I really enjoy shooting the 223/5.56. It is a very popular cartridge that offers a ton of options in both rifles, ammunition, and reloading components. Recoil is low and relatively speaking, so is cost.
While it offers good velocity, one of the shortcomings of the cartridge is the ballistic coefficient of the bullets available. An improved BC means reaching out further at the same velocity, and less wind drift. For those that shoot inside a couple hundred yards, a good old 55 FMJ bullet will do fine but some of us want to stretch the legs a little more.
Last year I had a chance to play with the 69 grain Barnes Match Burners which are a traditional lead core bullet. One evening I was shooting at a reduced torso target, moving out with every shot, and made it all the way out to 440 yards. The next day I tried the same shot but with a 10-20 MPH gusting crosswind and things got tough. This left me a couple choices- Do better at calling the wind, increase the velocity of the bullet, or find a bullet with a better BC.
Barnes claims a BC of .339 which isn't bad considering the 69 grain Sierra MatchKing is .302 but I was introduced to a new Sierra bullet at SHOT this year, the Tipped Matchking. This bullet has a claimed .375 BC while the 77 SMK is 372. What this means is I get a bullet that I can push faster than the 77 but will give me the same BC. Faster means a flatter trajectory making it easier to range, and will be in the air for a shorter amount of time thereby reducing the affect that wind has on it.
So I decided to give it a try on paper. The rifle I used is the Tikka Sporter with 1:8 twist, 24 inch barrel on a bipod and rear bag.
First group of the day.
As a warmup I used Hornady 68 BTHP in processed and annealed Lake City brass. 22.5 IMR 8208 XBR, CCI BR4, average velocity was 2731 FPS with no signs of pressure. Overall Length was basically seating into the rifle lands and single feeding the rounds. All loaded on my new Co-Ax press (thank you Patty!) with Redding dies.
Upper right is shot #3 that I pulled.
Group size without shot #3 is .652 - .224 = .428" Not too bad for a bullet that costs 18 cents a piece.
Next string was shot with Lapua brass and Sierra Tipped Match King bullets. These bullets were seated to magazine length- 2.240" Spread is 1.43 - .224 = 1.206"
I am not sure why the shot dispersion was so bad. Maybe I was getting out of the groove and pushing the gun around. It was a little windy but I don't think it would affect the trajectory that much.
Next group was better but not by much
Another group shot with the 68 BTHP and the best group of the day at .386" Not bad with annealed range pickup LC brass! Left to right is still probably me and wind.
Last group with the TMK's. This one, without my yanked #2 shot came in at .456" and is starting to give me hope for this bullet.
I definitely need to spend some more time on the bench with this round. While I think it holds promise, I need to decide if the extra cost is worth it. The Hornady 68 BTHP is 18 cents each, Barnes 69 MB is 20 cents, and for just a little better BC the Sierra 69 TMK is 27 cents each. More to come...