It all depends upon the barrel thickness you begin with. Whatever metal you cut out to lengthen an existing chamber will reduce the remaining chamber thickness. Some barrels though are thick enough to extend the chamber and still be well within safety requirements.
For example, in an earlier thread I mentioned an ithaca/lefever single shot 20ga I have that had the chamber extended from 2 3/4" to 3". Most American single shots are built pretty stout. The gun I have is particularly thick from the breach to the end of the action, well over three inches long. I had mine measured as a precaution and the extended chamber walls extending well into the forcing cone are at the thinnest .130" thick. I will open the turkey season in the morning with it.
SXS guns are built for weight distribution and handling comfort, so even American doubles are more likely to have a barrel thickness problem in the chamber area than single shots. But, some are certainly built strong enough to be OK with a chamber extension. I'd venture that most "duck" guns will stand a chamber extension whereas many "bird" guns simply won't. Measure twice ream once...Geo
Last edited by Geo. Newbern; 03/22/19 07:45 PM.
