Short stroking or WTF?

You put the gas tube in upside down when you removed it?
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This is not even possible. How about we stick within the realm of possibility?

If the rifle is locking back on a single round then that narrows the possibilities down to a mag related problem. Meaning it is either the mag or the mag catch slot has been machined too low so the mag is not sitting high enough. Obviously this would be a very rare occurance so I'd take a good hard look at the mag(s).

One other thing I'd try is start out with an even or odd number of rounds in the mag. This will change the side of the mag that the second round is being presented from. See if the jam occurs more frequently one way or the other.
 
USP - dude you are cluttering the airwaves.


Is the Upper machined for M4 FeedRamps ? Sometimes (read a lot) when the Upper is machined and the Barrel Extension is not, it causes issues. As the tip of the round gets snagged in the gap and then get crunched by the Bolt and Carrier attrmpting to load it.

The Lower (ugh Oly) is a whole other issue.

Start with a known good mag.

Between the upper and lower, you've got a nightmarish frankengun.

Try to stick to FMJ ammo for the testing.
 
greentips said:
Unlike the LMT MRP - regular AR gas tube is bent and can only be installed the right way. :p
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Yeah that was a hellish day when I put mine in backwards. :p:D

I only mentioned this because this was something that I have stupidly done....:)
 
OK, I have loaded 5, 3 and 2 round mags and there seems to be no difference. I would like to focus on the lower, as I have tried 3 different mags with all the same effect. A few things I have noticed about the lower.
1. When mated to the upper it is extreamly tight, I use a small plastic hammer to set the cross pins, and to start them out of their holes.
2. I had to sand my Magpul mag to get it to insert into the mag well. My 2 metal mags fit fine. One is a Brownells, the other is unknown.

If the mag catch was machined too low, wouldn't that also cause a problem when chambering a round when cocking the rifle and using the bolt release? Mine will chamber a round as long as it is not trying to self load. I am thinking that maybe I should try yet one more mag and then think about a different brand of lower.
 
You shouldn't be using a hammer to popl the take down pins out - however, I suspect this has nothing to do with the malfunction.

Hate to be the AR snob here - but Olympic lowers and "Wilson" barreled upper ( probably something from Model 1 and other low price gunshow/internet outfits) are not exactly considered high quality products. It is very difficult to diagnose the issue over the internet if it has to do with tolerance stacking.

Your best course of action is to borrow someone's lower for some test firing and to isolate the issue to either the lower or the upper.
 
I had a buddy that had an Oly rifle and the thing was a total piece of crap.Serious jamming all the time no matter what was tried.He ended up getting rid of it because it was kinda unworkable.Not saying that is your problem but the quality of older Oly AR's is very suspect.Sounds like yours might not be up to spec if you're using hammers and having to sand things to get them to fit.
 
greentips said:
You shouldn't be using a hammer to popl the take down pins out - however, I suspect this has nothing to do with the malfunction.

Hate to be the AR snob here - but Olympic lowers and "Wilson" barreled upper ( probably something from Model 1 and other low price gunshow/internet outfits) are not exactly considered high quality products. It is very difficult to diagnose the issue over the internet if it has to do with tolerance stacking.

Your best course of action is to borrow someone's lower for some test firing and to isolate the issue to either the lower or the upper.
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I am not a fan of Olympic Arms because of the wide range of problems we experienced when we were handling their product... tolerances were poor and quality was very "iffy".

I would NOT say the same thing for Wilson barrels. They may not be high priced but they can be excellent quality... it all depends on what 'standard' they are made to.

We have had fantastic experience with our Rock River Arms product line and many of their uppers and rifles utilize barrels made for them by Wilson. Like any major manufacturer Wilson produce barrels to the end-user's specifications... so what they make for one AR manufacturer is often not the same as what the make for the next guy... both barrels can be "Wilson" barrels but they are very different products because that's what the end-user asked for and was willing to pay for. Differences in material, dimensions, tolerances, treatments, testing, etc. will have a huge affect on the end product.

