I am finally going to get into the 300 BLK game, for hunting whitetail deer and pigs only, typical range will probably be 25-75 yards, max being 150 yards or so. I would like to keep my weapon as short as possible, and would prefer a 9" barrel. For those of you who have experience with this round, how much would I be gaining with a 12.5" as compared to a 9", or will a 9" be plenty for 200 yards max? Thanks.

You will be losing a little over a 100 fps in velocity between the two. My 9" MPW is plenty accurate at that ranges and have no issue hunting with Barnes black tips. Reference with speeds here - http://300aacblackout.com/resources/300-blk.pdf Page 18

9 is fine up to 300 yards with black tip.

my 10.5 is awesome unsuppressed with supers. drops them in 1 shot, actually had one bounce it hit so hard, the hog bounced off of the ground and slid into a barbed wire fence.

I run an 8.25" barrel, with a 6" SiCo Omega. It launches Blacktips at 2100f/s+

Plenty out past 100yds!

JW

Took an 8pt Texas buck at 265yds with 9"AAC upper and 125gr bullets.

This makes me feel a little better. I let my 12 year old hunt with my Micro 7 in 300BLK last year, he shot 2 deer. No blood trail on either deer. 2nd deer ran only about 30 yards and luckily my dad was with him and paid attention where she ran. My dad thought my son had missed because of the way the deer acted and ran. Found her just inside the woods on the edge of the field. No real good exit wound. The 1st deer I was with him, broad side 25 yards, deer flipped and fell on edge of field. Kicked and flopped a few minutes then it stopped. Only to be spotted walking about 50 yards to our side a little while later. I then took a chest shot behind the shoulder and the deer dropped. We sat for about 30 minutes and then we went to where he shot, (even though I knew where the deer was) cause I wanted him to track the deer. Very little to no blood at all. So we stopped trying to track and just went to where I shot the deer. As we were walking up to the deer it jumped and hauled ass. Went to where I had shot the deer and there was very little blood, tried to track her but there was nothing to track. Had several other hunters come over and no one could get on a blood trail. Now....this was with a Hornady Vmax 110g. I have since learned from my poor choice and bought some Barnes, I am hoping he has results similar to y'all's. It's such a great little rifle for a child. I was just disappointed with the blood trail. I realize the Vmax wasn't appropriate but thought we could get away with it, and we did on 1 deer.

10.5" killed plenty does out to 150 thus far, tactx bullets.

Check your laws for big game in some states SBR's are illegal.