I'm going to take a bit of a hard line on the definition of "restoration" and "original".

As I see it, "restoration" as pertains to firearms collectors is closer to the furniture collector's definition than the car collector's definition. Furniture collectors usually seem take a dim view of refinishing a piece or replacing major damage/alterations -it usually hurts value. Car collectors, on the other hand, want the car to look and drive like it did when it was new - a frame-off restoration (where everything is refurbished or replaced to "like-new") is the desired condition.

For me, "original" or "correct" as it pertains to firearms is, simply put, the state that a firearm was in while in service or military ownership. That could mean either a) the way it left the factory, b) the state it was in when issued and used, or c) the state it was in when surplussed off to an exporter. All three conditions represent the weapon's use in military service. A is usually much rarer and more valuable than B or C, but all three could be called original or correct since they represent the weapon as a military firearm. Collectors may also take an even harder line and define "correct" solely as a weapon that has never undergone arsenal repair or refurbishment.

A "restoration" would be a rifle that has been returned to "original" or "correct" condition after having been irreversibly altered. It would be largely functionally and visually identical to an original, but not itself original - the finish and some parts may be modern facsimiles of original finishes and parts.

For me, doing a restoration on a "bubba" modified rifle is fine and even laudable - as long as the weapon is always properly represented as non-original. *It will still be worth less* than an original example, but it is at least correct in appearance and function, making for a good shooter, project or display piece.

Another scenario where restoration is appropriate is when a weapon is legally restricted or so rare that replacement parts may simply not exist and must be fabricated, or are not legally available. In that case, the restoration itself (if properly done) may become the best possible representation of an original piece. This is a case where the restoration may actually *increase* the value - one common example would be imported machine gun "parts sets". When assembled in to working guns with modern semi-auto receivers they are technically restorations, but since original receivers are unobtainable, the restoration is nearly as close to the original as you can ever get (barring the few transferable guns out there).

Sometimes, doing a restoration may be a bad idea. One example of this situation would be a Mosin-Nagant modified by Bannerman's. These might look like they are sporters, and they are - BUT Bannerman's sporters are historically significant and collectible in their own right, and should be classed as "originals". Returning these rifles to as-issued Russian condition would be a mistake - many (most/all?) of these rifles were never issued in Russia anyway.

So, in short, the answer to the original poster's question is "it depends".

I don't like to modify my rifles in any way - I even keep the flaky shellac finish as-is on my Mosins. I put a no gunsmithing scope mount on my Yugo M48, and swapped out the original battle sight on my No. 4 Mk 1 with an original Jungle Carbine micrometer sight. That's the extent of the changes I would make. Both are totally reversible, and in both cases the changes were made at the beginning of my collecting career - nowdays I might not do even those modifications. Other than those, the only changes I will make would be the replacement of broken or missing parts with correct original parts.

For me, an original condition rifle is the only kind I'm interested in collecting. I might be willing to buy a "bubba" sporter as a project gun, in order to restore it for use as a shooter, but I would only buy it at a big discount. "Bubba" rifles are only good for parts or project guns, so unless it's an exceptionally rare type of gun, they aren't worth much to me.

The biggest issue with "restorations" are when they are represented as originals by unscrupulous people. At this point they are no longer restorations but fakes, and they are the collector's bane.

I agree with zeebill in the sense that a restoration always risks being represented as genuine by an ignorant or unscrupulous seller. YOU may be honest about it but the next guy may not. It is one of the risks of collecting. Bubba rifles may be more or less easy to spot, but a restoration is designed to be hard to spot (whether your intentions were good or bad). We can't make the bubbas and fakers go away though, so the best defence is always going to be "know what you're looking at". I never take a seller at his word. I only listen to what the gun tells me under examination.

A Mitchell's M48A was my first milsurp, and I learned a lot from that purchase. Despite having overpaid, I did at least get a genuine milsurp rifle in (arguably) its original condition, which is more that one could say for a $550 reblued, sanded Mosin. I'm happy with it. But if I could do it all over again I would have passed on Mitchell's, not because of the rifle itself or even necessarily the price, but because they misrepresent what they are selling and I consider it very sloppy at best and dishonest at worst.

That M48A was the only milsurp I didn't really research before buying, and it will remain the last rifle I buy without researching.