Long Range Hunting Online Magazine


Go Back   Long Range Hunting Online Magazine > Rifles, Reloading, Optics, Equipment > Equipment Discussions


Reply

Loose mounts

 
LinkBack Thread Tools Display Modes
  #1  
Old 03-09-2013, 02:31 PM
Junior Member
 
Join Date: Jun 2012
Location: New Zealand
Posts: 12
Loose mounts

I have a Tikka T3 Lite in 7mmRM. It has a Mk4 6.5-20x50 Leupold, PRW rings, and an EGW 20MOA rail fitted. It is stock other than a rear ported muzzle brake that I had fitted about twelve months ago. Prior to fitting the brake this was a consistent 0.5 MOA shooter.

Shortly after the brake was fitted things started to go wrong. Constant slight shifts in point of impact and groups opening up to around 1.25 MOA. I wasted a lot of time, powder, and projectiles trying to figure out what had gone wrong before surrendering.

I decided to ditch the rifle and therefore reattached the much maligned 1" rings that came with it, and fitted a Leupold 3-9x40 VXI. I couldn't bring myself to sell it to someone without testing it with some factory ammo, so off to the range agin! This time with some Hornady Superformance 154 SST's. It shot three <0.8 MOA 3 shot groups!!!

Change of plans. I refitted the rail (expoxied), mounts, and Mk4, and then resighted the rifle. All good. Groups back to 0.5 MOA. Then after about twenty rounds the same wandering and opening up of groups reoccured.

This time I paid a lot more attention when stripping down the scope and mounts. I detected a very slight looseness in the rail screws. Plan B was then activated. Talley rings secured with Loctite thread lock, screws torqued to 25" lbs. Off to the range for an extended session. All good for about thirty rounds, then the screws worked loose again.

A couple of hours on google that night and a few articles were found with similar issues occurring with rear ported brakes. The pervading theory was that the dual direction recoil pulse (similar to spring piston air rifles) was the culprit. It made sense to me.

Any suggestions on securing the rail or mounts to the T3 so that this issue can be dealt with? One of the down sides to the T3's is the limited bearing surface on the receiver for the rail or mounts. It was suggested to me by a gun smith that I drill the rail and receiver and pin it with a roll pin or pins. I would rather not do that.
Reply With Quote
  #2  
Old 03-09-2013, 03:51 PM
Gold Member
 
Join Date: Aug 2011
Location: Lynchburg, TN
Posts: 735
Re: Loose mounts

The best I could find out with a Google search, the EGW base you have is aluminum. If not, my mistake. But have you considered replacing you base with a steel piccatinny from either Nightforce, Badger Ordnance or some other manufacturer that has a built in recoil lug on the base to keep the base from shifting back and forth on your base mounting screws?

We also just had a discussion on another thread where Leupold recommended not using steel rings with an aluminum base. There were varied discussions as to why Leupold would make this recommendation. Not sure that we came to any other consensus other than "Steel is harder than aluminum". But there was enough doubt in my mind that I intend to replace my Talley alumnum base with a Nightforce steel base before I mount my new scope and new Mark 4 steel rings.

You might also think about bedding your scope base to the receiver with bedding compound as I have heard other people doing.

Just my thoughts, and I could be wrong.
__________________
WHEN YOU HUNT LONG RANGE, SOME TIMES THE SHOT IS THE TROPHY.
Reply With Quote
  #3  
Old 03-09-2013, 04:48 PM
Junior Member
 
Join Date: Jun 2012
Location: New Zealand
Posts: 12
Re: Loose mounts

Thanks Nimrodmar10. Sounds like a good idea to try a steel base. I will have to see if I can get one for a Tikka in this country. Nightforce are available for half the price of the whole rifle. I might have to go to Sako Optilock Tika rings. They are only available in low though, so I will have to go smaller than 50mm objective if I go Optilock!
Reply With Quote
  #4  
Old 03-10-2013, 06:21 PM
Platinum Member
 
Join Date: Dec 2011
Location: Michigan
Posts: 1,095
Re: Loose mounts

The steel base theory I think has merit. In the meantime, you may want to try the threadlocker route one last time.

Locktite comes in different "flavors" - get one that is heavy duty.

Even if you have the heavy-duty, buy another bottle. It might be bad.

Degrease your screws and screwholes really well before attaching.

If you have already tried this, my apologies. I had an issue with a threadlocker a few years back (non-firearm). I'd hate to see you chase a high $ solution when a cheap bottle of locktite might solve your issue.

Good luck - that is a frustrating issue.
Reply With Quote
  #5  
Old 03-10-2013, 06:28 PM
Platinum Member
 
Join Date: Feb 2007
Location: Townsend, Montana.
Posts: 7,934
Re: Loose mounts

Your problem is the base and why I have made so many people upset when I say buy a good quality rail. Seen it many times.

Jeff
__________________
Reply With Quote
  #6  
Old 03-11-2013, 12:59 AM
Junior Member
 
Join Date: Jun 2012
Location: New Zealand
Posts: 12
Re: Loose mounts

I'm not sure the base is the only issue. I have the exact same one (aluminum) on another 7mmRM that is un-braked and has had over four hundred rounds sent through it. A Sendero with a 6.5-20x50 Mk4.

I'm thinking that it is probably the combination of the light rifle, heavy scope, aluminum rail, rear ported muzzle break, and lack of contact area on the receiver.

Yesterday I fired 15 rounds with the brake removed, then 18 with it refitted. It came loose after the 11th round with the brake fitted. This was after remounting with a degreased receiver, screws, and rail. Using a new bottle of thread lock.

If I can source a steel rail in this country I will give it a try, as when this rifle scope combo stays together it is extremely accurate and a joy to carry. Other wise it's Optiloks and a smaller objective scope.

At least I now know how to remove thread locked screws with out a gas torch
Reply With Quote
  #7  
Old 03-11-2013, 09:45 AM
Platinum Member
 
Join Date: Dec 2008
Location: Great Falls, MT
Posts: 4,922
Re: Loose mounts

I have a couple of rifles (in .300 Win Mags) both with muzzle brakes and EGW rail (screws thread locked and torqued) without any issues.
__________________

I voted for my "FREEDOM", "GUNS", and "MONEY" - keep the change - UNK.



"I am always proud of my country!"

"Leadership Rule #2: Don't be an @zzhole." - Maj Gen Burton Field.
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes



All times are GMT -5. The time now is 05:58 AM.


Powered by vBulletin ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Management Powered by vBadvanced CMPS
All content ©2010-2014 Long Range Hunting, LLC