And I still pretty much have to disagree, V2. For starters, an uncut AR15 style bolt colt carrier will
work in conjunction with pinned in Colt sear block. Allow me to save a couple thousand words with the following images:
Here is my blue label Match HBAR R6601 built in 1990 with the early 3 pin style block:
Here is the same lower receiver with an AR15 style bolt carrier from my green label Gov't Model R6550k shown where it would normally rest relative to the lower receiver:
As you see, the uncut lower portion of the bolt carrier comes nowhere near into contact with the sear block portrusion. My experience represents what has been reported by other members who have tried this as well. So again, I have to ask if you have actually attempted this or are merely theorizing about what would happen. If you did try it, perhaps you somehow got an M16 style bolt carrier, which is what the sear block portrusion is designed prevent from being installed.
As for altering a a weapon and therefore it's value, that can cut both ways. As you can see in the images in my second reply, I did a very clean job of removing the block. No hack marks, gouges, scratches, anything other than just a little bare metal on the inside of the pin where I cut through it with a fiber wheel. If you think that is "butchered", I don't know what to say as most people consider it an excellent job. I've also had the lower receiver drilled to accept the spring and detent for a GI style forward pivot pin. Did that deviation (one most people would appreciate, I might add) from the factory configuration lower it's value, too? Perhaps this lower receiver would now be worth less to that rare collector looking for a pristine example of an R6830. Hell, guns lose value just by shooting them. Do you let that stop you from firing your guns? I sure don't. This lower receiver would also be worth more to someone looking for one in which to use a DIAS or LL, too. Like I said, it could go either way, or more likely nowhere at all. My R6601 will also one day either lose it's needlessly heavy barrel in favor of a Colt USGI M16A2/AR15A2 style barrel or have it's heavy barrel turned down to A2 specs and a bayonet lug added. I doubt resle value will harmed, in fact it will probably be enhanced, and I'll have a rifle more in line with what I want to boot. And let's be honest here, we're talking about blue label Colts, not exactly a rare commodity. I would discourage the alteration of the more rare and valuable Colts, too. At any rate, I'm very happy with the modifications, and that's all that matters to me. My grandkids can worry about resale value when I'm gone.
Regarding the .22 conversion kits, I have to renew my question as to whether or not you have any experience with them. What you claim occurs has not been borne out during my experiences. If the .22 bullets were being shaved by the 1/7 twist, there would be excessive leading of the barrel. It would not simply get "blown from the barrel". Accuracy would be extremely dismal. Speaking from experience and not what some vague "operator" may or may not have reported, I can say that none of that is the case. I do not have excessive leading after shooting .22LR ammuniton through my 1/7 barrels, accuracy is good enough to repeatedly hit a soda can size target at 100 yards, and there is enough remaining energy left to make that can dance as any of my regular .22LR rifles would. I would respectfully suggest posting these claims in the Rimfire Forum to see what they have to say about it. Perhaps my experience is an anomaly. But I doubt it.