Aero M5E1 upper/lower set screw efficacy to combat play

[ISawGold]

I'm new to the AR10 platform and just picked up an Aero M5E1 upper and lower. I'm not happy with the amount of play between the two. I have ordered one of the set screws that goes through the bottom of the lower to supposedly fix the slop, but that seems like a rough fix.
Does anyone have experience with using the set screw? It works well? Does a sloppy upper and lower fit much affect the operation of the gun? I ask because there's a billet Seekins SP10 upper and lower on the Buy forum right now that I'm tempted to get if this play isn't completely fixable.

 

[XLR308]

I have tried several different ways to alleviate the issue.
The set screw works just make sure its a nylon tipped set screw so its not digging into the aluminum.
I havent personally found a little play to be an issue.
I have some upper lowers that are tight with no play and some with quite a bit.
One of them i have a JP wedge pin in and some of the best groups i have shot with it i realized the pin was loose allowing it to wiggle and move around.

 

[Praetorian_6]

So, I don't know if I'm just numb to play due to firing the sloppy weapons I'm used to in the Army, but 1) I didn't have any problem with the very minimal slop my M5E1 had, 2) the set screw that came with my completed lower was already there and I did use it just a tad, and 3) unless there's an insane amount of slop, it really won't make a difference in terms of accuracy or precision in my experience. I've shot some pretty sloppy ARs in my day, and never had a problem firing expert or getting decent shot groups. Then again, I'm not a competitive shooter, like some of the guys on this forum.

 

[ISawGold]

I have tried several different ways to alleviate the issue.
The set screw works just make sure its a nylon tipped set screw so its not digging into the aluminum.
I havent personally found a little play to be an issue.
I have some upper lowers that are tight with no play and some with quite a bit.
One of them i have a JP wedge pin in and some of the best groups i have shot with it i realized the pin was loose allowing it to wiggle and move around.

That's interesting. I was wondering if slop might even be preferable if it lets the upper vibrate a little more naturally during the shot.
Definitely with the nylon tipped set screw. https://www.opticsplanet.com/aero-precision-nylon-tipped-tension-set-screw.html

I guess my main problem is how the thing feels. You shake it by the grip and the upper/lower and the lower/stock are all rattling. Doesn't impart much confidence but I might have to get used to it.

 

[KZP]

I found the set screw setup on the m5 is meh. It can still wobble back and forth over the set screw because it's a single pivot. Once the screw is tight enough to freeze slop, you won't be able to remove the takedown pins by hand because the pressure is too much. Requires a makeshift punch and mallet.

If you are determined, a solution I've found is to use some high strength JB weld inside the takedown pin holes on the upper. Smudge it around but don't close it up completely, build up a light layer that reduces hole size so the pin won't insert. Let it cure. Then carefully enlarge the hole again until the pins are snug when pushed by hand.

 

[XLR308]

That's interesting. I was wondering if slop might even be preferable if it lets the upper vibrate a little more naturally during the shot.
Definitely with the nylon tipped set screw. https://www.opticsplanet.com/aero-precision-nylon-tipped-tension-set-screw.html

I guess my main problem is how the thing feels. You shake it by the grip and the upper/lower and the lower/stock are all rattling. Doesn't impart much confidence but I might have to get used to it.

I would guess its 90% mental and 10% function, the Veltor MUR 1A uppers i have tend to be tight with very little play also the Rock River sets i own or have handled have basically no play.
The most expensive set i have is a Wilson Combat billet set it isnt sloppy but has more play than just about any others i own but performs just as well.

 

[ISawGold]

I found the set screw setup on the m5 is meh. It can still wobble back and forth over the set screw because it's a single pivot. Once the screw is tight enough to freeze slop, you won't be able to remove the takedown pins by hand because the pressure is too much. Requires a makeshift punch and mallet.

