Some personal observations based on experience and guns examined & seen for sale at shows:
I don't think you have concern for choke damage w/full choke constrictions IF you stick to modern loads, even w/steel shot [much tougher plastic & better designs in the newer steel shot wads] & shot sizes of size 4 or smaller. Having said that, I would NEVER shoot anything but lead shot or bismuth in an FN or any of the older German guns [or any high grade gun for that matter] for the simple reason that I have seen and examined several that had their Full chokes bulged, presumably from the use of hard steel shot. It may have been too large shot as well, but I had no way of determining that as these are mostly guns that were for sale at shows I am speaking of. I have also seen guns w/heavily scored bbls. in the form of straight line striations [think crude straight rifling] from early steel shot loads where the pellets penetrated the wads' petals or wall. Again, I have no way of knowing the exact loads used to do that damage; it could have even been some enterprising sort who was using BB gun BB's w/regular lead shot wads! There was sufficient talk & discussion when steel first came into use to know wad petal penetration occured w/some early factory ammunition & recovery of some of those wads confirmed it. Too, some some pellets were overly hard & some early wads left exposed shot above the petals .. so I would avoid using any early or old steel ammuntion in any gun I was remotely concerned about, period. An 870 Express Magnum, Mossburg 500 or any of the inexpensive modern purpose built waterfowl guns can eat that stuff w/impunity. FWIW, I have an older 870 Wingmaster w/fixed Full choke constriction of .041 that has digested around ten flats [50 boxes of 25 cartridges] of 2&3/4" Steel #4 loads made by Remington, Federal & Winchester w/o any sign of damage whatsoever. I'm not suggesting you do that with your valued doubles, but a Browning BSS [Miroku mfg.] choked F&F can handle factory steel loads up to size 4 w/no fear & so can some other more modern doubles. I have shot 1&1/4oz. of Remington & Federal steel 4's through a 3" 12ga. Beretta 686 w/factory flush fitting 'Mod' screw-in chokes repeatedly to no ill effect & they remain easy to remove for cleaning or switching.
As to the shooting of lead shot target ammo w/plastic wads through full choke constrictions, none of us will have the opportunity to be around long enough to measure any wear or see any damage from it. Think ATA trap shooting .. Full chokes for the most part & endless shooting. They do OTHER stuff to damage their guns;-)
In summary, plastic used in wads is 'softer' than lead, don't sweat it's use.
Perhaps something here to help allay your concerns.
kind regards, tw