I wouldn't want a Model 1 upper as they use the "cheapest" available parts/components to assemble their uppers... often resulting in poor fit and tolerance problems. We've seen some Model 1 uppers (and other brands as well) with barrels profiled so far out of spec that we couldn't install PWS Gas Piston conversions on them because the diameter of the barrel under the gas block was too small and the gas block would not seal properly.

On the other side... we never experienced any of those issues with an RRA upper (using Wilson barrels).

Just my 2 cents worth :)

Mark
 
Well guys, this really helps. Unfortunately nobody I shoot with has an AR, so I think I am just going to pick up a different lower and go from there. I bought the Oly lower on a good deal, but have not heard alot of good things about them. To be clear, I am not using a hammer on the rifle, I would classify it as light weight plastic tapping device! Pins are just a little tight, and as the parkerizing in the holes wears they are getting easier to insert and remove. Any one out there have a used lower they want to part with? I will be hunting through the EE next week.
 
Actually, let me take one step back, what lowers should I be avoiding? I am going to buy a complete lower if a good one comes by, but also would not be scared to buy a stripped and put a LPK into it. For that matter, are there LPKs that kinda suck?

Thanks guys
 
lebl468 said:
Well guys, this really helps. Unfortunately nobody I shoot with has an AR, so I think I am just going to pick up a different lower and go from there. I bought the Oly lower on a good deal, but have not heard alot of good things about them. To be clear, I am not using a hammer on the rifle, I would classify it as light weight plastic tapping device! Pins are just a little tight, and as the parkerizing in the holes wears they are getting easier to insert and remove. Any one out there have a used lower they want to part with? I will be hunting through the EE next week.
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Just remember in the future that it's only a good deal if it works. Cheaping out too much may just give you more headaches and costing more money in the end.
 
Suputin said:
This is not even possible. How about we stick within the realm of possibility?

If the rifle is locking back on a single round then that narrows the possibilities down to a mag related problem. Meaning it is either the mag or the mag catch slot has been machined too low so the mag is not sitting high enough. Obviously this would be a very rare occurance so I'd take a good hard look at the mag(s).

One other thing I'd try is start out with an even or odd number of rounds in the mag. This will change the side of the mag that the second round is being presented from. See if the jam occurs more frequently one way or the other.
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This is what you should be looking at also look at the bolt catch/release mechanism, make sure all the parts move freely.
 
have you checked the gas key and see if it is tight and staked? about the only gas problem I have ever had unless you count baked beans:redface:
 
If you hand cycle more than one round in and out does that work?

Give it locks back on an empty mag after firing, (This is correct yes?) then I think we can rule out a gas related issue.

Best bet is to try another lower.


P.S. Pictures are also very helpful...
 
I do not know any of my friendly local Weapons Techs, I think this might be out of their realm as they are used to complete rifles from one manufacturer.

As for things working to be a good deal....your telling me! I thought I could save a few bucks by slamming one of these together, but now I'm thinking off the rack might have been the way to go!

The bolt release works good, and the gas key is tight and staked.

And finally I asked around work today to see if anyone knew anyone who locally owned an AR, and no dice. I figure maybe hooking up with a Stag lower, if it doesn't solve the problem, I can always sell it...or maybe build a different rifle!
 
KevinB said:
If you hand cycle more than one round in and out does that work?

Give it locks back on an empty mag after firing, (This is correct yes?) then I think we can rule out a gas related issue.

Best bet is to try another lower.


P.S. Pictures are also very helpful...
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Yes, I can hand cycle 5 rounds through no problem, and it does lock the bolt back on an empty mag everytime, even using the bolt release will chamber a round, it is just on the ejecting a spent case/pick up new round that it sh*ts the bed.
 
One more thing I should mention is that it will NOT lock the bolt back on the Magpul mag. I thought it was just something unique to a plastic mag, but maybe not.
 
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