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My first AR build...ammo question

2K views 22 replies 11 participants last post by  fsted2a 
#1 ·
I'm building my first AR (5.56, 16" mid length gas system, if that matters) and my question is which ammo should I use and which ammo should I stay away from?
Is it true that each gun will have ammo that feeds properly and some that the gun just doesn't like?
Which ammo is good? Which ammo is bad? And what makes it good or bad?
Which ammo is clean and which ammo is dirty?
....sorry, I'm a total n00b. I'm learning everything from YouTube and this forum. I have no family or friends to teach me, so I'm depending on you guys...thanks in advance!
 
#2 ·
As a general rule 'cheap' = dirty.

A little carbon never hurt a gun, being dirty is a temporary problem with an easy solution.

As for reliability, yes you will have to test different ammo to see what yours likes and doesn't like.

Some will tell you to stay away from steel cased ammo for whatever reason. But it works well for its intended purpose, it does cause slightly more barrel wear than brass ammo because of the bi-metal jack eating on the steel cased stuff.

I honestly don't think an AR gets hot enough to melt the laquer or polymer on the casing, but some would disagree.

I would still run brass if u could afford it though, American eagle is decent stuff.
 
#3 ·
sputnik1988 said:
As a general rule 'cheap' = dirty.

A little carbon never hurt a gun, being dirty is a temporary problem with an easy solution.

As for reliability, yes you will have to test different ammo to see what yours likes and doesn't like.

Some will tell you to stay away from steel cased ammo for whatever reason. But it works well for its intended purpose, it does cause slightly more barrel wear than brass ammo because of the bi-metal jack eating on the steel cased stuff.

I honestly don't think an AR gets hot enough to melt the laquer or polymer on the casing, but some would disagree.

I would still run brass if u could afford it though, American eagle is decent stuff.
Okay, so I'll look for brass...
What about grain?
I'm running a 1:7 twist (if that matters)
And I'm buying this thing for home defense and for fun at the range for not much longer than 100 yards...
 
#4 · (Edited)
Okay, so I'll look for brass...
What about grain?
I'm running a 1:7 twist (if that matters)
And I'm buying this thing for home defense and for fun at the range for not much longer than 100 yards...
Hit this thread:
http://www.firearmstalk.com/forums/f20/ar15-primer-beginners-guide-59600/
What twist rate is good for me?

The longer the projectile, the faster the twist is needed in the barrel. Nowadays, the most common rate is 1x9 (one twist per nine inches), which is optimal for stabilizing 55 grain. 1x9 means one full revolution (twist) every 9 inches. This twist will adequately stabilize and 62-69 grain bullet but may have trouble with the heavier/longer 75 grain and up bullets. I cannot be exact here because every barrel manufacturer is different, and every barrel is different. This is just a general guideline.

The second most common twist is 1x7. Most milspec barrels are 1x7 because they need to stabilize the very long tracer rounds. It will adequately handle a 55 grain projectile. And handle 80 grain bullets and everything in between. The optimal projectile is about 75 grain. It should not be used for very short projectiles i.e. 40 and 46 grain projectiles.
The third most common twist is 1x8. This is usually used by precision oriented stainless barrels. The most notable exception is S&W’s MP15, which uses this rate. My personal belief is that this is a great middle of the road rate and should be used more often. It handles the 55 grain projectiles well as well as everything up to 77 grains. You would need to test it out for yourself. It’s optimal at about the 67 grain size.
There are slower twist barrels such as 1x12 twist. These barrels are optimal for smaller projectiles, like 36 and 40 grain bullets. These are usually for varmiters that use specialized bullets for their hunting needs.
 
#5 ·
So basically as long as I buy ammo that's between 55 grain and 75 grain it will be fine?
I've heard ARs can be "finicky" with ammo..
What does this mean? How will I know if the ammo I buy isn't ideal for my rifle?
Will it jam? Not feed properly? Be inaccurate? What characteristics will I see with ammo my rifle doesn't like?
 
