16" MPW Flex between upper and lower

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A-Game
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16" MPW Flex between upper and lower

Post by A-Game »

Hi Everyone,

My AAC 16" MPW arrived at my FFL yesterday. I purchased from Silencer Shop and transferred. Best price I could find and customer service was excellent. The ONLY problem is there is so much flex between the upper and lower receiver!!!
This is my first AR platform but I thought there would be little or no flex between the upper and lower receiver. It was the second thing I noticed when I picked it up.

Is this typical for these rifles??? I guess I was expecting tighter tolerances between the upper and lower.

I really like the rifle and I wanted my first 300 Blackout Rifle to be made by AAC. I wanted the AAC upper for the barrel, the quality NiB BCG, and the warranty. My knights rail does fit flush to the upper receiver. (If anyone was wondering)

The rifle is lighter than I thought it would be.

The knights arm. handgaurd is actually not bad at all. I just don't like the finish and I am going to need to cerekote or duracoat in the future.

The trigger is absolutely fantastic. I am going to post a youtube review as soon as I can get to it.

If this is a non fix part I am going to buy this lower and buy a LPK and forget about this lower entirely and suck up the mistake in buying the whole rifle instead of just the upper or building one out.

The rifle came with one Pmag. Gen2
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Dochartaigh
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Re: 16" MPW Flex between upper and lower

Post by Dochartaigh »

Look up the Accu Wedge (believe it's called that). It's basically a piece of rubber that you sandwich between the upper and lower that takes some/most of that play out.

The higher end lower receivers also commonly have a nylon grub screw you can raise and lower to fine-tune the fitment of different uppers on your lower.
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Re: 16" MPW Flex between upper and lower

Post by 300Blk »

It depends how much.
Mastersgt199
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Re: 16" MPW Flex between upper and lower

Post by Mastersgt199 »

Where is the looseness felt? If you have some slack at the take downs pins from forward to back that's no good send it back. Many if not all AR's have a bit of slack in the take down pin area side to side .002 to .003 is what seems to be the norm. Do you have a very small uniform gap between the upper and lower receiver? There should be a small measurable gap at around .006 to .013 between them and uniform from front to rear. The two should not touch. I would stay away for the accu wedge it puts a constant strain and pressure on the pins it really serves no purpose other than to make it harder to take down and is one of those make people feel good things if slack in the Ar bothers them, if it bothers you to the point it makes you less accurate or not feel confident in your rifle, go for it!
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Re: 16" MPW Flex between upper and lower

Post by 300Blk »

Accuwedge is pointless except to correct a really poor fit. I have never seen an AAC rifle with a loose fit, but maybe yours has one. It is hard to know if it is the rifle or your expectations, since this is your first AR. If it is out of military specs for upper/lower fit then AAC will replace it.
jryock
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Re: 16" MPW Flex between upper and lower

Post by jryock »

Take a picture (with scaling) and send it to AAC. Maybe someone was having a bad day on the QC line and let one slip by. The nice thing about the gun industry is that most manufacturers want to provide a quality product; AAC is no exception

With you being new to the AR, you may want to go into the local gun shop and ask to hold a few as a comparison. There are also some blueprints floating around that you can compare to.
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A-Game
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Re: 16" MPW Flex between upper and lower

Post by A-Game »

It fits loose laterally at the curve of the lower receiver the most more on the right side than the left. I'll call AAC Friday and discuss it with them. The take down pins don't flex, they are very easy to push out with slight pressure from my finger and I wonder if that could be the culprit. The manual shows using a bullet to push the pins out so the tolerances may be different from rifle to rifle. I'll take calipers to it. I don't know what milspec is for the fit.

The rifle may have sat for a while in inventory there is a little rust on the feed ramps. I have some Fireclean on order. Everyone who uses it swears by it.

What's killer is I have to wait till the 18th to shoot ;)

I missed having a serial number of 300 by 2! That would have been cool.
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Re: 16" MPW Flex between upper and lower

Post by 300Blk »

I am sure there is a mustang collector who wants 302.

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A-Game
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Re: 16" MPW Flex between upper and lower

Post by A-Game »

I think you just doubled my re-sell value!
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Mastersgt199
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Re: 16" MPW Flex between upper and lower

Post by Mastersgt199 »

A-Game wrote:It fits loose laterally at the curve of the lower receiver the most more on the right side than the left. I'll call AAC Friday and discuss it with them. The take down pins don't flex, they are very easy to push out with slight pressure from my finger and I wonder if that could be the culprit. The manual shows using a bullet to push the pins out so the tolerances may be different from rifle to rifle. I'll take calipers to it. I don't know what milspec is for the fit.

The rifle may have sat for a while in inventory there is a little rust on the feed ramps. I have some Fireclean on order. Everyone who uses it swears by it.

What's killer is I have to wait till the 18th to shoot ;)

I missed having a serial number of 300 by 2! That would have been cool.

Ya but 302 is a great little motor/number!!
Can you post a picture of exactly where you are concerned with the movement? The take-down pins and the take-down hole usually exhibit about .002 difference and yes unless overly tight you should be able to push and the pin move with your finger, you have to understand the AR is a battle gun meant to be cared for in the field with very little tool wise if any they are not custom rifles, no smart assness intended, pm me if you need some help before sending it back I've been around these Ar's since the 70's , damn I'm getting old but still like to play! I might save you some time and expense!
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