Ordered a 90rd Drum for the AR.+ questions.


December 27, 2006, 01:35 AM
so i ordered one of those 90rd drums for my ar-15.
so here is my dilema i really want to test out the drum with a full load to make sure that it works properly all the way through. but i want to check the function of the drum without getting the barrel to to hot, i don't want to mess the thing up. i know when i do cqb drills and fire 20rds in pretty fast sucesion it is extremely hot, then i take a break to let it cool and even 20rds with a few seconds in between to realign on target while shooting at longer ranges, th barrel still gets pretty darn hot.
1)so what pace should i shoot at to achieve this mission?
2) how many rds does it take in rapid succesion to screw up a barrel just as a reference?
3) how long will it take to see a considerable change in accuracy from the barel becomming heated?
btw the rifle in question is a bushmaster 16" chrome lined barrel flat top model that ya'll have seen before. thanks!

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December 27, 2006, 03:22 AM
90 Rounds will in no way "screw up' your barrel. Ive dumped 90 rounds from a mini14 as fast as i could, and it got pretty hot(Smoke rollin off on a 85 degree day)

December 27, 2006, 03:22 AM
If you don't want to mess the rifle up,then what the heck were you thinking when you ordered a drum?
Every shot fired thru any barrel degrades the barrel. This degradation varies by caliber, powder weight and charge, bullet design, etc.-etc. And as you seem to already know, heat. So if you want to load the drum on the first of the month and not damage the barrel, the mag should last till the 15th.

However there is not much a person can do that is more fun than to see how fast you can empty a 90 round drum!

December 27, 2006, 04:21 AM
I'd recommend you sell it and use the money to buy 20's and 30's. I just think the drums are pointless, not to mention inherently less reliable. I mean, if it's for play, it's just a very expensive way to not have to reload and add a couple extra pounds to your weapon... If it's for self defense or something, you're using less than optimum equipment (and that goes without saying that if a 30 round mag isn't enough for most scenarios you are really in it deep...).

I'm just saying...

December 27, 2006, 08:33 AM
If you don't want to mess the rifle up,then what the heck were you thinking when you ordered a drum?

i guess you guys have never come close to running out of ammo in combat before huh? it changes your whole oulook on alot of things.

so are ya'll saying there are no reasons at all for a drum and the only people that have them are the people that want to screw up thier guns? what the heck kind monkey poop is that? because that is the direct opposite of what i am trying to accomplish. if the time comes and i need to dump 90rds in a hurry in some foreign land i will, but as for my personal pleasure it is something to have and something i have always wanted.
btw i hav plenty of 20-30rd mags to last me a lifetime! it was time for something different.

there are questions that haven't been answered i didn't ask what your opinion was i asked regarding facts, and answeres to my qustions.

Andrew S
December 27, 2006, 12:36 PM
The AR is designed as a battle rifle. If you got yours from a quality manufacturer you will be fine dumping two drums down the barrel without hurting it.

December 27, 2006, 12:58 PM
Your sustained rate of fire should not exceed 12-15 rounds per minute as per the M-16A2 Operator's Manual. Remember that this is for a full length (20"), mil spec barrel, and if yours does not match those specs you should adjust accordingly. The manual is not indicating that you can't fire faster, just that if you want to limit the wear to a normal level, you should stick with not firing faster than 15rpm, doing so will prematurely wear out your barrel. IMO having a 90 round mag is no big deal, just remember while shooting it to keep all your rounds on target and spend several minutes shooting that many rounds.

December 27, 2006, 01:08 PM
I'd just go for it. Get about 1000 rounds and work on your technique. You'll know things that not many people know. I'd get an E silhouette, or a couple, Put them at 100 and 150 or 200 and go to work. Keep up with the hits. Try some 20 round strings, some 30 round strings and a 90 round string....and score the hits and misses.

I'm serious.

It WILL degrade the barrel....up to a point. From now on, the upper you have shot with the drum is...the drum upper. Don't worry about it. Get another upper if you are going to do any precision shooting. I'd just make a matched set out of that upper and that drum. You might even find someone with a WORN upper and trade for it.

I wish I was a neighbor of yours and you had this toy. Shooting fast and accurately out of a 90 round drum is something I would like to experience. You'll know something most folks have never thought of. I taught shooting for the army a couple of years ago...believe me, the army guys don't get to play with this stuff, and rarely or never do they get a chance on a range to even shoot 30 rounds of rapid, aimed, accurate fire on a target.

It IS going to degrade the barrel. I'd accept that and do it anyway.

December 27, 2006, 01:14 PM
to impart here, but it reminds me of a question: Does anyone have experience with sustained full auto in hot environments?
Maybe a firefight in Vietnam or Iraq?
Those barrels must get hot.

