AR Sponsor
Posted: 3/13/2012 2:52:20 PM EDT
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So I have this new DPMS A15. It has the slightest wobble between the upper and lower. Im thinking about drilling and tapping two set screws, one on each side of the lower back near where it curves up to the stock, it's meatier back there. Then I'll be able to turn the set screws out slightly to kill the wobble, use a little blue loctite. Anyone see any problems with that? I'd be using a 4-40 thread screw with an allen head, pretty small but would catch the edge of the upper pretty good.
The only drawback I see is that the steel screw may mess up the upper where it hits, Im thinking of also tapping a small screw on the upper for the first screw to rub against, steel on steel. |
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Accu-wedge. They cost around $5, and work great. Don't drill into your receiver to fix a non-problem, "Slop" is normal and reportedly has no effect on accuracy or function. But I'm with you, I don't like it either.
Accu-wedge FTW 
ETA: Just missed you. It may be cheapo, but it works. I've been using one in my Bushmaster for 3 years, it still works great and hasn't given me any problems. When in doubt...keep it simple. |
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Im also thinking of a simple shim that fits over the upper where people usually put an o ring. Just kickin things around in my head waiting to go home...... I read about someone who used JB WELD. He spread a thin layer on the mating surfaces and then sanded down to a perfect fit. He claimed you couldn't tell it was there. I have no idea how it held up in the long-run. Certainly cheap and easy! |
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Yeah, I know it's normal, but Im not a fan of it. I figure for 5 bucks, I can get rid of it. Already ordered an accuwedge, just seems like a cheapo fix. Your fix is even worse. If you really like drilling your receivers, then do it like MEGA is doing it. One nylon tipped set screw in the lower receiver. 
If a slight wobble bothers you that much, sell your AR and get a bolt gun. |
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Yeah, I know it's normal, but Im not a fan of it. I figure for 5 bucks, I can get rid of it. Already ordered an accuwedge, just seems like a cheapo fix. Your fix is even worse. If you really like drilling your receivers, then do it like MEGA is doing it. One nylon tipped set screw in the lower receiver. http://www.rainierarms.com/img/shop/product/e029a29bb70ab48b5ecb9457fcf5ea6f.jpg If a slight wobble bothers you that much, sell your AR and get a bolt gun. This,,,,easy fix. |
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If the receiver wobble is something you don't want, a set screw is a better solution than a wedge, or any other item which can deteriorate or break. The o-ring on the front lug is a horrible idea. This is the hottest area (chamber) of the weapon. Last place I would put a piece of rubber.
If a piece of a wedge or o-ring finds its way into your trigger group, it will lock up the gun hard. I had some of the black Colt wedges and they started showing cracks, so out it went. I don't know about the nylon tipped screws; if the nylon tip is something that could come off easily. Sig brand AR15's use a spring plunger, and the area the plunger is has a wall to separate it from the FCG. If you do use a wedge, treat it like a replacement part with a short service life. Inspect it every time you clean your weapon and replace it very often. |
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If the receiver wobble is something you don't want, a set screw is a better solution than a wedge, or any other item which can deteriorate or break. The o-ring on the front lug is a horrible idea. This is the hottest area (chamber) of the weapon. Last place I would put a piece of rubber. If a piece of a wedge or o-ring finds its way into your trigger group, it will lock up the gun hard. I had some of the black Colt wedges and they started showing cracks, so out it went. I don't know about the nylon tipped screws; if the nylon tip is something that could come off easily. Sig brand AR15's use a spring plunger, and the area the plunger is has a wall to separate it from the FCG. If you do use a wedge, treat it like a replacement part with a short service life. Inspect it every time you clean your weapon and replace it very often. Sounds dangerous. I think I'll live with a little wobble. |
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Already ordered the nylon tipped screws, from the looks of it, the nylon cap is pretty substantial, there wont be enough movement to have it come loose, might even do away with the nylon part, From looking at the Mega lowers, its a simple 10 minute drill and tap job. Goes up right behind the grip attachment point.
