Yes, i agree, 140g Blackhorn was not at all accurate. Yes, i agree, recoil is noticeable. What i really wanted to learn was whether the adapter, and large rifle magnum primer, would, or would not leak through. There is zero soot leaking between the primer and the adapter. This is a good result, but the resulting accuracy was awful.

Too bad the adapter, and the large rifle magnum primer, isn't as accurate as a plain old W209 primer, that leaks like a sieve. Seems strange does it not? These results make me inclined to believe the poor accuracy using the Federal 215 primer is due to inconsistent ignition.

Seems strange the leaking W209 primer provides a more consistent ignition than the tightly sealed Federal 215 primer. These results, lead me to conclude the large rifle magnum primer doesn't provide as much heat as the W209 primer.

Today, whilst fishing, during the slow times, i was pondering bullets, and powder. It seemed the next time out shooting, i will try 105g of Blackhorn powder, the Federal 215 primer, and the 300g Deep Curl. It will be instructional for me to learn whether the load will be somewhat accurate. As it stands, i believe the Federal 215 primer is not hot enough to reliably/consistently ignite 140g of Blackhorn.

The W209 primer doesn't seem to be 'strong' enough to allow the use of 140g Blackhorn, without leaking blow back. It seems one should use less powder, no matter what primer one is using.