Monolithic bullets typically have a couple features that require special considerations as compared to conventional lead core jacketed bullets. First, they are typically made from some type of gilding metal, which is not as dense as lead. For that reason, they tend to be much longer for a given weight class and may require significantly faster barrel twist rates in order to properly stabilize them. Second, the relatively long ogives may also necessitate rigorous seating depth testing in order to determine exactly where they need to be seated in order to group optimally. Typically, these issues mean you may need a fairly fast twist barrel for the bullet weight class and a long throat to seat them optimally. Depending on the rifle setup, it may be necessary to specifically optimize barrel twist and throating to obtain good performance from the monolithics because not all rifles, even competition rifles, will set up optimally for these bullets.
I happened to have a 9-twist .308 barrel with a low round count that was originally set up specifically for a monolithic bullet that was not in use because the manufacturer stopped making that particular bullet a while ago. So I replaced the barrel with a more suitable barrel/chamber for the conventional bullets I have been using. I recently spun that barrel back on and tested a monolithic bullet and the precision in my hands was simply not there. The velocity data were outstanding, but the groups were literally 2-3 MOA at 100 yd. In fact, it was somewhat like shooting a precision shotgun. I have reason to believe the bullets were actually wobbling or "balloting" in the bore due to a combination of the relatively short bearing surface and the seating depths I was using. In fairness, I suspect I could have markedly improved the precision with more rigorous and thorough seating depth testing; I'd guess this particular bullet probably needed to be seated into the lands to facilitate straighter entry into the bore upon ignition. Unfortunately, if you have to test a excessively large number of rounds during load development, the cost of monolithic bullets can be sometimes pretty steep, even by my standards. I needed to put the other barrel back on that rifle for competition purposes, so I have not yet finished the seating depth testing, but I do intend to get back to it at some point and I have just enough bullets remaining for that purpose.
My overall take is that if you can get them to group with good precision, you will essentially be getting the BC of the next heavier (longer) class of conventional lead core bullet, but with the higher velocity achievable in the next lighter class of bullets. These characteristics would certainly be highly desirable if you can get reproducible precision. If not, the extra performance isn't worth much. As mentioned above, the other downside is if you decide to have a fast twist barrel cut specifically to shoot a particular monolithic, and the results aren't what you hoped, you've just spent a fair bit of time and effort for little return. My suggestion would be to get the best loading info you can from the manufacturer and/or find someone that has actually gotten good precision with your monolithic of choice and try to reproduce what they have done exactly. Unfortunately, I can't help you out much there as I haven't yet been successful with them.