I know its not a big deal to have wobble, but its equally not a big deal for the 5 bucks for the screws and the time in the shop to drill and tap, and have a rock solid rifle. Maybe some people dont care, to each his own..... |
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Already ordered the nylon tipped screws, from the looks of it, the nylon cap is pretty substantial, there wont be enough movement to have it come loose, might even do away with the nylon part, From looking at the Mega lowers, its a simple 10 minute drill and tap job. Goes up right behind the grip attachment point. I know its not a big deal to have wobble, but its equally not a big deal for the 5 bucks for the screws and the time in the shop to drill and tap, and have a rock solid rifle. Maybe some people dont care, to each his own..... It's not an issue of the cost of materials and time. The issue here is drilling into the receivers to fix something that is not broken. But like you said, to each his own. |
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It's supposed to be like that. The M-16A2 I qualified with in boot camp with was the biggest rattle-trap in the world but it was still accurate to 500M with irons. ETA: if you feel compelled to do something, at least use one of the non-invasive methods mentioned, rather than ruining the value of the firearm by drilling holes in it where there shouldn't be any. Also, have you tried shooting with the arm-in-sling method? |
| I have a great fix for this thats been proven reliable, has no changes to the receiver which I HIGHLY do not recommend altering any part of the Mil-Spec receiver, and retains all function. Completely gets rid of receiver wobble WITHOUT creating a gap as the Accu-wedge does (it creates a gap between the upper/lower due to vertical pressure). Anyone interested PM me, in about 1-2 weeks Ill have some for sale in the EE. |
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I have a great fix for this thats been proven reliable, has no changes to the receiver which I HIGHLY do not recommend altering any part of the Mil-Spec receiver, and retains all function. Completely gets rid of receiver wobble WITHOUT creating a gap as the Accu-wedge does (it creates a gap between the upper/lower due to vertical pressure). Anyone interested PM me, in about 1-2 weeks Ill have some for sale in the EE. Did you pick up a handful of o-rings from the hardware store? 
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I have a great fix for this thats been proven reliable, has no changes to the receiver which I HIGHLY do not recommend altering any part of the Mil-Spec receiver, and retains all function. Completely gets rid of receiver wobble WITHOUT creating a gap as the Accu-wedge does (it creates a gap between the upper/lower due to vertical pressure). Anyone interested PM me, in about 1-2 weeks Ill have some for sale in the EE. Did you pick up a handful of o-rings from the hardware store? Lol no, Im getting some ready but Ill post more info when I do like I said in the EE. Basically, instead of applying vertical pressure which ALL the "fixes" I have seen so far do which has its negative side (applies pressure on pins/take down pin holes and creates gap) Ive created shims that create horizontal pressure on the front pin, completely eliminating all wobble. Tested for 500 rounds and has been taken down and cleaned 4 times, still functions perfectly. Best part, no wobble OR gap ––>
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Back in '85 Gunner Connor (OIC of USMC Rifle Team) allowed the insertion of the brass liner from a stripper clip between the upper and lower at divison level matches. He correctly believed the upper transitioned as combustion ensued, and affected POA. The whole stripper clip fix was haphazzard at best, but was understood. Prior to the advent of receiver screws or marginally effective accu-wedges, I employed a technique as follows: Works extremely well, won't fail until popped off with gentle persuasion from an exacto-knife, and requires no permanent mods. The mod worked for tens of thousands of rounds, through multiple barrels, and never stretched or affected the fit of the take-down pins. To the contrary, it KEPT the pins (properly lubed) fit intact, since they were no longer rattling or clanging about during the recoil impulse. The recoil is actually progressive and jolts most when the buffer reaches its limit, cushioned by the eurethane stopper, so the pins suffer less if they are kept in tension, much like your shoulder hurts less if the rifle is held firm. |
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I have a great fix for this thats been proven reliable, has no changes to the receiver which I HIGHLY do not recommend altering any part of the Mil-Spec receiver, and retains all function. Completely gets rid of receiver wobble WITHOUT creating a gap as the Accu-wedge does (it creates a gap between the upper/lower due to vertical pressure). Anyone interested PM me, in about 1-2 weeks Ill have some for sale in the EE. Did you pick up a handful of o-rings from the hardware store? Ive created shims that create horizontal pressure on the front pin, completely eliminating all wobble. Best part, no wobble OR gap ––> Horizontal fixes usually only eliminate wobble at one pin, since the hole in the upper's rear lug is elongated horizontally by design, to compensate for variances in hole spacing between it and the host lower. |
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So I have this new DPMS A15. It has the slightest wobble between the upper and lower. The wobble you speak of is there because you don't know how to use your sling. Get off the bench and use it like a man. True! The sling applies horizontal pressure, but still allows wobble in ill fitting pairs. Tight prone not so much, sitting me'h, but kneeling sling tension is usually diminished. YMMV. The battle rifle needs loose fit in certain areas, but a well mated upper to lower has no draw-back, and reduces flyers. Why settle for a near miss with a properly donned sling if it can be avoided? |
Accu-wedges are crap. They put too much tension on the receiver pins and then only on the rear one. if the front one wobbles too, that one will still wooble. 
ON my receivers (a dalphon lower- made by Olympic arms, I believe, and a COLT upper), I HAVE ZERO MOVEMENT. and I can still take down the rifle with no tools. THe kicker is I am pretty sure the dalphon lower is NOT in spec. 
Having said that, it is your lower, do whatever you want. 
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