The flat back receivers were the WORST for warping during heat treat, especially the single shot versions. When the round receivers came out, they changed the method of heat treat to reduce distortion.
The flat back receivers were known for not being quite "flat" because they were finished on a belt sander after machining the flat.
Aside from that, I have found no difference in accuracy from long or short or single shot vs. repeater.
I once ran a test involving 4 different actions; long action single shot, long action repeater, short action single shot and short action repeater, and one barrel and the same 10 cases. I shot 5-5shot groups from each action (25 shots total) and compared the aggs.
From the best to the worst, the difference was .058", which gives a standard deviation of .0023. Which essentially is nothing.
Bookmarks