I like carbines!
From my documented experience, loss of velocity can be broken into a couple categories.
One category is that of taking a given rifle and cutting the barrel off. There is a measurable loss that will only effect the paper ballistics, unless you let it effect how you feel about it. Whatever you shoot will never know the difference. Also, the pressure you are running at will increase or decrease the amount of loss per inch. IE the higher the pressure the more the potential loss per inch. Yes, I know, there have been countless studies done over the year that show the loss in a particular barrel as it was cut off one inch at a time. I've studied several of them. I've also shot my own.
Another category pits a factory rifle with an unaltered barrel to against a custom rifle with a custom chamber and shortened barrel. This situation we have at our house. Our Remington700 30-06 with factory 22" barrel runs less than 10fps different than our Interarms Mark X with a custom 20" barrel and a tightly cut chamber. This showed up on the Chronograph with our hand loads we were testing, so we ran some Winchester factory loads as a proof test, and the insignificant defence remained consistent.
You've had your rifle re chambered. It is in fact somewhat of a custom chamber. You may find less velocity than what you had by some measurable amount, but you may also find you have the same or nearly the same velocity as a 22" barrel with the standard factory chamber. WHY? Because standard factory chambers tend to be loose, to varying degrees. Tight chambers run higher velocities with the same load than do loose chambers.
Like a carbine? Cut the barrel and move on to enjoying the easier handling that you enjoy.
Regards,
Sweetwater
