"Excessive Blow-back"

[smokjunkee]

Ok, newbie here. Just been reloading for a couple of weeks and I'm working on 38 sp. cowboy loads first. I have been working with 3.7 gr. & 4.0 gr. of W-231. I settled on the 3.7gr. for the pistols but for my carbine, which I loaded out to a longer OAL to action better, the 3.7gr. seem to have much more blowback on the case. Is this a case expansion issue? And is this a concern?
SJ

 

[JoeHatley]

The chamber in the carbine is slightly larger than the chambers in your revolvers. That's why the case isn't expanding enough to seal against the blow by. More power would help, but other than a little extra clean up, the blow by isn't hurting anything.

Good Luck...

Joe