December 27, 2006, 01:48 PM
When I was I n school, I took a bunch of people (about 14 if memory serves correct) shooting who had minimal to no shooting experience, and most of them really liked the AR. In a couple of hours that bushy CAR fired almost 900 rounds and was extremely hot. I think that we were there for about 3-4 hours, and I canít be sure of the exact round count, but one person would fire his or her mag, while some other folks were loading their mag, and others still were going inside to buy more ammo. I had no idea how much they were firing, I was just making sure that everyone was following the 4 rules, and instructing the people with no experience, and that day it was just me and another RO, the third had banged out sick.
I was less than thrilled when I saw what was, and I crap you not, a bucket full of spent 223 casings, but I was happy that we got a lot of new shooters out that day. Looking back Iím really mad that I didnít keep those casings, but I didnít reload back then.

December 27, 2006, 01:59 PM
The AR 90 round drum always looked way too lop-sided for me. You should look into the Beta-C drums, which distribute the weight a little more evenly and hold 100 rounds total.

December 27, 2006, 02:22 PM
I know that its OK to leave regular mags loaded for a long time, but what about thoes drums, or the Beta-C drums? Can you leave thoes loaded with out damaging them?

December 27, 2006, 02:42 PM
It is not running out of ammo, it is just that you can buy several 30 round mags (Cproducts w/magpul followers) for the price of one of those drums. The drum makes the rifle heavier and less easy to handle and has a reputation for hangups/failures. All you need is some way to carry 3 or 4 extra mags. If you are using 20 or 30 round mags and you have no time to reload, you are in more serious trouble than you should be.

I wouldn't worry about the rifle and barrel unless you were trying to use a target rifle or something.

Do let us know how the test goes though.

December 27, 2006, 04:03 PM
If the barrel and chamber are chrome lined, then you are pretty safe firing it as much as you want, how you want. The barrel life on those are measured in the 10's of thousands of rounds. Also, I remember reading that in some of the early fire-fights in Iraq were so intense that the soldiers noticed their M-4 barrels were red hot.

As to 90 round drums, not my cup of tea, but its your gun - have fun.

December 27, 2006, 04:22 PM
Yes, by all means, have fun in your own way. All of us should.
My opinion isn't worth much beyond my own house. :)

Andrew S
December 27, 2006, 04:23 PM
I know that its OK to leave regular mags loaded for a long time, but what about thoes drums, or the Beta-C drums? Can you leave thoes loaded with out damaging them?

Springs do not get worn out by staying compressed. If it is spring loaded then you can leave it in there forever.

December 27, 2006, 06:04 PM
First off, if you want a drum, go for. Heck, I've got a Beta, just because I can. Effecient? NOpe, but a lotta fun!

Barrels are cheap. Non chrome even cheaper.

"Sustained fire" is long term. Firing at 10 rpm will "prematurely" wear out a barrel. Have fun, blast away. Are you really trying to hold a 30K round barrel life? I've done mag dumps until my handguards melted off a few times, and that barrel is still good enough to hit milk jugs at 100M.

Bartholomew Roberts
December 27, 2006, 06:07 PM
You should be able to dump 180rds as fast as you can without reaching cookoff temperatures. Shooting like that frequently will increase throat erosion and ultimately reduce your accuracy; but even exceeding the 12-15 sustained rate of fire routinely, you should be able to get at least 6k rounds out of the barrel and probably more.

Once you get past 180rds (fired as fast as possible), you start running the risk of cook off. It probably still won't happen even then; but you need to be aware of the possibility.

According to tests run in the 1960s, you can fire a 20" lightweight chrome-lined 4150 barrel at 80 rounds per minute for 3,600 rounds before projectile instability exceeds 15 degrees of yaw. Your 16" HBAR probably has more mass than the 20" and should be somewhat comparable.

Kali Endgame
December 27, 2006, 06:45 PM
Due to a mix up in scheduling I had the opportunity to put ten mags through my A2 in about five minutes. Range went cold at 5:30 not 6. Instead of running through the live fire course again we had to get rid of the ammo. Five of us went through the squad's ammo on semi and burst. That was at CAX 2002(ended late Nov.) and then I got deployed in Jan. No problem for me, but I don't know if the A2 is different than your shooter.

December 27, 2006, 07:41 PM
Bumpfire that whole sucker! Just don't accidentally let the barrel come in contact with your wrist after you lay the gun on your tailgate to cool off and police your brass and accidentally come in contact with it while dumping your handfuls of brass on said tailgate...
Not that I'd know or anything :p

December 27, 2006, 08:05 PM
thanks guys for all the positive feedback, and thanks for the schooling! i appreciate it. the thread started off slow but i got alot of good first hand experience reviews by you guys thanks again, and i can't wait to tell you all about how the drum does.
i don't plan on doing any precision shooting with my current m4, but do plan to get another upper later on that will fill that gap.
i think the drums would suck for patrolling, and such, but would be great in a defensive postion. i can't wait to try it out!
thanks again guys!

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