M14 Forum

acpick

What twist are recent manufacture M1a Match or Super Match..??...Shot a buddy's Match with 147 grain ammo and wasn't impressed with groups at 100 yards.....best was about 2 inches....Would 168 grain or 180 grain bullets do better..??.....We are gonna try next time out.

art7

The benefit of heavier bullets is usually improved ballistic coefficient so it carries further before going sub-sonic, or that it is pushed less by wind.

At 100 yards, the 147 should do fine and be no where near the sonic boundary. I shoot 125 at 200, and it does fine.

The only other factor is barrel harmonics versus the bullet speed, so the bullet exits the muzzle as the barrel tip passes through an anti-node. Different bullets will behave differently, though different loads of the same bullet will also behave differently...

highbrow

If the 147gr bullets were fmj, thats probably the best they are going to do. Fmj are not known for stellar accuracy. A good hunting bullet would be better at short range. Many use 125-150 at short range and 168-175 at 300 and beyond.

plsmyk

If that 147gr ammo is mil-surplus ammo or commercially loaded mil-spec ammo, then that is about as good as you can expect to do. Your friend's rifle isn't limited by the barrel twist but the quality of the ammuntion you feed it. Try shooting some match quality ammo such as the Federal Gold Medal Match 168gr load and I think you'll see the rifle shoot much better.

The Springfield Supermatch rifles typically have heavy weight, 1:10 twist barrels. While some rifles may show a preference for a particular bullet weight, the 1:10 twist should shoot any quality, appropriate weight, .30 caliber bullet just fine (i.e. should exhibit better than 2 inch group performance). Quality ammo, match bullets ---> smaller groups. Mil-spec ammo ---> not so much.

win308

168 Sierra Match Kings are the best all around.

Bamban

If you are just punching paper try the 125s, 135s or 150s. Benchrest Flat Base bullets in the weight class I mentioned if you are chasing the accuracy potential of the rifle

JUGGERNAUT TACTICAL

I have a kreiger 20", 4 groove, 1:10 twist....super heavy wt. barrel. I've been working up loads for a year now.........she loves 168gr. and with hand loads shoots and avg. of .46moa, and occasionally .25moa. but this round only serves me from 0-600yds. I've been struggling to find a 175gr. to take me out to 1000yds. Yesterday I think I found it. at 100yds I shot .59MOA. Heres a pic I took yesterday of my 300yd group......2.005". I will be shooting next week at 1000yds in Vegas.......I hope it holds up!




one thing a person should experiment with, is bullet depth...........it seems to change accuracy more so, than powder charge. my rifle loves to Jump, this 180gr. is 2.75 COL.

Bamban

You are right, bullet seating depth is the final fine tuning to any load. Here is excellent write up on OCW, note step 17 for fine tuning.

http://optimalchargeweight.embarqspa...ons/4529817134

Check out some of the known OCW loads.

http://optimalchargeweight.embarqspa...pes/4533485759