different powder results in weird cycling...

[skyugo]

so i just picked up a pound of Hodgdon H4198. I had been loadign with H335, (and yes, now that i've upped my charge to 25.5 grains it seems to be much cleaner burning) but i like to try new stuff.
the H4198 allows for a much smaller charge so i figured it would be a little more economical. I loaded 40 rounds with 20.3 grains. good for about 3000 FPS out of a 20". Chrono'd about 2800 with my 16" middy.
It worked fine. no signs of excess pressure etc.
however, i noticed the gun cycled differently. with most ammo i'm barely aware of the bolt movement. with this there was almost like a delay.
I can't really say for sure if it was cycling it harder and i was feeling the buffer slam the back of the tube or what. just felt definitively different. a little more sight movement too.
my H335 loads chrono'd about 2900 on average.
55 grain hornady FMJ bullets for both loads.

i'm guessing the 4198 has a different gas port pressure. is this bad?

[skyugo]

ok.. did a little more reading.

4198 is apparently a very fast powder, and hence has low gas port pressure.

it worked 100% with my rifle... just had a definitively different feel. i'll use up what i've got, but probably not mess with this stuff again.

velocity wasn't nearly as consistent as my H335 loads anyway.