Alright, so I bought a brand new, Del-ton Sierra Ar15 in 5.56. Of course I cleaned it, put a red dot on it, and took it to the range today.
The first 30 rounds were Hornady steel match as I was sighting in the red dot. Got it sighted in with 10 rounds at 100 yards (no spotting scope of course). Slapped up a new target, next 20 rounds were nicely grouped.
After the initial 30 rounds of Hornady through the factory mag, i slapped in a DPMS mag with tula ammo. The first round did not feed and got hung up about halfway up the feed ramp. Took out the mag, tried again multiple times (same mag, 1 less round each time) and the same thing kept happening.
I figured it was the Tula ammo or the new mag, so I switched back over to the mag that worked and the Hornady Match ammo that worked. Even after I switched back, same problem!
I managed to get 1 round to feed of the hornady out of the good mag. I shot off this one round, and CLICK, failure to feed on the second round (but the gun did go into battery). Very strange.
I have little experience with AR15s but have a lot of other guns. Any insight into this problem? I've googled it and came up with "oh its your ammo" but the hornady worked perfect the first time, why not the second time around?
Should I throw a polish on the feed ramps like a 1911? Or should I send back the AR to get it looked at by the MFG?
edit: it looks like the round goes about halfway up the feed ramp and gets stuck, not allowing the bolt to come fully forward. The bolt still will not come fully forward unless the magazine is released halfway and the charging handle pulled back and released multiple times. The failure puts straight line marks on the cartridge that failed to feed.
Check your gas rings on your bolt. There are three rings on it each ring has a gap, each gap must be about 90 deg. from each other. if they are to close they will let to much gas by. and the BCG will not go all the way back to pick up the next round. will cause a short stroke.
I've gone with the one peice Gas Ring on my last few ARs, but have linedf up the old ones with the Gaps all aligned, and tested dfor Function. They still ran just fine.
Yes this can be true but with working on ARs what I have seen that if the gaps are alined and are under the bottom part of the bolt it will still work but when they are alined at the upper top of the bolt alined with the gas key the gaps let more gas pass then could cause short stroke.
Thanks guys. I appreciate the advice and admit I know little about the AR15, but, would the gas rings being misalligned have anything to do with a round not making it up the feed ramp when the rifle is manually charged on a new magazine? Using the bolt release the round just jams up on the feed ramps.
Are they the dpms magazines that came with the rifle because they are really really really bad(cheap) mags. I got two in the box. I use one as a block to hold the rifle in a clamp and I experimented with multicam spray paint patterns on the other.
Do this for me...go to your shop and buy one magpul p-mag magazine and give it a try. Then you will want to order a bunch more.
...you can also double check the gas rings. You might have lined them up while cleaning but your descriptions sound like mag problems. To me.
Check lube instructions. Some new rifles need to be run a little wet (over oiled) until they wear in. Also try a box of brass ammo. I have one that will fire everything, and another from same mfg. that prefers brass only.
Yeah that sounds like a mag problem. Get a Pmag and test it. I have several and like them. Of course I also have a bunch of old mags from the army, never had a problem with any of them.
But you need to see one of the mags that come with DPMS rifles. If they are the same as the ones I got - wow - You can tell in about 5 seconds no matter your experience - they are not quality.
OP - BEFORE you go and do something really really expensive, go get a P-Mag. You will always keep the p-mag so there is no risk and you can find them in the local shops for around $15-$20
Or should I send back the AR to get it looked at by the MFG?
thats what i would do. specially if it is free to do so.it should fire perfectly with the mag they gave you,dont except anything less.unless the manual does have some sort of "break in" instructions.i dont know anything about ar's but a factory built rifle should be ready to go(minus an initial cleaning)if you dont know much about the rifle and start "modifying it",you take a chance of voiding a warranty.
guys on here can only give advise on what they think your problem is,but it is really hard to paint a picture of the problem in words.hard to know what the problem is without seeing it.if a return cost to much or to much a hassle i would suggest pictures for the best advise.im a mechanic,i know how hard it is to diagnose mechanical problems even over the phone lol
I recently built an ar using a delton dissipator kit. It worked flawlessly until I tried some 1989 vintage Israeli surplus. It short stroked about every third round. I then tried some tula and it short stroked every round.
This ammo is just low pressure crap. I contacted del-ton and they offered to look at it. But firing pretty much any other ammo other than the two mentioned it is flawless. I haven't bothered sending it to them. I figure ill just not buy any more crap ammo. There is a good chance once this thing has a few thousand rounds through it it will work fine. If not I may open up the gas port and tinker with different buffers.
So I guess my suggestion is run a few thousand rounds through it to break it in before you bother with it.
Federal American eagle ammo from walmart works flawlessly and is almost as cheap as tula. Plus it is good brass for loading.
Ps as far as mags my kit did not have any so I bought one pmag and 20 or 30 20 round master molder mags from cdnn at 4 bucks a piece. The cheap mags work fantastically. the gun just doesn't like junk ammo.
