This was something I always wanted to build as I really like the cartridge. My first experience was with a T/C Contender. The cartridge is pretty potent in its full bore loading as Corbon made. The round shown is a 150 Nosler Ballistic Tip just for looks sake. For this rifle, it is subsonic only, probably 220gr or 240gr SMKs with a suitable charge of PB powder.
The build was one of those that goes together in your mind perfectly but not anywhere else. This was as much a nightmare as building a AR upper can be. Certainly has the right components I thought. I can't envision any better pieces:
LT Stealth upper
LT 10.0 rail
Noveske 10.5 CQB barrel in .300 Fireball. Pistol gas system, SS, M4 cuts, 1/8 twist, tuned for subsonic only
Colt M16 MP bolt and carrier, nickle teflon coated
HK 416 type sights
EoTech 553
Gemtech quick connect for HVT suppressor
SF M900 w/ LT lever
Problem one: Gas block would not allow rail to slide over it my just a wee bit.
Solution: 1. Mill the rear of the rail
2. Just kiss the bottom edges off the GB
3. Take the GB off (it is pinned and set screwed) and reattach it IN the rail through the holes. Holy mackerel Bat-Man, #3 worked.
Problem two: Bilock does not cinch all the way down as Noveske leaves room for a washer.
Solution: Make a washer. (Sounds simple. It's NOT) Done.
Problem three: Rail is just a shade too long to allow can to attach as Gemtech pointed out. DOH!
Solution: 1. Return LT 10.0 for 9.0. They would of course do it as they're customer service is excellent but nah, too easy and I want this NOW.
2. Mill front of 10.0 down to like a 9.8. MUCH harder but I pick this.
Problem four: Bought a SF M961 for this on ARFCOM. Some guy had a remarkable deal on these. Uh, too long. I have to set it forward enough for my thumb that the can will hit it. Double DOH!
Solution: M900. Jeez, that was easy for once.
Other than that, nothing went wrong. We assembled the upper for now and will mill the rail when the can gets to the shop. In the mean time, it runs fine. I had about 40 rounds of the 220 SMKs that last clocked about 1080 out of a 18" barrel.
I have to chrono this some day but a 220-240gr SMK in close must hurt a whole bunch or at the very least ruin someone's dinner plans. The hot Corbon loads really scream but I have to be careful about stabilization because of the twist. With the coming can, this will be quiet, whisper quiet in fact. :cool:
Bonus pics. Teaser shots of KAC SR25K I'm running this weekend. Schweeeet.