#6 ·
So basically as long as I buy ammo that's between 55 grain and 75 grain it will be fine?
I've heard ARs can be "finicky" with ammo..
What does this mean? How will I know if the ammo I buy isn't ideal for my rifle?
Will it jam? Not feed properly? Be inaccurate? What characteristics will I see with ammo my rifle doesn't like?
Brother your over thinking all this , buy ammo, shoot it and have fun , if you have a problem come back ;)
 
#7 ·
So basically as long as I buy ammo that's between 55 grain and 75 grain it will be fine?
I've heard ARs can be "finicky" with ammo..
What does this mean? How will I know if the ammo I buy isn't ideal for my rifle?
Will it jam? Not feed properly? Be inaccurate? What characteristics will I see with ammo my rifle doesn't like?
What I usually tell folks to do is buy a little bit of several types of ammo and try them out before buyng any brand in bulk.

Some AR's don't like some of the Russian Steel cased ammo. this can be for a variety of reasons. The chamber may not be chromed, the gas port may be a little narrow, or so far out toward teh muzzle that it does not provide adequate gas impulse to cycle the action completely. Most of the steel cased ammo is kind of on the under powered side of the spectrum. In general, Carbines and Midlength gas systems seem to be a bit more tollerant of steel cased ammo than rifle length gas systems.

Another reason to try different brands and bullet weights is to see which ones you can get the best accuracy out of. Once you find the sweet spot for your rifle, then you can stock up. If you are looking atusing your AR for home defense, I recommend trying some hollow or soft point ammo in the 50-62 grain weight range. These seem to fragment more reliably and will reduce overpentration risk inside of a home. If one brand in this weight range is not accurate, try another.

Experimenting with different ammo is part of the fun of owning an AR. Welcome to the AR world.
 
#8 ·
So basically as long as I buy ammo that's between 55 grain and 75 grain it will be fine?
I've heard ARs can be "finicky" with ammo..
What does this mean? How will I know if the ammo I buy isn't ideal for my rifle?
Will it jam? Not feed properly? Be inaccurate? What characteristics will I see with ammo my rifle doesn't like?
Your barrel and bolt can be determining factors in how "finicky" with ammo your rifle is. My personal setup has a bushy barrel and bcg, (I had 4 at one time, now down to 1 due to selling the other 3 to buy ammo) with an ARES Black lightning piston system. After that, whatever interwebz parts I could get my hands on. It doesn't care what ammo I feed it. Steel, brass, blanks, it shoots 'em all.
 
#10 ·
So basically as long as I buy ammo that's between 55 grain and 75 grain it will be fine? Pretty much.
I've heard ARs can be "finicky" with ammo. Haven't we all.
What does this mean? It depends on who you ask.
How will I know if the ammo I buy isn't ideal for my rifle? Will it jam? Not feed properly? Be inaccurate? What characteristics will I see with ammo my rifle doesn't like? I could vary from slightly larger groups to stuck cases or jams. But for the most part, you won't notice anything with most ammo.
I would stay away from large bulk purchases of steel cased ammo until you've had a chance to shoot some in smaller quantities. Some rifles eat it without a second thought, others choke on it. You really won't know till you shoot some for yourself. Just about anything else should be a non-issue.
Ask enough people and any type of gun can be "finicky."
Most properly assembled/maintained firearms will function without drama when using the correct ammo (even AR-15s.) The ones that don't are actually fairly rare.

Shoot more, worry less.
 
#11 ·
On an AR I built (my build is a sticky in the AR-15 sub-forum) I had some problems early on that turned out to be the Remington UMC ammo. AR-15's can be finicky, but will usually eat almost anything. If you're having problems focus on the magazine and the ammo choice before the rifle.

In a 1:7 twist, you should probably stick with 69-75 grains as your self defense ammo. What I really mean is that you are blessed to be able to run ammo that heavy. You get better penetration with heavier ammo.

