Ruger SR556C at 10,000 Rounds. A Photo Essay.

[usbp379]

I would like to see it and read your thoughts on 300 BLK. I love the 147 grain round for general plinking around the farm, but I sure wish the military would contract it so prices would go down!!

I don't have a ton of rounds through my 300BLK SR556TD yet. Partially because I haven't mounted an optic on it. I need to start checking eBay and GunBroker.com for a nice used Aimpoint M4. Or maybe I'll get an MRO or Aimpoint PRO next time Optics Planet sends me a coupon code.

Anyway, the piston on the 300BLK is probably twice the diameter of the one on the 223 but is still in the mid length position on the barrel. I was concerned about the system's performance with the gas port so far away from the chamber but it seems to work. I haven't had any issues at all with supersonic or subsonic ammo with or without a suppressor. More testing is needed but, for now, the Ruger has cycled with everything. I guess the increased surface area of the piston does the trick.

As for the Blackout itself; I like the cartridge and enjoy shooting it. I think it offers an outstanding combination of performance and versatility. It is easy to switch over, easy to find (or make) brass and easy to find a good selection of powders and bullets.

I have played with loading subsonic ammo with bullets as light as 180gr and as heavy as 240gr. Generally the heaviest bullets work the best but long slender match bullets are expensive and take up powder space. One of my current favorites is 10.8gr of Accurate LT30 with a 220gr SMK. It is quiet and functions fine but is a compressed load. I can hear and feel the powder getting crunched as I seat the bullet. A bullet that has also worked well with this powder is the 220gr flat base from blackoutbullets.com but they've been out of stock now for months and months.

I have also played around quite a bit with supers loaded with 147/150gr and lighter. While the M80 ball bullets are fairly cheap I never really did like the velocities so I've pretty much standardized on Sierra 125gr Pro Hunters and Speer 125gr TNT's for my supersonic blasting ammo. Both bullets shoot well and give good velocity with H110 or Lil Gun so I can zero with either and still be more or less sighted in with the Remington/Barnes 120gr factory stuff from Wal-Mart.

Another bullet that has worked well in both the velocity and accuracy department is the 110gr Nosler. I bought a good bunch of these as factory seconds and have been well pleased.

Subsonic ammo is fun but rather pointless without a suppressor and its rainbow trajectory limit the effectiveness to 50 or 100 yards. Supersonic ammo can extend the usefulness to 200 yards or so but lighter bullets are needed to keep velocity within most bullets' expansion threshold.

This brings up the only real problem with 300BLK. Most available bullets are meant for high(er) velocity hunting cartridges like the 308 Winchester or 30-06. Someone needs to make an affordable 300BLK bullet.

Even with loading my own the ammo can get pretty expensive. Best I've found on .30 light bullets is around 18¢ each. Maybe a few cents cheaper on sale or as seconds. Heavy bullets are closer to 30¢ or more. Compare that with .22 bullets that can be bought in bulk for under a dime and the difference adds up quickly.

[usbp379]

Bump to add this video of the crown. This end of the barrel really looks pretty good and I'm betting the gun will still shoot pretty well.

[usbp379]

Here are five different groups fired this morning.

The low left group is my initial three fired from sitting at fifty yards. These are the first three fired since I had the gun all apart and the optic off. I then made some adjustments to my Aimpoint and fired three rounds to confirm adjust.

[usbp379]

After my 50yd "zero" groups I moved back to 100 yards and shot fifteen rounds prone. These were fired in 5-shot strings and I walked downrange and marked each group after firing.

First up was Federal Fusion. This went a little high right so I recorrected my optic.

[usbp379]

Next group fired was 69gr Gold Medal.

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And last group of the day. This was five rounds of the 77gr stuff from IMI.

Nice group overall. Would have been spectacular without the one high flier that went into the 69 GMM group.

[usbp379]

I also fired the same sequence of rounds through a DI AR with a 1x7 twist Ballistic Advantage pencil weight barrel. I'll post those pictures shortly. Interestingly both the piston and the DI gun seemed to shoot just a little bit tighter groups with the 77gr Israeli stuff.

So accuracy still seems to be right where it should be. Granted these groups aren't phenomenal but I am shooting at a big silhouette target and am running a non-magnified red dot. I'm certain I would have been able to turn in much tighter groups with some magnification, a solid shooting bench and a small aiming point.

With that said, the gun still seems to shoot about like it did last time I really checked in for accuracy. It has always been pretty much a 2moa gun and still seems to be holding that now.

[usbp379]

Here are some comparison photos of the same ammo fired through a DI gun with a Ballistic Advantage 16" pencil barrel. 1X7 twist and carbine gas.

Both this DI gun and the Ruger have an Aimpoint with a 2MOA dot.

Here is an overall view of my target. I fired three rounds from a slung/seated position at 50yds to confirm my 10yd zero then moved back to 100 yards.



After this I moved back to 100 yards and shot prone with a rolled up shooting pad for a rest.

Here is five rounds of Federal Fusion with a fired casing set alongside for reference:



I then fired five rounds of the 69gr Match. Again, with a casing set next to the group for an overall size reference.



Then I finished off the short range session with 77gr Israeli. As mentioned, this ammo seemed to shoot the best out of both rifles.



As with the groups fired with the piston gun above, the limiting factors are the target and the optic. But I wanted to test the guns and ammo against a target that I'll likely shoot with these guns.

So it looks like the SR is still shooting about as good as it did 5,000 rounds ago.