Found some info for you!!
This site seems to have some good info:
http://www.pmulcahy.com/bolt-action_sporting_rifles/us_ba_spr_l-m.htmIt was really slow loading for me so here is what they had to say about the 810:
Notes: Though based partially on the Model 800, the Model 810, is not, as some people think, simply a long-action version of the Model 800, as there are many differences other than the length of the action. The Model 810 has several other internal and external differences, including the bolt, which has a pair of four lugs instead of three, and the trigger unit, which has a conventional firing pin instead of being striker-fired, and also allows for adjustments for length and weight of pull. The trigger unit is also a self-contained unit instead of being just another collection of parts of the rifle. The Model 810 has a "blind box" magazine; the small magazine is fits entirely within the receiver and is concealed under a floorplate. (After 1973, versions with internal magazines were also introduced, and the popularity of the box-magazine versions markedly decreased.) The walnut half-stock is of the Monte Carlo-type, but has a low comb instead of the Model 800’s higher one. The buttplate and the cap of the pistol grip had decorative white plastic spacers. Production lasted from 1972-78.
The base version was the Model 810A, chambered for .30-06 Springfield, with a 22-inch barrel and a folding leaf rear sight. The internal magazine counterpart was the Model 810AH. The Models 810B and BH were chambered for 7mm Remington Magnum and Models 810C and CH were chambered for .270 Winchester. Models 810D and DH were chambered for .338 Winchester Magnum; though otherwise the same as the other versions except for the chambering, these two models used a 24-inch barrel and had smaller magazine capacities. The internal magazine-fed versions have slight weight differences, but shoot identically to the box magazine-fed versions for game purposes.