I like Hornady TAP (75gr) and Winchester Ranger HPBT (69gr). I also own a lot of BVAC, but they seem to have disappeared. Also, I'd rather not do business with Cheaper than Diamonds anymore.

At the range, don't forget to actually shoot some of your SD ammo to check its accuracy and function, but they will be $1 per trigger pull. But you could just stick to 62 FMJ are fun (M855 penetrators are cheap). Probably even 55gr would be fine.
 
#12 ·
Brother your over thinking all this , buy ammo, shoot it and have fun , if you have a problem come back ;)
Ding ding ding. If you do this you may find that your AR will eat anything you run through it. You never know unless you try. I run all kinds of different stuff, brass, steel, brass and steel in the same mag, several different grains, etc etc. Mine has eaten everything I have run through it. I have not had one problem in about 3k rounds. I don't have a very high end rifle either. Totally stock except the hand guard and some accessories.
 
#13 ·
ccase39 said:
Ding ding ding. If you do this you may find that your AR will eat anything you run through it. You never know unless you try. I run all kinds of different stuff, brass, steel, brass and steel in the same mag, several different grains, etc etc. Mine has eaten everything I have run through it. I have not had one problem in about 3k rounds. I don't have a very high end rifle either. Totally stock except the hand guard and some accessories.
Perfect.
Reading all this crap on the forums kinda freaked me out..,
Then I reassure myself by realizing the military wouldn't use a design so "finicky".
...thanks y'all
 
#14 ·
Ask enough people and any type of gun can be "finicky."
Most properly assembled/maintained firearms will function without drama when using the correct ammo (even AR-15s.) The ones that don't are actually fairly rare.

Shoot more, worry less.
Even some of the lower priced AR's will generally eat what you run through them. Overkill, and others are right. If you got a box of ammo, don't be afraid to shoot with it. It might surprise you. It won't really hurt your gun, just might cause you to spend a little more time cleaning your rifle though.
 
#15 ·
I just bought an AR for a REALLY good price and I never asked the question, "Have you had any problems?" He was a youngin' who didn't know much and just had the vibe that told me it probably had had problems.

I noticed some red flags that could have caused problems that could EASILY be remedied by me for very little money. AR-15's are very easy machines to figure out, generally. I think he just got frustrated...just a guess, though, cuz I haven't even shot it yet.
 
#16 ·
I just bought an AR for a REALLY good price and I never asked the question, "Have you had any problems?" He was a youngin' who didn't know much and just had the vibe that told me it probably had had problems.

I noticed some red flags that could have caused problems that could EASILY be remedied by me for very little money. AR-15's are very easy machines to figure out, generally. I think he just got frustrated...just a guess, though, cuz I haven't even shot it yet.
Chris, I think you need to close a window or two. Sounds like you are posting on a different thread.:eek:
 
#17 ·
http://chicagogunsmith.com/blog/ar15-barrel-options-definitions/40/

D. Barrel Twist Rate

The twist rate of the barrel is the rate of turn the bullet will experience in a given distance. For the purposes of this article only the 223 Remington / 5.56 NATO rounds will be discussed. The information provided will prove a point which can then be applied to any of the nearly countless AR15 chamberings.

First, the twist rate, or ratio, can be defined using “1:7” as an example. What this means is the bullet will experience one complete revolution within a 7” length. Whereas a 1:9 twist rate means the bullet will experience a complete revolution within 9” of length. Which is right? They are both right depending on the needs of the user, and the intended ammunition to be shot from the barrel.

The higher the twist rate, meaning the lower the number of inches taken to complete a revolution, means the more stable the bullet will be leaving the muzzle of the barrel. However it is possible to over stabilize a bullet. For example shooting a 40 or 50 grain varmint round from a 1:7 barrel may cause the bullet to turn at such high revolutions per minute (RPM) that the copper jacket can actually be removed from the lead core. This over stabilization can cause a major loss in accuracy and a loss in ballistic performance for hunting purposes. This is why it’s important to match the barrel to the ammunition, and visa versa.

