I've got a 16 inch barrel w/ 1:9 twist. I've only ever shot 50 and 55gr out of it (varmint grenade, v/z-max, varmageddon, bulk fmjbt, bulk spbt).
I've spent some time (not enough) doing 1/2 grain ladders of reloads for .223. Putting them thru chronographs, paper and groundhogs. Then one day... i decided to do shot accuracy ladders, negating speed (as long as it's safe). What i found was, out of my M&P15, the bullets did better the faster i pushed them. Up to a point. Once i started pushing them to the higher limit of powder, the groups started to open up again. Sure, it could have been a fluke or coincidence but it seemed consistent.
My primary use of the ar is plinking and groundhoggin. I'm pushing a group size of 0.72 inches (at 50 yards). Rifle has a fixed 3x (P-223) scope and my longest shot will be under 600 yards. 530 is furthest so far. I'm not sure i'll have much use for a heavier bullet but I'm open to ideas of why i might want to reconsider. Remember; get a book, do your own research, and be safe.. but here's my info: http://sven.ninja/ReloadingData
So my question is: Considering the above, is it worth time/effort (other than hobby fun) to check into heavier bullets?
First the disclaimer: I don't reload and I'm in way over my head here. Having said that, for what it's worth to you:
I've recently shot IMI Razor Core 5.56 with a 69 gr SMK bullet from my Ares SCR (yes, I'm in NY) with a 16.25" barrel with 1:9 twist. Using a chronograph I've recorded average muzzle velocity on this factory load at 2,828 fps with a 26 fps fastest/slowest spread. When I do my part I can get .75" groups at 100 yards from this load.
Sierra's website info on this bullet:
Sierra MatchKing Bullets Designed for Service Rifle competition in the M16A2/AR-15A2
The #1380 was introduced in 1984.
This bullet requires a barrel twist rate of 1x10" or faster.
Dia. (inches) 0.224
Weight (grains) 69
Sectional Density .196
Ballistic Coefficients and Velocity Ranges
.301 @ 2800 fps and above
.305 between 2800 and 2200 fps
.317 @ 2200 fps and below
Hope this helps.
I'm happy/glad you took the time to report on the standard deviation! Combining that with avg group size AND fps.. is like having your cake and eating it too. If that cant be improved on w/ hand loading, why bother reloading (other than cost/hobby etc).
Combine that info w/ Nikon's SPOT ON (http://spoton.nikonsportoptics.com/spoton/spoton.html#:12) and hornady's ballistics calculator (http://www.hornady.com/ballistics-resource/ballistics-calculator).... I'm super happy!
That also puts you right in the legal spot for hunting deer w/ an ar15 in maryland, even at the low end of the deviation. I wouldn't but.. it gives the minimum requirement of 1,200 foot-pounds of energy @ muzzle that maryland requires. I didn't think this was possible and ended up getting a 300blk but then just used a 308 bolt anyway. HAHAH.
If you are happy with it, don't try to fix it.
Where I live and shoot wind can be pretty effective at blowing bullets off course, I just shoot 75 grainers, it makes sight adjustments easy to have just one load.
Good point. That also makes it easier to konw what's what instead of having boxes of x, boxes of y.. etc especialy when i only have one rifle that shoots that caliber anyway. 308 on the other hand is a different story. I need to develop a load thats good for 308 bolt and functions in M1A... but thats a post/topic for another day.