How about pointing an AR-15 noob in the right direction

[MXD]

I finally did it, I bought my first AR last week but other than firing friends AR's, I am clueless about ammo. Its a Stag Arms model 1 (5.56 and the barrel is a 16 in 1:9 twist) so here are my questions

1. Is there any ammo I need to avoid? I am assuming any .223 or 5.56 will be fine but what's good for a fun day at the range?

2. I am finding that ammo is about .50 per round. Is that pretty typical right now?

Thanks!

 

[gene]

I finally did it, I bought my first AR last week but other than firing friends AR's, I am clueless about ammo. Its a Stag Arms model 1 (5.56 and the barrel is a 16 in 1:9 twist) so here are my questions

1. Is there any ammo I need to avoid? I am assuming any .223 or 5.56 will be fine but what's good for a fun day at the range?

2. I am finding that ammo is about .50 per round. Is that pretty typical right now?

Thanks!

Either 556 or 223 is fine 55 up to about 70 grains with the 1-9 twist for best accuracy.

About $9.00 to $10.00 a box for brass, bulk a little less and some russian vary in price.

I avoid laquer coated steel ammo on my AR's which is my own personal preference but I have friends that shoot the newer (non laquer) wolf and bear with no problems at all.

Have fun!

 

[EddieCoyle]

1. Is there any ammo I need to avoid? I am assuming any .223 or 5.56 will be fine but what's good for a fun day at the range?

2. I am finding that ammo is about .50 per round. Is that pretty typical right now?

Thanks!

Stay away from very light or very heavy bullets. You'll be fine with 55gr to 69gr bullets with a 1/9 twist.

Half a buck per round is typical in smaller quantities, you can find better deals by the case but you'll have to call around.

ETA: Gene beat me to it.

 

[MXD]

Stay away from very light or very heavy bullets. You'll be fine with 55gr to 69gr bullets with a 1/9 twist.

Is that because that's what a 1:9 barrel is spec'd for or are there other reasons to avoid those? In other words, would a round outside of the ones you mentioned be dangerous or destructive to the gun or do they just not work as well for what I will be doing (strictly plinking)

 

[vellnueve]

They won't be destructive to the barrel at all, but they won't be stable in flight.

 

[EddieCoyle]

They won't be destructive to the barrel at all, but they won't be stable in flight.

To elaborate...

For a given caliber, bullet diameter is the same. Therefore, lighter bullets are shorter than heavier bullets. Different bullet lengths stabilize at different RPM, with the barrel twist rate determining the RPM of the projectile.

You have to spin longer bullets faster for them to stabilize, so they need a 'lower' twist rate. The opposite is true for shorter bullets. So, a 1:7 twist rate will work great for a 75gr bullet, but that same bullet will keyhole when fired through a 1:12 barrel.

 

[HTRN]

It has to do with the length of the projectile. A heavier projective has to be longer, unless you are using depleted uranium.

here is a decent reference from a barrel MFGR.

http://www.riflebarrels.com/products/caliber_twist_rates.htm

 

[MXD]

So is the 1:9 on the 16 inch barrel pretty much standard?

 

[radioman]

unless you are using depleted uranium.

Where do we get this ammo these days??

 

[ScottS]

So is the 1:9 on the 16 inch barrel pretty much standard?

Yes. When the military switched to the M855 (62gr projectile) from the previous M193 (55gr) standard, they switched to twist rates of either 1:9 (optimized for the 62gr SS109 projectile, and usually found in commercial barrels) or 1:7 (optimized to also stabilize the longer L110 tracer projectile, used in M856, and found on "true" Milspec barrels). Prior to the "A2" configuration, the rifling was a 1:12 twist to stabilize the lighter, shorter 55gr projectile.

FWIW, 95%+ of the ammo you find will be either 55gr (frequently referred to as M193) or 62gr (frequently referred to as M855, and occasionally incorrectly referred to as SS109). You will also run into some odd-duck stuff, like 75gr for long range shooting, or 45gr for varmint, but mostly you're looking at either 55 or 62gr. Both shoot fine from your 1:9 barrel.

ETA: Excellent Prvi M193 ammo is available at $359/1K from a couple of places online. PM me if you want the suppliers. I don't think I'm supposed to say them. (Shhhh...it's a secret)

 

[cekim]

Where do we get this ammo these days??

Iraq and Afghanistan, but its "once fired"...

 

[Jay G]

FWIW, my Bushmaster *HATES* SP ammo. Maybe this is a noob thing that "everyone" already knows, but I thought I'd pass it on.

That way, maybe you won't buy a couple hundred rounds of it and then find out that your AR doesn't like it either...