When it comes down to it, any twist rate will shoot just about any bullet, but when discussing optimization the twist rate should be matched to the ammunition you intend to shoot. The general rule of thumb used is that a 1:7 will shoot bullets in the 70 grain range the best, but will also shoot 60 grain bullets just fine and even most 50 grain bullets without any problems. 1:9 shoots varmint bullets in the 40 and 50 grain range the best, but will also shoot heavier bullets, though at longer distances the heavier bullets will become unstable and cause a loss of accuracy. 1:8 seems to be the modern trade off and is a twist rate gaining popularity. The 1:8 seems to shoot everything well. So the barrel should be matched to the bullet, and if you are not sure; you usually can’t go wrong with a 1:8.

E. Barrel Length will affect many factors on the flight of the bullet including velocity and distance. All things being equal a longer rifle barrel will generally produce more accuracy at longer distances due to the increased velocity, than a shorter pistol barrel for example. It is also important to note that barrels shorter than the carbine length 16” are sometimes considered to be controlled items by the ATF and special permission is required. One must also check short barrel rifles (SBR) with their state, county and city as SBR’s are illegal in some areas.

14.5” barrels are controlled, therefore not owned by most civilians. Though a 14.5” barrel with a permanently attached long muzzle device will usually satisfy laws regard Short Barrel Rifles(SBR). 14.5” barrels are absolutely great for CQB or urban tactical and home defense (with the proper permission). The trade off is a loss of accuracy and terminal performance at longer distances.

16” barrels are the most popular allowing for the most flexibility within the rifle, especially because they do not require any special ATF permission slips. 16” barrels are seemingly good at everything, home defense, three gun competition, most tactical situations, and will even reach out with combat accuracy and effective terminal ballistics to 300 yards or so.

18” barrels are gaining popularity. These barrels are especially popular with three gun shooters. They are usually coupled with mid length or intermediate gas systems giving a great balance of distance, velocity, and reduced recoil impulse while maintaining a manageable weight.

20” barrels were used on the original M16 rifles (the grand father of the modern civilian AR15). The longer barrel will give you more velocity which will increase the effective range of the bullet. Bench rest shooters may desire this increased accuracy thus opt for a longer barrel. However the added weight of the barrel may be a turn off for hunting or tactical purposes and may be clumsy for use in home defense or CQB.
 
#18 ·
I have 2 Ar's. One a DPMS AP4, and a Colt LE. Both carbine length. They both eat anything I feed them. However I use a good rule. When shooting tula or wolf steel case it is best to shoot that either at the end of the session, or if that is all you are shooting. Combining tula shot first, then brass can cause a jam. However I was told this after shooting both in alternating mags, with no problem, with both the DPMS, and the Colt.
I do have a propensity to lube the heck out of any semi auto guns. I know in real life, this isn't practical. I mean on the battlefield ya don't ask for a time out to lube your weapon. LOL

With a custom build, take it slow and easy at first, and see what your creation likes. I bet it will like most anything, and will when broken in a bit.
Happy shooting.
 
#19 · (Edited)
Ruger52 said:
I have 2 Ar's. One a DPMS AP4, and a Colt LE. Both carbine length. They both eat anything I feed them. However I use a good rule. When shooting tula or wolf steel case it is best to shoot that either at the end of the session, or if that is all you are shooting. Combining tula shot first, then brass can cause a jam. However I was told this after shooting both in alternating mags, with no problem, with both the DPMS, and the Colt.
I do have a propensity to lube the heck out of any semi auto guns. I know in real life, this isn't practical. I mean on the battlefield ya don't ask for a time out to lube your weapon. LOL

With a custom build, take it slow and easy at first, and see what your creation likes. I bet it will like most anything, and will when broken in a bit.
Happy shooting.
Why would brass cause problems and not steel?
Is it really the metal of the casing that's causing it? Or is it that specific ammo?
 
#20 ·
Mostly because cheap russian steel ammo is underpowered. They don't put a lot of powder in there. Since the gas system relies on gas pressure, less powder means there is less pressure, less pressure means less gas to drive the system.

