Try e-gunparts.com
Where can you locate a parts breakdown and availability for a Sears mod. 42-103-2840-22 caliber rifle?
Parts for a Stevens Model 87A can be found at: http://www.e-gunparts.com/productschem.asp?chrMasterModel=089Zz87A
In my a s s h o l e
Find the serial number and google the Remington sight. They should have records of when the weapon was produced.
According to the blue book, the Ace 1 was manufactured by Cooey arms in Canada. I have 1 also and can find no more information.
A Remongton 510 .22 cal single shot rifle can be worth from $100-$1200 depending on the care and condition of the rifle. These rifles were manufactured between 1939-1962, and they are becoming very rare and harder to find.
You will have to contact Remington to find out.
Your rifle was made by F LLi Pietta, but imported by EXCAM, who is out of business. All EXCAM parts were bought by the following company- Bob's Gun Shop Inc. Po Box 200 Royal AR 71968
Made by Marlin from 1962-1965. We have some parts for that model. gunshop@nctv.com
A darn good site. http://www.urban-armory.com/diagrams/rem514.htm
Send me your email & I'll send you a scan of the manual & exploded view.