AR Sponsor
Posted: 8/26/2008 2:29:48 PM EDT
|
I just got some and they don't drop free, is this normal? They do lock up fine. Thanks! (((UPDATE))) Well I got my mags from MAGPUL!  2 out of 5 drop free, so I called up they told me to sand the 2 little tabs that are on the back of the mag about 2 inches down from the feed lips one on each side of the spine. So I got out the dremel and sanded it JUST A VERY LITTLE! And what do you know.......IT WORKED!  It didn't take much at all, but it was enough to make them drop free! Any body having this problem should do this it's no biggie!
|
|
That kind of attitude won't get you any help any faster. I don't have any problems with all 30 of my Pmag's in any of my lowers, though I don't have any Armalite's. There are a few lowers with problems with tight Pmag's, most of the ones I hear about are Mega lowers so I dunno if there are any other reports of out of spec Armalite lowers. |
Thank you very much!
|
if I had to guess, I'd say the p mags were out of spec...they are...plastic... |
Ah yes forged lowers are never out of spec, because, they are.....metal. But yeah give them a call, they will usually exchange pmags that might be defective for free. |
I never had any problems with my lower before.... I think they're the mags! |
that little bit of intellectual refuse came from you, not me. The standards for rifles are a little more exacting than plastic items pumped out of the factory at 90 mph. |
And how many PMags have you tried? Or is this YET ANOTHER PMag detractor who has never touched one? Oh, and if you think that NOTHING can go wrong in a machining center or that there is NEVER a rush getting forgings machined then you have OBVIOUSLY never worked in a machine shop in your life. The great thing about molded plastic is that as long as you get the dies right up front the product is a VERY REPEATABLE clone of the die's shape. Now, since people have been used to only sheet metal mags for so long it wouldn't surprise me to find out that the magwell machining tolerances have been played with by some manufacturers firguring, "Well, there's SO MUCH clearance to that skinny mag that it is OK if we leave a little extra metal on the inside." Then, some bonehead complains that perfectly good PMags suck when in fact it is his out-of-spec lower that sucks and he just never knew if before now. Look, I LOVE metal. I have worked as a Metallurgist for a Fortune 500 company. That said there is NOTHING wrong with using plastic in a low-stress part/feature like a mag-body. BTW, 20-round PMags actually weigh MORE than the old GI straight 20 aluminum mags. Thus, the PMags are beefier and more robust. Seriously - buy a couple of PMags and try them out. I think you'll be pleasantly surprised. |
Sir, I have a question perhaps you can answer? I love my P Mags. However I'm concerned that they won't hold up as well, long term, as the Aluminum. In your opinon, can the plastic loose is strength and become brittle in the long run? |
Your not calling me a bone head are ya? I gonna send these back and if the other mags fit the same way.... then I'll just stick with them! I've heard nothing but good things about these mags, and 5 is NOT enough I would like to get more, so I'm NOT bad mouthing these mags at all!
|
All pmags are guaged internally and externally during production. In addition to this they are 100% inspected to drop free of a lower with a mag well on the tighter side of Colt specs just after final assembly. |
So tell me this, over 40 USGI mags that I have do drop free then what's going on? |
Simple Answer. The PMag is not a USGI mag. The PMag uses completely different internal and external geomentry built to function in an issue Colt M4. |
Without knowing EXACTLY which polymer they use (the FAQ just says "long fiber reinforced polymer") it is hard to say for sure. That said, let's discuss the reason some plastics "become brittle over time". A lot of Thermoplastics are, in fact, at least partially amorphous (meaning they lack long-range crystalline order). Think of a milk jug made from polyethylene - if it had crystalline order it wouldn't be transparent. Thermoplastics like polyethylene have a "glass-transition temperature" commonly referred to as Tg. Below this temperature the polymer will retain its amorphous strusture (remaining a "glass" and thus transparent). Above this temperature it will start organizing itself into greater and greater crystallinity - and get more brittle in the process. If you locally heated a polyethylene milk jug it would start to get opaque in the heated area as the crystals grew inside the material - that region would also be much easier to crack than the unheated transparent material. If certain polymers are stored in a temperature uncontrolled environment they might get cycled above and below their Tg and thus become brittle. All that said, milk jugs aren't fiber re-inforced. Long fibers do A LOT to strengthen plastics but they also interfere with the crystalline forming mechanism. Thus, a fiber-reinforced plastic that is exposed to temps above its Tg might not get any more crystalline at all (or at least not noticably so) because the reinforcement is preventing the internal re-ordering. Thus, fiber reinforcement helps prevent brittleness. Think of a fiberglass boat hull (it is a glass fiber reinforced polymer), when was the last time you heard of one of THOSE becoming brittle? And given how much people pay for a boat you'd sure hear the compaints if it happened. Seeing as how PMags have survived some VERY HOT service temps without trouble, including use in full-auto weapons, I doubt the thermal mechanism of gaining brittless is an issue. Rubber bands get brittle because they are made from natural rubber latex right from rubber trees. Natural rubber is far less stable long term than synthetic polymers we use for most things nowadays. So if your concern is based on rubber band degradation please feel reassured. Some cheap plastics get brittle over time because they are outgassing "plasticizers" that are essentially absorbed heavy organic solvents (think about how some new plastics have that funny smell). Most of these "get brittle" within a year. Thus, we'd already know if this were an issue with PMags. Besides, they don't smell funny.  Ultimately, it is going to take just as many decades for some people to be convinced that polymer PMags are good-to-go as it took for the aluminum mag to be accepted. Just as there were lots of critics of aluminum mags back in the 60's/70's from guys who though the M-14 and its steel mag was the end-all-be-all of rifledom we have a similar situation today. Tooly, I didn't mean to call "you" a bonehead. Sorry if you took it that way. |
Ok thanks.....
|
That's alittle absurd, so because my rifle is NOT a issue COLT M4 I should expect problems? When did lowers change? |
It is not absurd at all. To push the boundaries of the PMags design, the constant curve internally had to be pushed to the maximum space we had available to us within the magwell. The mission of the PMag was to be a volume supplement to USGI magazines in issue weapons. Aftermarket receivers differ greatly from manufacture to manufacture and if we were to design around all of these variables it would impact the reliability of the PMag in the issue M4s and M16s. We were not prepared to sacrifice any reliability for compatibility with non US Contract receivers. |
Very good explaination. The PMag is made from a propriety polymer blend. We estimate the PMags shelf life is in decades but time will tell how well they hold up to everything. To give you an idea on how modern polymers hold up, Glock (which uses a non reinforced Nylon blend) says that their frames will retain over 95% of their strength after ten years and can still be used safely. |
|
(((UPDATE))) Well I got my mags from MAGPUL! 2 out of 5 drop free, so I called up, they told me to sand the 2 little tabs that are on the back of the mag about 2 inches down from the feed lips one on each side of the spine. So I got out the dremel and sanded it JUST A VERY LITTLE! And what do you know.......IT WORKED! It didn't take much at all, but it was enough to make them drop free! Any body having this problem should do this it's no biggie!
|
AR Sponsor