Looking for information on upper/lower wobble.

[Lefty223]

A quote on upper to lower receive fit: "You can get them too tight, but you can't get them too loose to shoot well", Bill Wylde. Source: The Competitive AR15, Glen Zediker, Page 56. Bill Wylde is an expert on Service Rifles, barrel design, etc. He's fired some incredibly small groups with the AR15.

Ahhh, beat me to it! As I knew Zediker's book had a comment about this.

What makes it work, or less to zero problems on the AR platform is primarily the linear design of the AR action. That makes it inherently accurate. To that end, the Stoner design is ingenious!

FWIW on more traditionally designed firearms, especially those using 2 piece stocks, poor fit and/or bedding between the receiver to buttstock, or even to the forend, can lead to wicked accuracy inconsistencies and nature to 'throw' errant shots.

[tom12.7]

For most, the lash or play means little, as preload either by the action spring solely or by that with a combination of external forces. Preloading with a sling/ bipod/ support hand tensions or extensions/ etc.. are examples of external forces. For most, that removes issues as long as consistent preloads are used for the uses.
There are many ways to work this well in most all 5.56 AR systems. If you look into 7.62 NATO AR systems, some of the above preloads don't work as well as some others. One of the good things though is that using 7.62 NATO AR system techniques can apply well in the 5.56 systems. That can make some things simpler for some.
This could be discussed further for some if wanted.

[Mysteryman]

A quote on upper to lower receive fit: "You can get them too tight, but you can't get them too loose to shoot well", Bill Wylde. Source: The Competitive AR15, Glen Zediker, Page 56. Bill Wylde is an expert on Service Rifles, barrel design, etc. He's fired some incredibly small groups with the AR15.

Thank you sir, this is the kind of stuff I'm after.

MM

[Glock9mm1990]

People don't mention this but the upper and lower play is only noticeable when the rifle is empty. Once you seat a loaded 30 round mag, then the play is mostly eliminated and once you then chamber a round the loose play is gone outright. At least thats how it is for 3 out of 4 of my ARs, my other one is the only one to have a tight fit with no wobble.

[ajyaros]

Shims

[Mysteryman]

People don't mention this but the upper and lower play is only noticeable when the rifle is empty. Once you seat a loaded 30 round mag, then the play is mostly eliminated and once you then chamber a round the loose play is gone outright. At least thats how it is for 3 out of 4 of my ARs, my other one is the only one to have a tight fit with no wobble.

That's a good point, thanks.

Shims

I'm aware of the stupid things people do to solve the non existent issue I am concerned with facts or hard data that illustrates why worrying about the play/wobble is a waste of time.

MM

[brodband]

A little wobble never hurt anyone. I hated having uppers and lowers that were so tight you had to use a bullet tip to punch the pins out of.

[Mysteryman]

A little wobble never hurt anyone. I hated having uppers and lowers that were so tight you had to use a bullet tip to punch the pins out of.

Again, I'm aware of the waste of time it is to worry about the wobble. I am not worried about the wobble. I am simply trying to find hard sources from folks who spent the time and effort to prove that the wobble is of no concern.

MM

[BlueCorn]

I prefer a snug fit but have several that wobble. I may be wrong but I thought I had read that there was a spec for the fit of the upper and lower. For some reason I'm thinking the spec was anything over 20 thousandths was out of spec.

[Doc Safari]

OP: The gas tube is generally loose-fitting in the upper receiver and you may be able to rattle it with your fingers when the bolt is retracted. Just so you don't run out of things to needlessly worry about.