The 1911 guns have very long firing pin throw. That can make up for a lot of priming sins. Try the following experiment:
Pick out a couple dozen cases. Deprime them and clean the primer pockets with a tool made for the job or the flat blade of a small screwdriver. The little metal handle ones sold by Radio Shack are good because they are straight sided. I won't recommend the primer pocket depth uniforming tools for this, as I would for a rifle case, because LP primer pockets are about 0.010" shallower than LR primer pockets, so the tools will cut to deep for pistol.
Once you have the pockets clean, prime them. Use the depth probe that sticks out from the back end of your caliper beam to measure how deep the the primers are in the pockets. You want them 0.003"-0.005" below flush. By trial and error, find the right seating pressure to land them there. Ideally they will be at least 0.003" deeper than they were when the primer anvils touched down in the primer pocket, but that's more measuring to achieve. The Forster Co-ax press priming tool just aims for 0.005" for all primers (sometimes 0.004" after spring-back) and it works well to set the bridge of the priming mix between the primer cup and anvil. What you are doing is optimizing ignition sensitivity.
Now finish charging these rounds and try them. If you still have failures to fire you need to examine the gun. Check firing pin protrusion (ask Ruger what it should be), and that the barrel-cylinder gap isn't too small (indicating a cylinder too far forward) with a feeler gauge. Should be around 0.005" give or take a thousandth. You may have a cylinder that was cut too deeply at the back. Ruger can tell you what things should measure.
Also, if you are not using Federal 150 primers, try some. They often work when others are marginal.
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Last edited by Unclenick; November 8, 2012 at 09:28 AM.
Reason: correction
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