Post Reply - Standard Products Triggers.

H&R Machine Co. with known markings of S-HR, SHR and S-HR in oval. The H and R are joined. 

Not listed is S HR (no dash with space) but I have observed.

Conn Tool & Products with a marking of S-C and SC

Able Tool Co. with known markings of SA, S-A and S=A

There have been reports of S-HB which may have been an error in reporting and really S-HR

There have been many reports of SH (no dash) and HR . The theory is that these were H&R machine with partial stamps or a stamp used during a certain period.

To make maters more interesting is that IBM used H&R Machine as well and the mark has been reported only as HR. I will have more on that in a separate post.

This information was pulled from data sheets going back 40 years. Today we have the advantage of digital photography as well as an easy medium for sharing.

To add to the confusion Springfield Armory also produced a trigger with the SA marking. We have a clue as how to tell the difference, but would also like pictures of these as well to compare to the Able Tool Co. SA marking as well as the machining marks. 

If you have any of these unknown marks please let me us know so we can better scrutinize the markings.

Currently I have S HR(space with no dash), S-C and S-A as well as what I believe to be a Springfield SA

 I would be interested in borrowing or purchasing the others to photograph and compare machine marks.