Wednesday, September 16, 2009

Work on Thompson Encore

So I picked up a Thompson Encore in .300WM early 2008 and put a Leupold VX-II 3-9X50 scope on it with Leupold dual dovetail rings. I was pretty excited about the setup but just couldn't get the kind of groups I was wanting.



My first round of attempted fixes was to lap the scope rings.
http://www.youtube.com/watch?v=L4oF_07X1qU
My groups still weren't where I wanted them but I couldn't see my scope wandering anymore, so off to the next attempted fix.

Oversized hinge pin. My original didn't feel too loose, but it wasn't very much money so I ordered the over sized one and put it in, it definitely is tighter, but the groups still weren't perfect.

Next up, pillar bed the forend. I wasn't a huge fan of the feel of the plastic forend so I decided to epoxy bed it with a tight fit then put in some pillar standoffs to get the free float that I was looking for. Groups still weren't great, but the gun felt a lot better to shoot.




By now it was getting close to a hunt I was wanting the rifle for and I was running out of time to play with the gun, so I made a couple changes at once. First, I got new rings, Burris Signature rings, they have a nylon insert that not only self aligns with the scope (so no lapping required) but also is softer so when compressed will grip the scope tighter. At the same time I measured the OAL needed with the Stoney Point OAL Gauge. I switch powders to RL-22 (very popular for the .300WM) and picked up the Barnes Triple Shock bullets (primarily because they had a published distance from the ogive to the lands recomendation). I loaded up several groups of bullets with varying powders and primers with the ogive 0.050" from the lands (using my fire formed brass, not new). The combination of these changes did the trick, the gun now consistently shoots sub-MOA, touching groups at 100 when I do my part.


I have since zeroed the gun for 250 yards and all the bullets go where you point them. I think the biggest factors in getting the gun accurate were the last ones I did, scope rings that won't budge and some properly loaded ammo.

As a side note, the factory ammo only shoots so-so out of the gun, the barrel was bored too deep so factory ammo sits inside of it, giving the bullets some float between the breech and the shoulder, and thus inconsistent jump to the lands. Still good enough for most hunting, but not what I was expecting with the cost of this rifle.

I'm still debating whether it was worth the investment, it is fun to shoot and looks sharp. If I were to do it again I would have bought the frame and barrel seperately, with the barrel coming from a third party like Bergara. From my research their consistency is much higher for quality barrels.