The physics are pretty simple. Bullpup designs lower the axis of the bore in relation to the stock, usually so the axis of the bore extends through the butt of the firearm. In more "conventional" designs, the axis of the bore is considerably above the butt. By changing the geometry, bullpup designs have the recoil forces, which are directed backward along the axis of the bore, pushing the shooter straight back. Conventional designs, with the axis above the butt, create a lever arm for angular momentum. Thus, some of the recoil is translated into muzzle flip.
Muzzle flip is perceived as greater recoil, in part because it throws the sights off of target, and shoves the stock into the cheek ( or face if you do not have a good cheek weld).
Thx! I appreciate the clear concise explanation.
While I understood the concept of “muzzle flip” as it pertains to handguns/target reacquisition; your final paragraph helped clarify how/why “muzzle flip” translates to decreased “perceived recoil” in a bullpup design.
I presume the only downside to bullpup design is placing the chamber closer to the shooters face (gasses from spent cartridges/increased danger to the shooter in the even of a critical failure due to overpressure) and a shorter sight radius. Any other pluses or minuses in your opinion?
Regards,
-Geoff