Is there anyone sleeving AR uppers?
If your talking about what I think you are my answer is NO because it is a waste of time or NO because I wouldn’t miss match a receiver set. This guess the question game is fun.
OP - please be more specific/explanatory in your question.
What is “sleeving”?
Sleeving, for an AR, would be boring out the upper to fit a (for example) stainless steel sleeve that would contain the BCG, as well as provide a stiffer and stronger barrel attachment.
Sorry. I thought sleeving would be self explanatory.
I have a billet upper I’m getting ready to sleeve and didnt see anyone else doing so on the 'net so I thought I’d ask here.
GH41 - generally, for precision rifles. More rigidity is considered a good thing. Not sure what you were thinking about with the mismatching bit.
This would allow a precisely fit bbl, extension, and nut that would support heavier varmint barrels more effectively.
i actually thought you were referring to the sleeving of barrels to ‘renew’ worn out rifling in fixed barrels on old guns. but since the AR barrel is easily replaced, that didn’t make sense.
since what you’re suggesting with an AR isn’t common practice, it wasn’t obvious (to me).
question - why sleeve vs. making the upper out of steel? i’m assuming weight isn’t a concern here, and i’d probably want the receiver to be made of a single material since the optic and barrel will be mounted to it. i wouldn’t want a steel-aluminum interface in-between the optic and barrel as i’m not sure what the differences in thermal expansion might do (just my gut feel).
Agreed on the single material upper. And unless I was running a very long and heavy profiled barrel, I wouldn’t bother with either. A MUR upper should provide plenty of extra rigidity…
A forged upper is generally stiffer than a billet. A forged MUR upper is stiffer still. In one sub-forum, there is a sticky about upper receiver flex.
An upper sleeved with a stainless steel tube would be much lighter than an all steel upper. If the upper is machined so the sleeve is an interference fit, there won’t be any problems with it coming loose due to thermal expansion and the OD of the tube will grow larger and the ID of the upper will shrink with heat
Looking at a specific benchrest game that doesnt allow steel uppers or lowers.
Thanks for the responses.
I did a special run of uppers for Saddam with titanium. Apparently they weren’t game changers.
A quality upper that has been faced and has the barrel bedded will produce astonishing results.
Says who? You? A properly machined upper doesn’t need facing and gluing a barrel into the upper does nothing more than make it harder to remove! Astonishing my ass.
Can you expand on this? Given the same alloy, say 7075, and same final dimensions between a forged and a billet upper, what makes the forged example stiffer/stronger?
I’ve been trying to wrap my head around this as I’ve seen a few here post the same. I’m just not seeing it unless I don’t understand how a forged upper is made.
Density and flow of grain seem to be most common discussion points between forging and billet.
I thought forgings were stiffer due to the stresses, but billet was more precise(or maybe uniform) and usually thicker for added rigidity. Is this wrong? I’d like to know so I can explain if asked and actually have an idea of what I’m talking about.
Forged receivers are usually stiffer, ounce for ounce. This is due to the metal grain of the forging following the shape of the part. The grain of the billet is just straight & parallel.
The simpler shape of the billet block makes it easier to index to the machine tool before machining and is easier to make jigs for mass production.
Billet receivers are made thicker and heavier to achieve the same stiffness as a forged receiver
The forged VLTOR MUR is designed to be stiffer than a standard forged upper and is only about an ounce or so heavier
Usually, billet receivers are heavier because forged receivers have thinner and more constant web sections and tend to follow the internal contours more closely, thus has less excess material. Billets are limited by how much time they feel like spending machining, they could machine an exact duplicate of a forging*, but that is time consuming…
Stiffness is based on the materials modulus of elasticity and the geometry of the part, grain structure is a very minor player in stiffness. Billet receivers are often made from 6061-T6 with a ME of 10,000 ksi, a forging from 7075 has a slightly higher ME of 10,400 ksi.
- That’s how the forging die was made, after all.
Sleeving uppers…:rolleyes:
It was a reasonable question, especially coming from a benchrest context where sleeving a receiver (but on the outside) for rigidity was once common (might still be but I wouldn’t know any more).
I had no idea this question could elicit these sort of responses.
FWIW - post forging solution treating a part will undo any grain alignment gained during the forging process. And it would need to be cold forged anyway. I don’t believe these parts are cold forged.