Good loads that work well in my gun may indeed work well in your gun also. There's no guarentee they will but it would not be a surprise if they worked well in your gun.
People are fond of saying it's ok in my gun but wont be in yours. Differences in chamber dimensions and such may seem to shine light on the myth and bring truth to it, but it is certainly not an established fact, and outright wrong in most cases.
There's a lot of loads that shoot well in many guns. That's why some loads are sort of standardized. Like 19.0 gr of 2400 under a 245 gr 44 Mag, or 8.5 gr of Unique under a 255 gr 45 Colt, or 42.5 gr of 4064 under a 168 308 Win., or 5.3 gr of WW-231 under a 225 gr 45. The list goes on.
If it were absolutely true that a load that shoots good in my guns will not shoot good in your gun, then the bottom would fall out of the Match ammo market. Why does Federal GMM ammo shoot so well in so many different guns? We need to stop perpetuating this myth.
Sure, there may be a gun or two out there that does not like YOUR Match load. There may even be a gun or two that doesn't like Federal GMM. lol. For the most part, good ammo is good ammo. Chances ARE good that my good load will shoot good in your gun too, at least given the similar platforms.
All of you myth-perpetuation individuals sizzle your brain on these thoughts.