I know some say P-mags are just the best you can buy. I have a couple they work fine in my wifes AR, but the old Australian Arms Tasmanian devil I have they won't work at all. Fine with the regular aluminum military ones, but bolt won't even close with a P-mag.
1: Try brass cased ammo. AR's were designed around it, not steel and you can have issues with brass cases sticking after firing steel and not cleaning the chamber extremely well.
As previously mentioned, go pick up some American Eagle ball and give it a try.
2: Try different magazines. Brownells, CProducts (out of business but back soon), or MagPul.
Lock the bolt to the rear insert the mag then hit the bolt release. If its feeding like that it is most likely going to be gas related possibly caused by gas rings, weak ammo or a possible gas tube leak. Inspect the carrier key and also the gas tube where it enters the gas block looking for carbon where they join together. Also are you using the magazine to support the rifle? This can occasionally cause problems especially with a cheap mag. Is the bolt locking to the rear on the last round?
if the gas rings on an ar bolt in fact needed to be aligned to cycle properly then manufacturers would have created a new gas rings system where they are permanently aligned by now. just my two cents
Most likely your AR is ammo sensitive. Try this old method. First, empty the rifle and eyeball the chamber. Make sure it is empty. Then hand rack the action and dry fire as fast as you can for about 200 times. Be sure to lube up the gun heavy first.
You will smell hot metal. That is good. You are lapping in all the parts in the action. After 200 cycles, strip, clean and lube. You will feel a difference in the action. You will not hurt the firing pin. We also need a better description of the stoppage.
Is it a classic bolt over base? Or is it a complete failure to feed? Or is the gun short stroking? Be patient, you are doing what the factory would have done if you had returned the rifle to them. Try different mags and brass case ammo only.
HB of CJ (old coot) (thousands of rebuilds and hundreds of AR builds, but long ago and far away and nobody cares today anyway including me sooss there you have it) Hee hee hee.
Private E-mail me if you want...we will get you going.
There sure is a lot of "gas system" responses in this thread... :xeye:
He said he can't get a round to load when he pushes the bolt release... it's a mag issue. The gas system doesn't come into play until after the round is fired... he can't even get the damn thing to load a round to fire it...
It could also be a feed-ramp issue. I had a Marine friend who built an M4 and brought it to me to trouble-shoot and the issue was that the feed-ramps of the barrel extension were not matched smoothly with the upper. He had not used a rifle barrel extension and M4 upper, but rather, the components were just cheap and there was a gap/they fit poorly. This allowed the tips of pointier FMJ rounds to "catch" in the crevice there and cause an issue exactly as OP describes.
Sometimes PMAG's will "mask" a poor build like this because they have their own "feed ramps", somewhat, and help control and guide the round more precisely during cycling, as compared to GI mags. They also sit a bit deeper in the weapon I believe. However, if your weapon will not function with a quality GI magazine--it's got a problem.
I fail to see how this is a gas-key, gas-ring, gas-anything issue, as well, considering a new round is stripped from the magazine and the old ejected.
The problem with steel-cased ammunition in the 5.56 platform is as follows:
Case obturation with steel-cased ammunition is not as prevalent as with brass, this means, the casings do not expand and seal the chamber as well during firing. The result is that while there is still pressure in the bore, the case will have not sealed things off. This results in: fouling blowing back into the action of the weapon, as well as into the chamber of course. Repeated firing results in more and more fouling. Eventually, there is enough gunk in the chamber to prevent extraction--especially when you switch BACK to brass-cased ammunition in the same range-session, and it gets a good grip on that fouling in the chamber...
The 5.56 has this issue where the Russian ammunition does not. This is because the 5.56 has much less "taper" to its walls, which means that any drag in the chamber will be more difficult to overcome, as more rearward movement is required to achieve clearance from the chamber walls as opposed to a more tapered design.
please, post pics of your feed ramp and magazine before you file it. Let some of the experts see what you are talking about. I really think you simply have a bad mag and crappy ammo. Use brass cases and a good mag and see what happens for awhile.
If the upper has m4 ramps but the barrel extension doesn't, that can cause feed problems. Very easy to see just by looking that the feed cuts in the upper are much larger and do not blend to the ones on the barrel extension.
Could be my problem, I don't know enough about the weapons system to know if it IS my problem or not. I wouldn't take a Ferrari back and ask for a refund because I couldn't pull 95 mph around a corner and get it 0 - 60 in the 4.2 advertised seconds in my first day driving it.
please, post pics of your feed ramp and magazine before you file it. Let some of the experts see what you are talking about. I really think you simply have a bad mag and crappy ammo. Use brass cases and a good mag and see what happens for awhile.
I'll try to get some pics up later today after I get some sleep. Hornady steel match isn't crappy ammo (though the Tula is, but I only got off 2 rounds of Tula). At least in my .45, Hornady Steel Match runs better than Winchester white box, Remington UMC, Federal, or double tap even. From my initial few rounds I got off, it was pretty darn accurate.
