Jamming Issue, need some pointers

[Siringo]

If you want high cap --but a pair of sig mags. No need to modify. Work great.

The problem I had in the beginning was the round was tipped up much --- but this was with the Aluminum mag. Some on this board have gotten aluminum to work by tweaking the feed lips.

[Jeepejeep]

I'm having the exact, same problems. All 3 mags are Bushmaster and marked SS so I assume they are stainless. It almost never jams with the mag that came with the upper but one of the new ones I just got jams with every shot and the other jams once in a while. The bolt and chamber are clean and all factory lube has been removed. How should I "tweak" the mag lips to try to eliminate this? Thanks, guys.

[Larrys1911]

I'm having the exact, same problems. All 3 mags are Bushmaster and marked SS so I assume they are stainless. It almost never jams with the mag that came with the upper but one of the new ones I just got jams with every shot and the other jams once in a while. The bolt and chamber are clean and all factory lube has been removed. How should I "tweak" the mag lips to try to eliminate this? Thanks, guys.

Jeep,

Im COMPLETELY new to this round but as a start on those two that dont work .... Take a pair of dial calipers and measure the feedlips ID on the one that works and make sure the other two are the same. also measue the length of the lips and make sure they are the same.

Thats as far as I can help with no experience with the round.....

Larry

[Texas Sheepdawg]

Here is a link to a really good priced deal on Sig Mags.
http://www.cdnninvestments.com/ar25two30maw.html
They are out of stock right now, but they have even had the
Sig mags on sale for $29.99 in the past.

[Jeepejeep]

Thank you Larry and Texas. I'll do those measurements.
I can't get those magazines because I still live in the Liberal stink hole of NY. As soon as that's remedied, I'll get some fer sure!

[FirstARinNY]

It"s been awhile but I cleaned the gun they way the links you guys sent to me(instructed me how to), (brake cleaner,ball bearing grease). First shot shot - stove pipe. Second shot with new 9 round clip- stove pipe- new box ammo, new 5 round mag- stove pipe. No mag, single shot-stove pipe. What now? First AR might be last.

[commander faschisto]

1st AR...this is almost always a magazine issue...there are previous posts about it if you use the search function. Also, could you post a similar closeup shot of the same mag, loaded, where we can see the angle that the top round is sitting at in the mag? Chances are that it is pointed upward at the tip too far. This can be adjusted.

[Hoot]

The commander is right. Here's what you do. First off, figure out how to slide the floorplate off of that mag and let the spring extend until it's relaxed while the other end is holding the follower up at the lips. What you're looking for is someone choosing to make several different mags with the same length spring to cut down on the number of springs they have to keep in stock. With the spring relaxed out of the bottom, block any more of it coming out with a finger and load it up with rounds to capacity while using that finger as a floor plate. How's the tension on the first and last few rounds? Does it feel like the amount of spring still in the magazine can reliably lift all the rounds, one by one to be picked up by the bolt? If not, slip another winding of spring in, restrain it again and repeat. I'll bet that at some point, you have more than enough spring tension to reliably deliver all the rounds up to the lips and have them reliably strip by the bolt during cycling. Experiment with your technique. Some times you can slide the floorplate almost closed and let the excess windings stick out past it, while allowing you to hand cycle each round into the chamber and extract it. The point of this exercise is to see it you have a lot more spring than you need for reliable operation as that puts a lot of unneeded pressure on the cartridges where they rest upon the lips. I usually find the point where it starts to feed all the cartridges from first to last reliably, add another winding of spring and cut the rest off. The tension in modern springs will last a lot longer than your interest in the gun.

The second and more common corrective action is to tweak the lips. Basically give them a little more bend toward the center. First off, measure the distance between them at both ends and write it down. As unorthodox as it sounds, I've had the best luck tweaking by placing the mag, lips down on a flat, hard surface. Holding the mag firmly in both hands to keep it from skewing left-right and towards and away from you. Apply downward pressure on it, forcing the lips to flex toward one another. Emphasis upon keeping them as parallel as possible to one another. Release your pressure and re-measure. if they are not closer to one another, try a little more force. You'll get a feeling for this as you go. When you've coaxed them closer and they stay that way, try hand cycling the rounds again one by one. At some point, they usually become more reliable. It's as much art as science and the rule of the day is go slow, re-checking frequently. I emphasize hand cycling because allowing the rounds to repeatedly slam into the chamber as you test, causes the bullets to pull out of the case gradually, much like an inertial bullet puller works. You don't want that. Unfortunately, hand cycling does not recreate the same environment as you experience during live fire, so at some point you'll have to test it under real-time conditions. Nevertheless, if it won't hand-cycle them reliably, they'll never cycle reliably on the firing line.

One or both of the above corrective actions work almost every time. The first magazine I got has around 10 too many windings on the spring, most of which were compressed in the bottom of the mag near the floorplate. I also applied a little tweak to boot. To me, the best approach is a little of both. Unless you intend to run your rig dirtier than the bottom of my pickup truck, you don't need excessive spring pressure.

One last step to save your brass getting sliced and diced is to smooth the inner edge of the lips as they can be quite sharp. The way to do this is a varied as your imagination. I've sanded them lightly with 400 wet-or-dry. I've used scotchbrite pads. I've used the polishing fob of a Dremel (personal favorite) loaded up with some emery compound. You get the drift. Remember to clean out any filings or abrasive before retesting.

If those corrective actions have no impact upon the problem, then you can examine other mechanical factors that may be contributing to it, but I'm betting they will.

Hoot

[gunnut]

You did say, " No mag, single shot-stove pipe." This would lead me to believe that it's not a magazine problem.
We have seen problems with misaligned gas blocks and wrong buffers & or springs.
The bolt may not be going back far enough or staying back long enough. either one will do it.
I have had the same problem when my gas block worked loose after repeated removal and install.

[BillytheKid]

You may want to double check your ejector (not extractor, ejector). If something is wrong with it, that could be causing your single shot stove pipe?

Bill