Sharpen Your Hatchet While The World Screams

Thursday, February 1, 2018

Adventures in Rimfire pt2

As is often the case with me, we as men are afflicted with a predisposition to tinker. I read a lot about these Ruger American Rimfire rifles and it seems that great (really great) accuracy is doable with some almost free work at home.

The trigger is factory adjustable down to the 3lb zone by removing the action from the stock and turning a screw to change trigger spring tension. The trigger has a blade like Savage's Accutrigger so it is a really safe system with a tang safety that physically blocks trigger movement. It is a crisp break as supplied but for putting lead on little heads, a lighter weight is needed.

I found that a lot of people were putting lighter trigger return springs in these and getting wonderful results. So I followed this guy's video and replaced the spring with a spring from a pen, cut to length and then adjusted the tension to end up with a wonderful trigger at almost exactly 1lb on my Wheeler gauge. It is drop/bump safe and the blade has to be pressed to get it to fire. It is simply wonderful and helps put rounds to POA like a bench gun.

The trigger addressed, the rifle was way more accurate and once I found the ammo it liked (Eley Subsonic Hollow and PMC Moderator) it was doing really well at 25yds.

I read that the bolt was machined fairly rough on the bottom side of these which can result in deforming the rounds under it in the magazine when cycling the bolt. Deforming a .22 nose will result in flyers and patterns. I stoned and sanded the bottom of the bolt where it glides over the cartridges in the mag. I beveled the leading edge and rounded it slightly to remove the sharp edges as well. 

I took the magazine and reduced tension on the rotor to 4 "flats" instead of the factory adjustment which is pretty tight. This also allows the bolt to move easier while being enough tension to keep cartridges in the correct position for feeding. 

The above link recommends 6 flats for a 10-22 auto but a bolt gun does not need that level of tension. 

I also polished the magazine's feed lips and bullet guide. 

The result was SUPER slick feeding and perfect placement of rounds into the chamber. Bolt cycling is effortless and at only 60 degrees bolt lift, it is fast to operate. The bullet tips show zero scratches or scrapes now, the results should be fewer groups opened up by an odd uncalled flyer. 

Another area of needed work is keeping the action still in the stock. These rifles have aluminum blocks in the stocks and pillars to bed the action. Plastic stocks made on production lines however have to have some room to accept parts with some tolerance. The old trick of "tape bedding" can be used to see how a rifle will react to permanent bedding without taking a step that can't be reversed. 

I took aluminum HVAC tape and wrapped the bedding blocks in 2 layers to tighten the fit in the stock. This stopped all the wiggling around and should help accuracy by not allowing the action to move around when firing. 

This is what the blocks look like. They rest on brass pillars in the stock and are a friction fit. 

Plastic stocks can also be easy to flex in the front and contact the barrel. This wreaks havoc on consistency. I got out my air die grinder and a carbide bit and opened up the channel on each side and under the tip of the stock. I got about an 1/8th" gap which should keep the barrel free floating. 

If the gun shoots, I plan to upgrade to a scope with more magnification that is parallax adjustable and put the action in a Boyds laminate stock. 

To be continued.... 

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