Have to be careful with bullet shape and seating depth on those issues sometimes. I really wanted to shoot heavy hardcast big meplat in my 458 backup gun. Will not feed them. But it flawlessly feeds 350 barnes as fast as I can cycle the bolt.
Not at all uncommon IME that the newer FP solids many of us now favor, either hang up or fail to feed at all. Usually this is not a problem related to the CRF mechanism itself but rather the alignment of the bullet tip relative to the feed ramp. The most common cause I’ve found is a combination of the width of the feed ramp, the angle of the ramp at the corner, and/or the presentation of the cartridge by the bolt face before the extractor captures it, as the cartridge begins to exit the magazine box early in the feed cycle. That type of jam can be stubborn to clear rapidly, usually at the most inconvenient time.
Depending on the cause, especially if the action left the factory configured for a different cartridge than its current state, polishing the feed ramp, correcting the feed ramp width and/or angle will allow FP solids to feed without trouble. Sometimes modifying or replacing the follower and/or magazine spring may be necessary. If the problem of alignment is minor and follower construction allows it, modifying the shape of the follower surface might work.
Less frequently, but not unheard of, is the timing of the feeding cycle, due to the shape and/or width of the feed rails. This is especially sensitive as it’s very easy to ‘improve’ the feed rail configuration into dysfunction. Easy to do but difficult to correct except by an expert GS who understands CRF cycling very well. Attention to the shape, tension and extractor-to-rim fit are also important.
Many of the older CRF actions were not designed with blunt FP solids in mind and so some tweaking is necessary. I suspect a lot of the jams blamed on CRF or on the action are the result of operator error, inexperienced with rapid cycling of the bolt - especially H&H length ones - under stress. Practice, both dry fire and many practice loads, with a portion of full power loads, is the solution to the operator problem.
Although the double barrel DGRs are indeed faster for the 2nd shot, it takes a skilled and practiced operator, as Craig Boddington has pointed out, to find the 2nd trigger and extract that speed. Most of us are much more experienced with a bolt action rifle and investing the time and attention to improving cycling speed with a well tuned DGR pays off in the end.
BTW, our ingrained tendency to depend on 1-shot, DRT North American and PG experience serves us poorly in DG hunting. Shooting accurately, rapidly, and often rather than admiring our handiwork after the 1st shot is a good rule with DG.
In my case, I started out hunting elephants with a double DGR, enjoyed it and found it works. I realized however, that I was still more comfortable with a bolt DGR and after figuring out the quirks of the actions, fixing the issues mentioned and spending a lot of dry fire, practice load and full power load time on the range, have switched to bolts. Still a bit slower with the 2nd shot than the double, but fast enough for follow ups and, with either 3-down or 4-down magazine boxes beyond the chambered round, better suited to deal with that other elephant that decides to come out of the corner or move forward to protect its fallen herd mate. Such a bolt action DGR adds some subconscious peace of mind that the conclusion of the encounter will favor the shooter.
Those are just my conclusions based on a limited sample. YMMV.