I am curious as to why bushing the firing pin hole would make a rifle shoot better. I am not doubting your report at all, but I would like to know if you have an opinion as to what caused the change in accuracy.
I am not familiar with the work that was done on the OP's rifle, so I cant speak to that. But I will say this, when I bush a firing pin I always grind the firing pin itself down and install the bushing long enough in length so that the pin is "guided"
thru it's entire travel in the bolt by the bushing. Once done, you go from having a floating firing pin that is unguided, except for the often ridiculous clearance that the factory gives {which affords really no guidance at all} to one that has about .002" clearance
the entire duration of it's fall in the bolt. You also go from having a well oversize firing pin hole in the bolt face to one that just fits the pin and is
now centered properly. Imagine having a firing pin that falls nearly dead zero straight {within .001" in any direction}, and now hits dead center. Now consider that you don't have primer cup metal flowing back into and sticking in the oversize bolt face hole {causing the bolt to "click" on opening}. Remember, all this is going on before the bullet leaves the muzzle.
I had posted photos of all this on here once upon a time, but I think photobucket killed it all. I will be happy to post them again if you would like further clarification, I know the way I explain this is hard to follow.
As far as actual affect on accuracy...from the time the sear breaks until the time the bullet clears the muzzle is critical as far as "unstable" or "inconsistent" movement in the rifle is concerned. The striker assembly is the largest moving part during this critical time. It is always best for accuracy if we can stabilize and add consistency to this movement.
My own personal rifle, the one I have the photos of, was barreled, bedded and stocked with a new trigger prior to the work. Groups were measured before and after only the bolt bushing and the groups showed improvement. It was not my "opinion" that the groups were smaller it is a fact. I will not say that it will work on all rifles and I am not saying that merely making the firing pin hole in the bolt face itself smaller will accomplish the same results or not...every rifle is different.
Edit: if you really want to see a loose hot mess, take a look inside the body of a 700 bolt with a borescope...it looks like a bunch of wild chimpanzee's in heat bored it out with a dull bit brace and finished to size with a chisel and big hammer!!!! That is what the round collar on the firing pin is trying to center on and be guided by when the striker assembly falls and we haven't even made it to the firing pin hole yet......
