I have a pretty new PSA Sabre that runs everything I have put through it perfectly, except Hornady Critical Defense .223 73 grain. With that round in particular, I get misfires about 10% of the time. I want to believe that it's just hard primers in that round in particular, but I want to make sure that there's no issue with the rifle. So I'm interested in ya'lls thoughts.

I've tried to measure firing pin protrusion with calipers, and it *seems* in spec, but I'm not confident in my ability to measure it accurately. I have a proper tool to do this on the way.

I've checked, and the hammer spring is not installed backwards.

Below are some pics of spent casings from my last range trip. Do these look like deep enough primer indents to you?

I shot one box each of 4 different types of ammo: 1) Hornady Critical Defense .223 73 grain, 2) Hornady Frontier 5.56 55 grain (m193 clone), 3) PMC X-Tac 5.56 55 grain (m193 clone), 4) AAC OTM 5.56 77 grain. I had 2 misfires with the Critical Defense, and everything else shot flawlessly.

The first attached picture has the 2 misfires from the Critical Defense. The second picture has one random spent casing each from each of the 4 types of ammunition, in the following order: 1) Critical Defense, 2) Frontier, 3) PMC, 4) AAC

To my eyes, the misfired Critical Defense rounds have pretty light primer indents, the successfully fired Critical Defense & Frontier both have somewhat light primer indents, and the PMC & AAC look better. But maybe they're still not deep enough? What do you think?

First image, misfires: https://imgur.com/bNBfL0B
Second image, spent casings: https://imgur.com/yPwxmuW

I've shot a wide range of other brands and loadings without any issues - including some others from Hornday, but I don't have any of the spent casings or pics of them to compare.