I do however, intend on trying out the brass first thing next time as suggest. The very sad thing is, 6 gun stores within 10 miles of home, not 1 has Pmags.
Anytime I have had a bullet get jammed into the receiver like that it has been a magazine problem. I had a 10 rd mag (hacked Bushmaster) that was especially prone to that with heavy open tipped bullets. Somewhere out there a doe is alive today becuase I didn't test out my hunting ammo in that particular mag before heading out.
I'd hesitate to start filing away at the receiver. The exterior of the receiver is anodized and heat treated; the metal underneath is not going to be as hard. I'd try the simplest explanation (a $10 magazine) first.
Alright, here are some pics of the problem. To make you all happy, I went out and bought a box of PMC brass to try this with, same problem. Note also that the FTF bullets are being pushed farther inside the case, between 1/16 - 1/8".
This happens when inserting a full mag, half full mag, 1 round 2 round mag, brass, steel. NOTE THAT THIS HAPPENS ON THE FIRST ROUND OF A MAG INSERTED, before the gun has even been fired. It happens if I ride the charging handle home to try to push the bullet in and if I let it fly with the bolt release. The below picture is where the bullet gets stuck. I can press the forward assist 2 - 3 times, and the bullet goes ever so slightly forward, then the forward assist no longer tries to engage. The only way to dislodge the round is to press the magazine release and wiggle the charging handle. The mag eventually drops loose and the bullet flops out the magwell. This happens each and every time, it is not a every other magazine thing. Replicated 20 times before taking this picture.
I believe that the lips of your magazine are bent. I find it odd that both magazines are showing signs of this. Can you look at the lips on both magazines and see if you can tell that one or both are bent, or that something has hit the tops of them, or do you yourself recall doing something that could damage them (dropping them, etc.)? How are you loading them? Could your loading technique somehow be placing inward pressure on the feed-lips?
The round is going to the right place.
The bolt is trying to strip it from the magazine.
It is unable to strip it from the magazine, regardless of the round being correctly oriented. This means that the bullet/magazine interface is causing too much friction to be overcome for whatever reason, or their geometry has been altered in such a way to create a mechanical disadvantage to the process at hand.
Possibilities:
-Bend magazine feed lip(s).
-Out of spec lower presenting magazine too high or too low. (not the most common...)
-Super weak buffer spring (doubt it...)
Since he has been trying more than one mag, I doubt it is a mag issue. It really does sound like the mag isn't presenting properly. Are you inserting the mag then slapping it twice? I know it is an old military axiom, but it does make sure it is all the way home. Especially with a new weapon, the catch may need to work in a bit. Have you tried inserting the mag with the bolt closed versus with the bolt locked back to see if it makes a difference?
Weak buffer spring is a possibility, but I have never seen that happen to be honest. Also check the bolt face for damage.
The mag not being inserted properly is a very possible thing, but a mag with only 1 round in it is VERY easy to insert correctly. This leaves us with a possibility that the lower is out of spec, however, the way the round looks to me, the magazine has presented "close enough" for the cigar, so to speak.
Something is preventing the bolt from stripping the round from the magazine. Could be any number of things at this point. The real curious factor is that a magazine worked, then did not. I am wondering if for whatever reason OP's loading technique is abusive or something? I mean, it's a long shot, but without handling the weapon, everything kindof is.
Problem solved. Let me first say, how insulting, suggesting that I did not "load the magazines correctly." Do you think I put the cartridges in backwards? Did I somehow try to load a cartridge on the tall part of the follower and use some sort of wedge to keep the bullet in there? I mean, come on. The magazine was loaded properly.
Second of all, not getting the magazine seated all the way in. Really? Has society gone so far down the toilet and intelligence degraded to the point that it is a question whether one is fully seating the magazine after numerous tries and failures to feed? The magazine was seated properly.
I fixed the problem. I took the upper into the shop and ran a .125 ball nose end mill around the edges of the rectangular notch in the barrel extension to chamfer them. It turned out very nice. I actually put a .032 radius on the outside edges of this notch rather than a true chamfer. After that, I used some needle files and a round stone to level out the feed ramps and finished them off with a soft air tool with polishing compound. It works beautifully now. No gouge marks on the round, no bullets getting pushed into cartridges, AND superb feeding even with riding the charging handle home.
It is absolutely beyond me why the barrel extension would be designed with a huge rectangular lip halfway up. You might cry and say I ruined my rifle or that it will blow up in my face. Well, after 200 rounds of Tula with no FTF or FTE, I think this case is closed. If it does end up double feeding or blowing the bolt out the side of the gun, I will be sure to post a thread on it.
Re: Del-Ton Dissipator
Had the same problem. The problem is that the dwell time of the bullet is too short from gase pick up to end of barrel to develop enough pressure to fully cycle with lightweight bullets. AR15 "light" buffer springs from Wolf Springs solves the problem.
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