference between 18.4mm and 18.5mm and not .1mm Quote Link to comment Share on other sites More sharing options...
enfieldspares Posted November 25, 2022 Report Share Posted November 25, 2022 11 hours ago, Keith RW said: Cheers Topgun, got the numbers completely wrong with earlier post, no idea why my brain figured there was a 0.5 mm difference between 18.4mm and 18.5mm and not .1mm The Diane Abbott "School of Gunsmithing" - Chapter 1 - Choke Measuring perhaps? Quote Link to comment Share on other sites More sharing options...
Keith RW Posted November 25, 2022 Author Report Share Posted November 25, 2022 2 minutes ago, enfieldspares said: The Diane Abbott "School of Gunsmithing" - Chapter 1 - Choke Measuring perhaps? That and a combination of busy day brain fade and topped off with a cider or two Quote Link to comment Share on other sites More sharing options...
Gunman Posted November 25, 2022 Report Share Posted November 25, 2022 .Who knows what hast happened to the gun since new . So why not just get it measured .Takes 3 minutes and any gunshop /RFD should be able to do it for you . If they cant then its a shop to avoid . Quote Link to comment Share on other sites More sharing options...
Stonepark Posted November 25, 2022 Report Share Posted November 25, 2022 13 hours ago, Keith RW said: Evening All looking to identify the chokes on this 12g Belgian Guild Boxlock which if I am correct and from its makers marks is a 1938 SBS Am I correct in assuming that both the bores started out as 18.4mm with the "18.5mm CHOKE" marking indicating a 0.5mm- 1/2 choke on that particular barrel and the other remaining as Cylinder choke When numbers are unclear to what they relate, I would take everything with a large pinch of salt, though the left barrel is often tighter traditionally than the right, however in some guns this is reversed, so is not an absolute and reverse choked barrels are not unheard of. Th only reliable and best way to establish choke is to pattern each barrel of the gun with a 5% antimony fibre cartridge at 40 yards and count pellets in a 30 inch circle. The number of strikes divided by original number of pellets in a cartridge will give you the percentage choke. For consistency and to keep costs down, I use a clay cartridge for patterning. Quote Link to comment Share on other sites More sharing options...
wymberley Posted November 25, 2022 Report Share Posted November 25, 2022 If you think that you'll ever need to do this again then a long reach telescopic gauge and some calipers or micrometer will give you the nominal boring to a working standard. Failing that, as already detailed. For practical purposes with the cartridges that you're considering using a properly conducted pattern test will tell you exactly what you need to know. The two results although both correct may well differ. Quote Link to comment Share on other sites More sharing options...
Keith RW Posted November 25, 2022 Author Report Share Posted November 25, 2022 15 minutes ago, wymberley said: If you think that you'll ever need to do this again then a long reach telescopic gauge and some calipers or micrometer will give you the nominal boring to a working standard. Failing that, as already detailed. For practical purposes with the cartridges that you're considering using a properly conducted pattern test will tell you exactly what you need to know. The two results although both correct may well differ. A long reach telescopic gauge would be a nice edition to the toolkit but as mentioned patterning is the practical way to go and all part of the fun with regards to keeping the old guns up and running. I only plan on using this with light loads and obviously at shorter ranges with having little or no choke, Quote Link to comment Share on other sites More sharing options...
wymberley Posted November 25, 2022 Report Share Posted November 25, 2022 19 minutes ago, Keith RW said: A long reach telescopic gauge would be a nice edition to the toolkit but as mentioned patterning is the practical way to go and all part of the fun with regards to keeping the old guns up and running. I only plan on using this with light loads and obviously at shorter ranges with having little or no choke, Please sing out the result as all that springs to mind with those marks is Starshot. Quote Link to comment Share on other sites More sharing options...
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