Are magnum primers needed for AA#7 and AA#9?

[alpha6164]

Some loading data i see say mag primers are a must and i see lots of info that mag primers may just increase pressure more than do much of anything else. What is the consensus here on these two powders?

[jeffreybehr]

The use of magnum primers does increase peak pressures and velocities, but they should be used by us amateurs (without pressure-testing equipment) only if they were used by the testing organization. Substituting a magnum primer for a standard one could increase pressures to dangerous levels.

[FLSlim]

+1 I've never used mag primers for any powder in the 10 and from what I read they would only marginally boost velocity. If you choose to experiment with them, follow standard practice of starting with lite loads, increase a couple of tenths per batch of 10 rds, and look for pressure signs telling you to stop and back off.

[Mike5560]

Don't see why just standard large primers wouldn't be good enough for any 10mm load, since .40 S&W uses small primers just fine.

[cwb]

I have tested my hot #9 loads with both and didn't see enough difference to make it worth the cost difference.