If you are determined, a solution I've found is to use some high strength JB weld inside the takedown pin holes on the upper. Smudge it around but don't close it up completely, build up a light layer that reduces hole size so the pin won't insert. Let it cure. Then carefully enlarge the hole again until the pins are snug when pushed by hand.

Appreciate that. How were you enlarging the hole after the JB weld? I saw some guy on Youtube talk about blocking the whole thing up and then sending a drill through it.

 

[svxwilson]

JP oversized take down pins will solve slop issue quite well and no need to fuss with their older wedge pin. The wedge pin can come loose and requires more tools to take down vs the oversized pins. IMO

Below is a link to the newer undersized and oversized pins.

JP - Receivers

 

[KZP]

Appreciate that. How were you enlarging the hole after the JB weld? I saw some guy on Youtube talk about blocking the whole thing up and then sending a drill through it.

I was using a dill bit that was slightly undersized compared to each pin. Can't remember sizes, used calipers to find next smallest. Then carefully used a cordless drill to knock back the JB weld. In hindsight, I would have picked up a round file to have more control over removal.

 

[KZP]

JP oversized take down pins will solve slop issue quite well and no need to fuss with their older wedge pin. The wedge pin can come loose and requires more tools to take down vs the oversized pins. IMO

Below is a link to the newer undersized and oversized pins.

JP - Receivers

I remember looking into those. My problem was the upper receiver hole was drilled so poorly, oversized pins required to take up the slack wouldn't have fit in the lower receiver. The upper hole was like a tall oval. So double check why your upper is wobbly before getting oversized.

 

[XLR308]

JP oversized take down pins will solve slop issue quite well and no need to fuss with their older wedge pin. The wedge pin can come loose and requires more tools to take down vs the oversized pins. IMO

Below is a link to the newer undersized and oversized pins.

JP - Receivers

Thats an excellent point, the rifle with the wedge pin is a heavy bull barrel rifle just used for paper punching and Pdogs. I woukdnt dare use something like that in a rifle that has to be 100% reliable in all situations like a duty or regular carry field rifle.

 

[svxwilson]

That's interesting. I was wondering if slop might even be preferable if it lets the upper vibrate a little more naturally during the shot.

The most accurate ARs don't have any slop. A good shooter with consistent technique can make a sloppy receiver set shoot well but that is just because they are consistent not the rifle. IMO.

For example, JP factory receiver sets feel like 1 piece until you remove the take down pins. JP custom chooses the right pin for the receiver set and or sand .00x" off of the pin to get it to fit tight.

The only downside to tight receiver fit with the oversized pins is it may require using a light couple taps from a hammer (or a rock) and something to drive the pin out until they get some mileage. I use a golf tee that stays in my range bag. After a few thousand rounds and removing them for maintenance they loosen up so they are not so tight.

 

[celltech]

The set screws work fine to remove most of the slop. It's a fine line between removing all of it and leaving enough so you can even push the pins out again. On receivers that don't have the screw I have stuck a piece of gaffers tape on the bottom receiver ledge and it takes up the play as well.

 

[RUTGERS95]

slop is part of the original design, nothing wrong with slop

 

[RUTGERS95]

The most accurate ARs don't have any slop. A good shooter with consistent technique can make a sloppy receiver set shoot well but that is just because they are consistent not the rifle.

For example, JP factory receiver sets feel like 1 piece until you remove the take down pins. JP custom chooses the right pin for the receiver set and or sand .00x" off of the pin to get it to fit tight.

The only downside to tight receiver fit with the oversized pins is it may require using a light couple taps from a hammer (or a rock) and something to drive the pin out until they get some mileage. I use a golf tee that stays in my range bag. After a few thousand rounds and removing them for maintenance they loosen up so they are not so tight.

wholly inaccurate as slop has zero to do with accuracy. Machining to tight tolerances and machining for accuracy often go hand in hand however, they are not codependent. Have had plenty of sub MOA shooters with slop and plenty with none.