View Full Version : AR15 Stock Troubles

August 23, 2009, 05:35 PM
Greetings All;

I have successfully turned a tack-driving all Colt AR15 into a basket case. The trouble began when I installed a Magpul PRS stock. The job was very straightforward and went without a hitch, and I love the adjustability of the stock. Wonderfully comfortable. The only problem is that I can no longer keep the rounds on paper at 100 yard, even with its pet load!

Has anyone on this forum ever experienced a change in accuracy on an AR15 as a result of changing the stock?

Many Thanks!

August 24, 2009, 08:05 PM
changing the stock can change your head position and ruin your natuarl point of aim. It also changes the hamonics of the rifle by aborbing more of the vibrations etc. you probbably need to get it on paper at say 50 yds then work outward. I'd use a grid type target so you will know how far you're off.
remember if your aim is off .008" it is an inch at 100 yds, at point of impact. that applies to an iron sight blade or the crosshairs on a scope. It shouldn't take long for the rifle to settle in the stock and you can work on your end of it

August 28, 2009, 04:05 PM
Chances are, whatever's affecting the accuracy was coincidental with the installation of the new stock.

August 29, 2009, 02:51 AM
In my little happy family ,all the ARs have collapsable stocks.They all are free floated,and they all give groups a bolt gun would be proud of..I cannot say what is going on,but I suspect ,as has been mentioned,there could be a face/spotweld/parralax/followthrough issue,or maybe something as simple as a less stable bench position.

I think it is likely the rattly nature of a collapsing stock will give some small increment of change.Rigid,dead stock is good.But,Not likely a basket case.

Any other changes?Load? loosened mounts,etc.

August 29, 2009, 10:23 AM
Did you have to change the buffer tube from a carbine length to longer A1 length to install the PRS stock? I bought one of the chinese knockoff copies of the PRS stock and did not notice any change at all in accuracy from the old fixed stock but did not have to change the buffer tube.

September 1, 2009, 09:25 AM
If you didn't also change the handguard or your sling hold, which could affect barrel harmonics, there's nothing in the buttstock that would change accuracy. The genius of the AR design is that accuracy is determined by bolt/barrel lockup and barrel quality/stiffness. AR's are not affected by bedding, etc. like Garand types.

Had to LOL at a recent article by a well known military gun "expert". He was extolling the fit and finish of Les Baer rifles and commented that the fit of the upper and lower receiver contributed to the excellent accuracy. Total BS; has no affect whatsoever. Baer probably uses premium barrels and that's the whole story there.

September 2, 2009, 10:02 PM
How about getting the buttstock attachment screw tight, the one that attaches the extension tube to the buttstock? I know if it is not sufficiently tight that can throw off the point of impact.

September 3, 2009, 09:10 PM
the butt screw may be too long if it came from an A2 stock.
If the buffer is striking the screw this could cause vibrations to jar the rifle.
But I don't think the bullet would still be in the barrel at that point.