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Briley makes choke tubes for Yildiz guns but only in 12 gauge Trulock is making them now in standard and extended versions. http://www.trulockchokes.com
Only with cylinder and improved cylinder choke tubes.
Extended - extends beyond the barrel Flush - does not extend beyond the barrel
What gauge and grade is it?
Browning Invector.
Charles Daly 20 gauge shotguns typically use Beretta/Benelli mobil chokes, which means that any choke tubes designed for these systems should be compatible. It's always best to verify the specific model of your shotgun, as there may be variations. Additionally, ensure that the choke tubes you purchase are rated for use with 20 gauge ammunition. Always consult the owner's manual or the manufacturer for the most accurate information.
A 12 gauge shotgun with changeable choke tubes that fires 3.5" shells.
Browning made choke tubes.
mossburge chokes r the same as stoegers
Try gun shops, gun shows, want ads, e-gunparts.com
Modified describes a choke. Invector is a system of choke tubes.
You don't give us the model, so it is hard to answer the question. Assuming the gun does not have an obvious adjustable choke, the choke is probably not easily adjustable. A gunsmith can open the choke (from Full to Modified for example) or can install internal interchangeable choke tubes (costs around $125).