I think we have to look at the question asked in the start of the thread. "Can Remington 700 repeater beat 1/2 MOA?" The answer is YES! Will
all REM 700 's do it? Absolutely not.
Now the question seems to be morphing into can anyone with a REM 700 shoot .5 or better or will a factory gun beat a highly customized rigg? Again, absolutely not! Wind, loads and a million other variables will be working against the shooter and forcing him/her to use their skill/knowledge to get the most out of their guns be it at a bench rest shoot, long range shoot or plinking in a field with buddies. Then you have the custom guns where the build is designed to remove the small imperfections that cause a gun to be mechanically less of a shooter.
The reality is, some factory guns are quite capable of doing .5 or better. I think the perentage of those that can vs those that can't are much lower but they still exist. Some custom rigs are capable of .2 or better. Some very custom riggs are going to do even better. That said, sometimes you get lucky and find a gun that shoots way better than it's average counter part. That doesn't guarantee in the hands of everyone that gun will perform the same.
As I mentioned in my previous post, I have REM 700 with factory everything that will shoot better than the average factory Remington. I have shot many groups in perfect conditions under .5 moa and I am an average shooter at best and am still learning to reload quality ammo. In the right hands, I believe this gun can shoot better than .5 all day long if the person with it had good reloading and shooting skills.
To get a real good factory shooter seems to be hit or miss. You can increase your odds by going custom or even super custom. As cycbb486 mentioned, pressure from a competition can make or break a shooter. Jerry has pointed out that wind can do the same. Those are all shooter variables. My 8 year old can turn a .2 gun into a minute of landfill rifle with ease. That doesn't mean the gun is not a .2 moa gun. It means she is a 36.0 moa shooter.
It is like anything out there. How much time, money and effort are you willing to put into it? If you have a factory gun and do everything you can to find it's true potential (bedding, reloading, good optics etc...) and it shoots .5 or better , giddy up. If not, then are you willing to go to the next step? Custom pipe, action yadda yadda yadda. If that doesn't fill your cornflakes bowl, dive deaper into the rabbit hole and see how good it gets.
Back to the original question. I believe the answer is yes. Being a gambling man though, I am not sure the odds are stacked in your favour until you start tossing some green (or in Canada red/blue/brown) at it.
my 2 cents worth.
Now someone needs to start a thread about how many shooters are capable of .5 moa or better. Now that would be an interesting and heated read