Buy full power 5.56 nato ammo like m193 or m855 and shoot it back to back with the cheaper russian Tula or Wolf. You will feel a difference in recoil.
 
#21 ·
AgentTikki said:
Mostly because cheap russian steel ammo is underpowered. They don't put a lot of powder in there. Since the gas system relies on gas pressure, less powder means there is less pressure, less pressure means less gas to drive the system.

Buy full power 5.56 nato ammo like m193 or m855 and shoot it back to back with the cheaper russian Tula or Wolf. You will feel a difference in recoil.
Well he said it was the brass ammo that was causing the problems, which confused me. But I understand now.

Does this mean that piston systems will eat more ammo than a gas system? They seem to be less dependent on the gas as long as it is strong enough to push the piston all the way. Idk. Maybe my philosophy is flawed.
I'm a total n00b..
 
#22 · (Edited)
Doesn't matter if its piston or DI, both are really pistons to be honest. Both systems rely on gas driving the system. The Di system reroutes the gas down the gas tube and pushes the BCG back via the gas key. The gas is then released into the upper receiver after driving the BCG.

Pistons are all a little different but work pretty much the same, driving a rod (piston) back and cycling the bcg and venting under the handguards or by the gas block.

Either system is dependant on the size of the gas port. The hole in your barrel that reroutes gas into the gas block. If sized to small, it doesn't allow enough pressure for the gas system. If sized to large, it will provide too much pressure increasing felt recoil and increasing wear and tear on your rifle's internals.

Most manufacturers err on the side of larger ports, allowing the use of cheaper underpowered ammo.

A correctly sized gas port, lets you use just about any ammo, while minimizing felt recoil and wear and tear on your parts.

An undersized gas port, won't allow your gun to cycle effectively making your AR a single shot bolt action.

Doesn't matter if its a piston system or di, if the hole's too small it won't cycle.



I've had a couple Spikes uppers and they have been overgassed. This allowed me to shoot underpowered russian steel case ammo with just about 100% reliability (only failures where ammo related (duds)). But even tho the system was a DI midlength recoil impulse was harsh, I was even able to use a 5.8oz buffer which is heavier than a h3 buffer almost twice the mass of a standard carbine buffer. The heavier buffer did help tame it a bit, but it really slowed down the timing. It also made the muzzle hard to control so I sold them looking for something else.

High end ARs by manufacturers like LaRue, Knights Armaments and others are notorious for not running the underpowered stuff. They tuned their rifles around 5.56 nato pressures, opting to make their gas ports for those higher pressures, to smooth out recoil impulses and decreasing felt recoil.


Long story short:

Everyone gun is a little different, kinda like having a personality. Try out some underpowered stuff, try some mil spec stuff. If it runs fine with everything (and most likely it will) just shoot it and enjoy it. Take your new baby out and run a few thousand rounds through her, and take lots of pics and share your experience with us! Chances are you will not run into any issues. Take a few different types of magazines, a few different types of ammo, and a shooting buddy or two.

I bet you'll have lots of fun. Don't forget the porn!
 
#23 ·
Well he said it was the brass ammo that was causing the problems, which confused me. But I understand now.

Does this mean that piston systems will eat more ammo than a gas system? They seem to be less dependent on the gas as long as it is strong enough to push the piston all the way. Idk. Maybe my philosophy is flawed.
I'm a total n00b..
Depends on which AR, and it depends on which piston system. There are enough different piston systems out there to not blanket them all in one group. I have good luck so far with pistons, but I haven't tried them all. I think it has to do with the port like Tikki said. Sometimes the piston systems can make up for an undersize port, but it is an expensive solution for what might be a barrel or gas block problem. I like the piston as overall the ones I have installed have been easier to clean. I really didn't get into pistons to solve a problem as much as I wanted an excuse to tinker, it just worked out really well for me. Take your gun and run a few hundred rounds through it. You should be fine.
 
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