This is the second time in a few months my scope mount on my 300 WSM has come loose. A few months back during a range session I threw a heck of a flyer. I took hold of the scope and the back of my picatinny rail was loose. I went home and torqued it back down. It happened again last weekend but now the screws are stripped. Couldn't get them out, as they just spun. I took the rifle to my gunsmith and we were able to get the screws out. The threads on the receiver were stripped. He brought out some longer scope mount screws. At least the mount holes were tapped all the way through. The new longer screws we're just short of going into the receiver. He put Loctite on the new screws and screwed the mount back down in place. Once dried he said I should be fine. My guess if this fails he'll have to tap them 8x40.

My question is what is/was causing the screw holes to strip out?

Over torqued, bad threading job or mount forcing the rail up - clamping foot causing the separation.

Sounds to me like the original screws were too short to begin with. Sometimes manufacturers don't provide what you really need, and I think that's the case here.

I doubt it’s over torque after reading other thread. I’d guess short screws or bad receiver threads.

Why god made loctite 380

Yep going to pick up some loctite today on the way home and do the front screws. Gene made a comment about the rear screws looking a bit short.

I started bonding rail to action along with paint pen/blue loctite on threads. Biggest thing is making sure screws aren’t to long or short before hand

On a .300WSM-type magnum, particularly a lighter rifle and a heavier scope, I'd be tempted to make going 8x40 the first step in mounting it.

What receiver?

LH Winchester model 70

Do the threads of the original screws engage securely without the rail?

I’d just drill/tap it to a larger size. I have to trust all my firearms.

^ ^ ^ ^ this ^ ^ ^ ^

And degrease and loctite.
I've taken a lot of doodoo and other unsavory words for
using loctite on all scope mounting screws and ring
screws. I started that years ago when a base screw
and a ring screw came loose unbeknownst to me
during a drawing hunt years back. Made me shoot
wide and kick up dirt to the side of my deer.
It ticks off many, but that's too bad. I'd use JB Weld
or something stronger if I thought a scope would
never have to be removed.
I know of a man elsewhere who uses all steel everything
and tack welds it all together. I can guarantee that
he never had a hunt spoiled because of loose mountings.

Wow!!!!

Not many of those out there, Congrats!

The screw wobbled (has play) in the holes without the mount. Definitely the threads were stripped.

I'd drill and tap to 10-32 screws. Then measure the exact correct length the screws need to be to go almost all the way through the action. Stop the screws short about .010" of the bolt. This could be grind to fit screws, but that's the way it goes sometimes. It's a milling machine job, not a drill press job.

I bought a Tikka CTR, used, years ago that had this problem. The action threads were stripped. Which I don't understand how. Tikka and Sako actions are harder than woodpecker lips. The 10-32 screws has had them holding for many years of hard use.

I think the factory taps 6-40. I'd go 8-40 for the first repair. A 10-40 (or a 10-32) surely would last forever but I don't know of any bases that would work with a screw that big.

Gotta open some bases for 10-32.

Some bases are made for 10-32.

I mis-wrote. 8-32 and 8-40 are screws I have on standby for scope bases.

sell the rifle

You've got more quit in you than a whole lot of people.

LH Win 70's are not easy to come by. And he'd be passing on the same problem to someone else. A problem that can be fixed.

No way would I sell this rifle. This is a custom rifle built by Chad Dixon at LongRifles Inc. I'm the one who added the mounts and rings. I'm leaning towards having them drilled out to 8X40.

send it back to Chad, let the pro fix it.

Or

Go to Lowes and get a drill and tap set and getter done

Just the correct size drill bit and a correct single tap. This isn't as difficult a job as some are making it out to be.

Difficult, No, but most wont have the machines to get the holes drilled and reamed to the correct size all while keeping things inline with the raceway and perpendicular to the action body. Good work does not come cheap, and cheap work does not come good.

How much do you and I, and Judd have invested in machines and tooling?

How many hours do you and I, and Judd have invested in learning and then getting good at it through reps?

Rhetorical questions. Don't answer either one. I don't really want to know.