Been lusting over a LW 243 BLR for a while. Is there a noticeable difference in the BLRs over the years?
The older design has the locking lugs arranged more-or-less helically around the outside/perimeter of the bolt head. The lugs lock directly to the steel receiver, IIRC.
The current-design bolt head looks VERY much like an AR-15's, only much larger. The lugs are radially arrayed, projecting outward from the front of the bolt head. The lugs on the current design lock into a steel extension threaded onto the barrel, again like an AR-15. The body shape of the bolt carrier is different now vs. the old ones, too.
The old steel receivers are thinner through the middle, and sort of 'flare' outward just a bit to meet the wood. The current aluminum receiver material is much thicker than the steel (I believe to retain the same strength, whilst being lighter), so they're slightly thicker through the middle and get just a bit narrower to meet the wood. This aspect isn't something one notices at a casual glance, but is very clear if/when looked for.
The old steel receivers have pins as the axles around which the lever, hammer, & gears rotate. The current aluminum receivers use 'tube' axles that I believe to be noticeably larger in diameter, with screw heads on each end (the one end is a screw that screws into the tube).
Aluminum can't be blued, obviously, so they anodized or painted or covered in bear droppings or something.
The color-matching between the aluminum receiver and blued-steel barrel is very good; better than the color-matching on many all-steel-but-differently-heat-treated (and containing MIM parts) bolt guns. I can't comment on the stainless ones as I've not handled one.
I love the pistol-grip models, and would really like a take-down.