Ideal Long-Range Upper and Ammo

[CrystalHunter1989]

Rather than spend the money for a .308 rifle and expensive match grade ammo, I'm thinking it's more reasonable to purchase a 20" heavy bull barrel upper chambered in 5.56 for my AR. This would serve for hunting purposes and other applications beyond the effective range of my 30-30, the only scoped weapon available to me.

What upper would you recommend and which ammo load is ideal for, say, 300 yards?

[technique]

300yrds. is a stones throw. You can use what you have.
Beyond that and for precision, I like Mk12 Mod1 uppers. You'll have to find the ammo your barrel likes.

[thatGuy]

I'm using a 1/7" twist and I can get consistant hits at 300 yards with 55gr. but the group size gets smaller with 62gr. and even smaller with 77gr.

You need to think about what range you will actually be shooting at and what effect you want to have at that range. If you want to make someones life a short living hell at 500 yards I would recommend one rifle vs if you said you wanted to constantly make called shots at the same range.

So do some soul searching as well as pacing off your AO and let us know what you find.

[RONSERESURPLUS]

Hello all, RON L here

I hate to "Parrot", what my fellow members have said here, But I feel they are dead on, a Good Tuned AR with 62GN and a other than 1 in 12 twist should be able to serve your 300 yards and under needs quite fine?  Yes, While I do prefer 308 and 3006, In an AR the 223 with the right ammo will serve the needs you have identified! Get some better ammo and give it a Try, then let us know, OK?



   RON

[leadpersuasion]

300 Yards isn't far enough to make much of difference between a 16" and a 20 " 5.56 upper using the proper ammunition. You'll just be toting around more than you need to with a 20" upper. Just invest in a 1/7 twist and if you already have that, good quality ammo like Black Hills or ASYM Precision in heavier grains just do the job.

[thekiltedpatriot]

The topic of barrel length vs twist rate vs bullet weight vs barrel life vs etc... is HIGHLY technical, so if really depends on how far down the rabbit hole you want to go, but if you decide to go with a 20" barrel, (IMO) a 1/9 twist is just fine for the greatest variety of bullet weights.  Any faster and you might blow lighter bullets apart upon exiting the barrel (seen it happen) and you'll certainly wear the barrel out much quicker.  Sounds like you are going to run 62 and heavier grains though.  A 1/12 in a 20" barrel is too slow to effectively stabilize that heavy of a bullet and 1/7 will restrict you to 55 and heavier AND wear out the barrel faster....so you're kinda stuck with a 1/9 which will be just fine for the application you stated.

That said, if you're thinking of buying/building this rifle upper AND are doing it specifically for long range accuracy as you say, I'd scrap the 20" idea and build a 24" bull version with a 1/9 twist.  Then you can reach out a lot further than 300 yards for the same amount of money.

I run several variants.  16" Carbine HBAR for multi-use and 20" Rifle HBAR free-floating for a DM all 1/9 twist.  My next AR platform will be a 24" or 26" bull at 1/9 or 1/12 (will decide twist later) because at that barrel length, your bullet velocity will be fast enough to enable that choice.

[Kentactic]

http://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi

I dont have a 62 grain bullet to measure... so i just put it in as a 1 inch long bullet (might be way off)... and with that data a 62 grain bullet wont be optimally stabilized with a 1/9 twist rate... 1/8 or better is ideal. green means good...

 i used 3200 fps as the velocity

[CrystalHunter1989]

Thanks for all the input guys. Now that I have an AR I don't really see the need to get a different gun for a purpose when I can simply alter what I already have.

[thekiltedpatriot]

Thanks for all the input guys. Now that I have an AR I don't really see the need to get a different gun for a purpose when I can simply alter what I already have.

BUT, a lower, a parts kit and butt stock can cost around $250 +/- if you shop around.  You'll already be spending $6-800 on the upper....why not build a second rifle?