110 FCP-HS 338 LM - poor ejection

[Twinsen]

I am very new to this caliber. 20 rounds loaded and fired. So I don't know what is normal nor if I am doing something wrong. Feel free to treat me like a toddler.


Issue:
Out of 20 rounds fired, one case ejected clear of the action. One stovepiped. Of the rest, about half dropped into the action, and half stayed on the bolt and wouldn't pop off. With the latter kind, I ran the bolt forward an inch and back to a stop several times but the bolt wouldn't give up the case. I would have to tip the case so the rim would come off the extractor.


Ammo (handloads only):
Lapua brass
Winchester LRM primers
76.6gr Hybrid 100V under 250gr SMK (shot 2 MOA)
77.6gr Hybrid 100V under 250gr SMK (shot 1.1-1.2 MOA)
All loaded to 3.681"

Load data for this caliber is sparse. I guess it's for guys that have a clue. I don't see anything for 250 SMKs. I guesstimated (science!) my data by looking at Hodgdon data for 250gr Hornady softpoints and by using Quickload software. Hodgdon says 76gr-81gr with the Hornady bullets I'm not using, and Quickload gave me a max charge of 78.5gr for the bullets I am using. I have some 285 A-Maxes as well, and there's no data for them with any powder that I can find in my manuals or Hodgdon's site. I have a pound of H100V and of US 869 for heavier bullets. I probably will not buy any more H100V as this accuracy isn't impressive and the printed velocities are low which in my experience means the accuracy sucks.

Dies:
RCBS Gold Medal Bushing Neck Sizing Die - using a 0.366 bushing
RCBS Gold Medal Seating Die

Brass:
Brand new. I see no pressure signs, no funny marks, etc. I might be overlooking something though. I've never gotten pressure signs in any reloads in any caliber and never exceeded load data. My 308 primers go flat-ish, but these primers look normal. I read that is meaningless though.


Rifle:
New 110 FCP-HS in 338 Lapua Magnum


The rifle is very loud and bothered other shooters on the line. I've never really used muzzlebrakes before, so I didn't know how pleasant they are. I only assumed they were abusive because other shooters using them are annoying and sometimes make me flinch. I lose the reticle on firing, but my shoulder tells me I'm shooting stout 12ga. Certainly nowhere as bad as 3.5" 12ga.