Thanks for sharing this. You are not the only one to experience this issue and I suspect there are others who haven’t discovered it yet. I’ve been back and forth with both UM and Stockys. Neither company seems to want to acknowledge this is a problem.
My Rokstok Configuration: Tikka inlet, bare carbon, no scallop, heavy barrel contour, MT recoil lug installed.
Here are the measurements from my Rokstok and action. A digital depth gauge was used and all measurements are in inches:
-MT Recoil Lug Protrusion (measured): 0.103
-MT Recoil Lug Height: 0.641
-Rokstok Lug Inletting Depth: 0.541
-Lug Channel Depth in Tikka Action: 0.092
-Factory stock/lug protrusion: 0.088
-Factory lug height: 0.630
It should be quite obvious that the numbers do not add up. The lug protrusion on the Rokstok is too tall, causing the action to float above the stock’s bedding block by a hundredth. This will almost certainly cause stress on the action and lead to accuracy problems/POI shift.
To double-check, I installed the action and torqued down both action screws to 45 in-lbs. A thin feeler gauge was used to confirm the action was only contacting the stock around the rear tang.
Here is a metal feeler gauge being inserted between the stock and action until it contacted the front action screw:
View attachment 743466
In addition, I coated the bottom of the action in a thin layer of grease to check the “impression” against the stock’s bedding block. Again, only making contact at the recoil lug and rear tang.
Also note that the gap between the stock and action is small enough that you would not be able to detect this through visual inspection alone, nonetheless it is there.
I contacted UM with my findings and received the following reply:
View attachment 743468
Not being satisfied with this answer, I contacted Stocky’s and exchanged multiple emails. The first is the recoil lug protrusion maximum per Stockys:
View attachment 743470
The stock ended up going back to them for inspection and then returned to me. Here are their findings:
View attachment 743471
Not exactly the answer I was expecting. I rechecked everything with a different depth gauge and came up within a couple thousandths of my original measurements.
So now what?
In my case, I will probably just end up epoxy bedding the stock, since I also had functional issues with the bottom inletting on the Rokstok that I received.
As @Wyo_hntr did, the MT recoil lug could be replaced with a factory lug. However, since the Rokstok is inletted for the MT oversized lug, the fit is pretty sloppy and it should probably be epoxied in place.
The MT recoil lug could also be milled down for proper fit as @Overwire did in this post:
TL;DR:
There appears to a manufacturing issue on some Rokstoks where the recoil lug protrudes too much, potentially creating accuracy issues.
TL;DR # 2:
If you are ordering this stock with the expectation of a perfect drop-in installation, you may want to temper your expectations.
Hope this post is at least informative for anyone who may be having issues.
I did not measure anything, just eyeballed. So I can't say for sure it was not user error on my end. I can say that the factory recoil lug was a very tight fit with zero movement and had to be pressed into place with substantial force into the rokstok lug recess.
I also torqued my action screws to 65 inch lbs.
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