Today was an interesting day as I tried the Fed 215 and Rem 9 1/2M primers in my 340Wby using 250gr Accubond and 250gr Sierra SBT for velocity and accuracy while using IMR7828 and H4350. Also Rem 9 1/2L and Fed 210 primers with TAC and AA2495BR in my 358Win.
I decide to load below max a good bit to see how my 340Wby would respond in accuracy.
In the 340Wby the Rem 9 1/2M primers out performed the Fed 215 primers in accuracy and tied the Fed 215 primers in velocity. Average velocity of both primers in equal number of rounds fired with H4350 and IMR7828 was 2887fps. Rem 9 1/2M had best group and that was with the 250gr Accubond.
In my 358Win using TAC and AA2495BR the Rem 9 1/2M out performed the Fed 215 in velocity and accuracy, while the Fed 210 primer out performed the Rem 9 1/2L in accuracy but not velocity. Average velocity of Rem 9 1/2M was 2535fps and average with the Fed 215 was 2522fps. Fed 210 had the best group and that was with the 225gr Sierra using AA2495BR.
340Wby - 250gr Accubond using H4350 moving at 2846fps with Rem 9 1/2M primers, goup size was .537"
358Win - 225gr Sierra SBT using AA2495BR moving at 2361fps with 210 Fed primers, group size was .682"