They are strong enough that I built a double rifle in calibre .303 British on a 20 gauge Laurona a few years ago. It is still tight and on the face after 1000's of rounds through it. The Laurona boxlocks have double Purdey-style underbites, a Greener-style crossbolt, a breech re-inforce, disc-set stikers, and quite often they have side clips as well. Although, as noted above, they are an entry-level gun, both they and the Zabalas are a lot of gun for the money.