I have an opportunity to purchase a M77 tang safety (made in 86-87) chambered in 7mag. I love the M77, i already have two tang safeties (2506,243) Which both shoot great. I wasn't too sure on how well these older 7mags grouped. Does anyone have any experience with one of these?

I have one that I have gotten some decent 1-1/4 inch five shot groups with some handloads with 160 grain accubonds and R22 powder.

They can be decently accurate with the factory sporter weight barrel, but finding a load it likes is the trick.

I really should try some 140's in it, but I already have a 6.5 Mauser and a .270 shooting 140 class bullets, I want a heavier bullet from the magnum.

I'll probably re-barrel mine too a .300 I mostly bought it as a platform to build on anyway, picked it up at a gun show for $299.

Hate to tear it down though, I bet it hadn't had a box of ammo through it......

I've not had a 7mm rem mag.  But I've had 2 .300 win mags and my brother shoots a .300 win mag M77 tang safety.  I glass bedded the action and free floated the bbl on all 3 of them. Free floating tended to open up the groups slightly, but it takes any movement due to temp or moisture out of the equation.   They all ended up at around 1.5 moa, which is fine.

One of them had a horrible trigger, well, more horrible than the rest of them.  I put a Timney trigger in it, it was nice.   Unfortunately that rifle was stolen out of the SLC airport when I came home for an elk hunting trip (thus my second Ruger .300 win mag, tang safety)

FWIW,  I sold the second .300 win mag I had last year.  IIRC I sold it with a Burris 3-9 Fullfield II scope on it for about $495.  It had some miles on it, but not all that many rounds down the  tube.