Repairing a Remington 512 Sportsmaster

My Brother bought this Remington 512 Sportmaster a while back for a very low price. The reason the price was so low was that the gun would not cycle. It simply would not pick up any ammo from the magazine.

He asked me to take a look at it.

If you are not familiar with the Remington 512, it is a bolt action, tube magazine fed, .22 rifle. 
Remington made several versions of this bolt action in the 500 series including:

• 510 - Targetmaster: Single Shot
• 511 - Scoremaster: Detachable Box Magazine
• 512 - Sportmaster: Tubular Magazine
• 513 - Matchmaster: Detachable Box Magazine

Here is the gun:

Parts Diagram for the 500 series of rifles

A close up of the parts we will be looking at

I removed what I believed were the offending parts

I narrowed the problem to these two pieces, the carrier and cartridge stop

This is how they fit together in the gun, you can see the slotted hole in the carrier, it is supposed to move the cartridge stop when it reaches its limit of movement, this was not happening and the carrier would just slip off the peg

A close look at the peg in the cartridge stop, you can see it is rounded off and worn. I'm not sure why the factory didn't make it taller, to prevent this sort of thing from happening.

We ordered this cartridge stop/carrier assembly from a vendor on ebay

 It had some dried up oil residue stuck where the surfaces mate up.

 A kiss with the wire wheel cleaned it right up

 
here you can see the difference in the height of the peg, the new one is on the right.

I re-assmebled the cartridge stop and lifter assembly and installed them in the gun. After a function check I determined that the screws were a little too tight, they should be just a little less than snug. You can see the punch marks where the factory staked them into place after adjustment. 

After the adjustment the gun was feeding and presenting the cartridges just as it should.

If the screws back themselves out, I'll have to adjust them again and stake them or use some thread locker.