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Barrett Adjustable Rings

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Category: Mounts & Accessories
Forum Name: Rings and bases
Forum Description: Any brand or type of ring or base
URL: http://www.opticstalk.com/forum_posts.asp?TID=8139
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Topic: Barrett Adjustable Rings
Posted By: Graysteel
Subject: Barrett Adjustable Rings
Date Posted: October/16/2007 at 10:48

I have a set of Barrett adjustable rings that I am thinking about testing out in a couple of weeks. Has anyone had any experience with them? I know they are made by Barrett and are heavy as can be, but I still am not 100% sure about the whole friction fit adjustments. Does anyone have any idea what the coefficient of friction is on parkerized metal surfaces? I figure I could calculate the shear force needed to knock the rings out of adjustment by figuring out how much the pressure the two crossbolts apply to the lower part of the bases. Hmm... or... I can just beat it with a rubber mallet to see if it moves and decide if I am happy with the strength.... Why do I think I am going to end up beating with it the hammer.


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Replies:
Posted By: Graysteel
Date Posted: October/16/2007 at 20:06
Ok... No responses... guess it is time to break out that hammer...

On a side note I did call the folks over at Loctite about my habit wiping a thin layer of their product onto shear surfaces such as in-between scope rings / scope body, or friction binding adjustments like the Barrett rings. I was told that the Loctite will form a chemical bond (glue) and provide additional resistance to shearing movement.

The other interesting thing they told me is that once the chemical bond is broken and the surfaces start to slide the loctite forms a mechanical interference, sort of like putting grit on the surfaces to increase friction. As such it should not inadvertently act as a lubricant between parkerized/anodized surfaces. The engineer I spoke too seemed to think it was a 'reasonable' thing to do, but lacked any specific advice.

I figured that since I was offering as advice not just doing it to my own scopes I ought to do a bit more research.


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Posted By: Graysteel
Date Posted: October/17/2007 at 08:56
 

I feel a little odd being the only person adding to this thread, but perhaps the information will be useful to someone at some point in time. Ok, last night I went down to the shop to test out the rings…

 

The test:

I made up a non-marring mounting rail out of two layers of ¼ inch thick hardboard and attached the base of the ring to the rail. From there I tightened the adjustments to about 75% of the recommended torque and measured the adjustment gap with calipers. I then cut a bit of thick leather to line the bottom of the ring and placed a section of schedule 40 pipe into the lower half of the ring. I then proceeded to tap (10 taps) on the pipe with a standard claw hammer.

 

The results:

The rings held fairly well, but not great. At the point I was tapping the pipe with the force that would approximate driving a 1.5" finishing nail into pine in 8-10 taps the rings began to shift. (about 20 thousandths). The rings were not marked at all, the friction fit simply slipped slightly. The test was repeated a couple of times. To be fair I suspect with that much impact you would likely damage most scopes before the rings themselves shifted and there was a thin film of oil (from the factory) on the shear surfaces.

 

My conclusion:

The rings are workable, but I would be careful to disassemble them and remove any oil from the shear surfaces when you get them. Next, I would make sure you tighten the binding bolts to their full specs and use a locking compound to make sure they don't loosen. And lastly, I would definitely put a drop of Loctite on the shear surfaces before tightening them down just to be safe. Oh.. and don’t beat your scope with a hammer.

 

Hope that is useful to someone.




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Posted By: cheaptrick
Date Posted: October/17/2007 at 14:46

Thanks for the write up!!

I'm sure someone browsing this forum will appreciate that info. These write ups like yours are very useful to the forum members and guests.

 

Nicely done, Sir!!

 

 

 



Posted By: Chris Farris
Date Posted: October/21/2007 at 16:39

We tested a pair on one of our Barretts with no issues.  We are http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=190165493406 - selling them now on eBay with NO RESERVE.

 



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Posted By: mike4764
Date Posted: December/19/2008 at 17:17
I use them with no problems too.


Posted By: rifle looney
Date Posted: December/20/2008 at 12:53
GREAT! now we know ,I will try this on my next install albeit on a smaller scale. firearm that is.Excellent
 p.s--- because nobody answered we got a lot of info,thanx.


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