Rifle Scopes Era-Tac moving ?

[trophyhunter]

I was in match today and noticed my scope had slid back. I torqued the rings to 18in lbs on my 3-27 Schmidt. Through the match I started noticing that I was getting low as it went on till I zeroed two stages. Then a buddy asked is your scope moving, when I noticed it was all the way forward on the mount. I know I did not put it like this and moved it. I put it back roughly where I knew it was and went to the next stage, dialed and hit 7 of 9 shots.

Why would my mount/scope be moving ?
What are the torque specs ?

I previously had my Beast in this mount and NEVER had this issue.


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[nfoley]

Can't help with specs on that mount but holy crap that is impressive - moving it back roughly to where you thought it was and hitting 7/9 on your next stage!
I have had scopes move in the past, now I always put a witness mark with a white sharpie on ring and scope tube. When things start to go south its the first thing I look at.
What caliber you shooting?

 

[diverdon]

Spuhr suggests sprinkeling a bit of pine rosin on the rings before installing the scope. I've done that with a lot of makes since and solved a lot of problems.

 

[Fursniper]

Less than $3 for a handful.....


https://www.etsy.com/listing/2256794...FVGTfgod8IMLaQ

 

[trophyhunter]

Nfoley, I'm super OCD of where I put my scope so I was able to put it back with a small pencil mark on the bottom of the tube for this reason. I just put this scope on this Wednesday cause I had a 5-25Schmidt in it for a month and the Beast since last February 16'.

Today I was shooting 308, last week I was shooting 300wm and before that with the 5-25 & Beast mostly 6creed & 6SLR.

The mount held up well before this scope but today I was disappointed. I retorqued it to 18in-lbs then cranked to 20 just for shits.

I just got home now and noticed the mount is moving again, this time it was over 27 shots.

Never heard of using pine rosin but I'll definitely try it.


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[trophyhunter]

Does anyone know what the recommended torque specs for the Schmidt ?

I know my Premier would lock up with 20in-lbs


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[trophyhunter]

Do you know if the rosin from Brownells is the same stuff ?

I have some of that at the shop that we use to remove barrels in the vise.


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[diverdon]

I beleive any rosin will do. I'de be pretty confident of rosin I bought at Brownells.

I just bought some bowling rosin from amazon https://www.amazon.com/Ebonite-Ultra-Grip-Rosin-Bag/dp/B000MEFSHY I keep it inside a ziplock baggy in my gunsmithing box.

 

[trophyhunter]

I beleive any rosin will do. I'de be pretty confident of rosin I bought at Brownells.

I just bought some bowling rosin from amazon [video]https://www.amazon.com/Ebonite-Ultra-Grip-Rosin-Bag/dp/B000MEFSHY[/video] I keep it inside a ziplock baggy in my gunsmithing box.

Sounds good, I'm gonna try that rosin and fire about 50rds of 210g 300wm to see if any movement occurs.

I also read on the Era-Tac website that they recommend a piece of latex glove on the bottom ring for added traction. Basically shape a piece similar to the ring and it should help with heavier recoiling calibers. I didn't think 308 was one of them.

Was this incident maybe a confidence killer??
Or was I just lucky to have never experienced it with my other scope combos ?


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[dbransco]

I am interested in torque specs as well if anyone can provide them. I have not been able to find anything.

 

[KWilson]

I use 20-25 psi on my Spuhr mounts, never had a scope move on me. I always periodically check the tightness on the screws just in case one or two start to work their way loose, but it's never been an issue. I had an adjustable inclination Era-Tac mount a few years ago and used around the same torque settings with no issue. You could try thin strips of latex as they suggest, I wouldn't expect it to move with that.

 

[Schleifalot]

If you don't have rosin available, try some chalk for school blackboards. It increases friction between rings and scope.

 

[Nemain]

I run ERA TAC mounts on everything including 3 rifles chambered in .338 Lapua and never had an issues at all...

 

[trophyhunter]

I retightened it to the 17in lbs recommended and 70in lbs on the base nuts.

After that day at the match I got home and rechecked, noticed the witness mark had moved. I moved that mount to another rifle with a Beast and have yet to see it move over 200 shots from 6 creed to 308, don't know what's the difference.

I bought a Spuhr for the AXMC, put back my 3-27 with rosin, torque to specs. This weekend ran a match at Rifles Only and had not one issue. From mounting to end of match I had 40rds of 300wm, 20rds of 308 and 49 of 6 creed.

So don't know if it was the mount or scope itself ?


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