Ok, so what you're saying is that you're not talking about the bullet that the OP is talking about, because he asked about the HORNADY GREAT PLAINS bullet.

I assumed that the Lyman mould was a copy of the Hornady design. Since it's not, and more importantly, since you knew it's not, why did you post regarding the accuracy of a different bullet?

Mike

The guy called "liquidorange" posted that he could get a mould for the "plains- bullet"
My reply was
"The lyman great plains bullet in not a good bullet. I make a lot of bullets for ML's and the Lyman is the bottom of the list for accuracy. Ron"
Since the Lyman is the only mould that is named "great Plains" I responded to the quality of the bullets made from that mould. Hornady great plains bullets are swagged, and there is no mould for them.

YOU then posted that "Maybe you weren't molding them right."
My reply was that in fact the Hornady is a very good bullet, The lyman was crap, and since you called in to question my skills making bullets that yes I do make bullets that are accurate, and maybe someone that sees this post might think twice about getting a Lyman mould and think a little more about the 500 S&W mould since it does shoot good. I also posted info about my rifle and twist so if someone had a similar twist they would know the 500S&W bullet does indeed work.

In your reply you quoted me. You said " I suppose if you're using a RB twist, the long bullet would probably not stabilize well and show accuracy problems, but in a 1:28" or faster twist, they are great. They hit hard too."
My post cleared that up as well, I used the right twist.
Ron

just pulled out my mould and it is indeed a lyman 395 grain plains bullet . i remember casting a bunch of these 10 years ago. dont remember how they shot in my 1-48 twist new englander. maybe if i get a lead supply i will have to see what they can do. im guessing the 370 grain maxi balls i settled on back then probably shot better.

In all fairness, the rifling of every brand of barrel is different. There's square bottom, round bottom, deep, shallow, different numbers of grooves, gain twist yada yada and that's not considering the variations in bore diameters, twist rates and loading different powders.
Some bullets do shoot better from more barrels than others, but that's not to say that any bullet, or even the Lyman Plains Bullet just won't shoot under any circumstances.
Maybe it has a poor design or lacks proper sizing. However .50 caliber bullets can also be run through a sizing die and shot out of a .54 bore using a sabot.
It's plausible to think that for every bullet there's a bore that will shoot it fairly well, even if that bore hasn't been manufactured yet.
After all, fast twist barrels were developed long before conical bullets were even invented. So I'm sure that many folks back then didn't think that fast twist barrels could ever be made to shoot any good either.

Well I even tried paper patching the Lyman Great plains bullet. It didn't help it one bit. Maybe there is a rifle out there that like them but neither one of mine do. Ron

I was sad to see Hornady quit making the 525gr 58cal Great Plains conical. That was a great conical in my 58cal. Sure would have done some damage. Might as well melt down what I have left since I wont be able to get them anymore.