You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
Colt 6721 HBAR upper and Daniel Defense lower
- Thread starter Tool
- Start date
LeverGunFan
New member
I recall that the take down pins are the same for Colt, it's the trigger pins that can be a different size.
how loose is "too loose to be accessible" , i assume you mean acceptable. Most rifles have more play than most people realize, even from factory built rifles. Bet it shoots and runs just fine.
if you want a tighter fit might I suggest the Accu-wedge.
https://www.midwayusa.com/product/100340833?pid=518277
if you want a tighter fit might I suggest the Accu-wedge.
https://www.midwayusa.com/product/100340833?pid=518277
Last edited:
I don't like the wedge. You want to pull the receivers together, instead of wedging them apart just to feel better. Compression pin is one option. My favorite is glass bedding the upper to the lower with epoxy putty, such as JB weld. I have also tried shimming with copper / stainless steel tapes. It worked ok. Bedding is better.
-TL
Sent from my SM-N960U using Tapatalk
-TL
Sent from my SM-N960U using Tapatalk
I'll ask it again since it wasn't answered before: How loose is TOO loose to be acceptable? I say this because I have an old(er) Armalite National Match rifle that is impressively rattly between the upper and lower. You can see plenty of daylight with it assembled. It's taken me to many match wins and top placings, been through 3 barrels and would probably shoot MOA at 600 yards from a rest with optics. The receivers still wobble a little when assembled and I'd guess it never mattered that they do.
Remember, your sighting system and barrel are all attached to the upper together. Even with a little play between the receivers, it'll shoot to the same point as long as you're applying pressure to the buttstock and forend the same way each time. Since you're talking about mating a Colt upper to a DD lower, I'm assuming you're not chasing .5 MOA accuracy. In which case, the wobble won't matter. Repeat that 2 or 3 more times if you're shooting generic 55 or 62 grain FMJ 5.56 ammo, which is mostly 2-3 MOA ammo.
Remember, your sighting system and barrel are all attached to the upper together. Even with a little play between the receivers, it'll shoot to the same point as long as you're applying pressure to the buttstock and forend the same way each time. Since you're talking about mating a Colt upper to a DD lower, I'm assuming you're not chasing .5 MOA accuracy. In which case, the wobble won't matter. Repeat that 2 or 3 more times if you're shooting generic 55 or 62 grain FMJ 5.56 ammo, which is mostly 2-3 MOA ammo.
LeverGunFan
New member
Here are a couple of options to tighten up the fit between the lower and the upper:
Oversize pins, from JP Rifles, available as .001 inch oversize from standard.
Expanding pins from Barnes Precision Machine
Oversize pins, from JP Rifles, available as .001 inch oversize from standard.
Expanding pins from Barnes Precision Machine
1 moa at 600yd is very tall order, especially for 5.56 gas gun. I wouldn't change a thing.
For us who is still chasing that dream, every small bit counts. I think the op should shoot the rifle first, before deciding what to do next. Maybe he doesn't need change anything either.
Conventional rifles, say Remington 700, almost always benefit from good bedding of the action in the stock. They have sight/optics on the action/barrel assembly too. AR should work the same.
-TL
Sent from my SM-N960U using Tapatalk
For us who is still chasing that dream, every small bit counts. I think the op should shoot the rifle first, before deciding what to do next. Maybe he doesn't need change anything either.
Conventional rifles, say Remington 700, almost always benefit from good bedding of the action in the stock. They have sight/optics on the action/barrel assembly too. AR should work the same.
-TL
Sent from my SM-N960U using Tapatalk
jetinteriorguy
New member
This is one of the things I like about Aeroprecision, they have the little set screw you can adjust to eliminate any play between the upper and lower.
Glad to hear that. Do they have this set screw on all models?This is one of the things I like about Aeroprecision, they have the little set screw you can adjust to eliminate any play between the upper and lower.
Last edited:
1 moa at 600yd is very tall order, especially for 5.56 gas gun. I wouldn't change a thing.
For us who is still chasing that dream, every small bit counts. I think the op should shoot the rifle first, before deciding what to do next. Maybe he doesn't need change anything either.
Conventional rifles, say Remington 700, almost always benefit from good bedding of the action in the stock. They have sight/optics on the action/barrel assembly too. AR should work the same.
-TL
Sent from my SM-N960U using Tapatalk
But ARs don't necessarily need the tricks conventional rifles require either. There are questions of whether things like lapping the barrel/receiver fit or matched receivers are beneficial on an AR versus standard fit parts. A good barrel with matched bolt, free-floated and shooting quality ammo is at least 95% of the equation.
Also agreed, the OP needs to shoot his rifle first and decide if it needs anything. And again, if he's only planning to shoot M193 or M855 type ammo, doing anything to the rifle fit to chase potential fractions of group improvement is fruitless. He should determine his planned uses and let that dictate where to go with the rifle. My MOA-capable heavy barrel match rifle isn't going to replace my 16" lightweight carbine for quick, close range work, just as the lightweight carbine isn't the rifle I'd pick for shooting 20-round groups past 200 yards. Horses for courses and all that.
The set screw is better than the wedge, but it is still pushing the upper and the lower apart.This is one of the things I like about Aeroprecision, they have the little set screw you can adjust to eliminate any play between the upper and lower.
Over sized pins works to a point. Expanding pin (compression pin) works great, except that they are expensive and slow to field strip. There are much affordable home made alternatives on eBay.
-TL
Sent from my SM-N960U using Tapatalk
jetinteriorguy
New member
I’m not sure but would assume it’s a standard feature. Funny thing, mines a full Aeroprecision rifle and the fit was pretty much perfect and didn’t really need this feature, so I’m guessing it’s included to help with mismatched builds possibly.Glad to hear that. Do they have this set screw on all models?
People also believe the tight fit doesn't do anything. But others pay extra for a matched pair.I think Colt is the blame. I put that Colt upper on an Aero Precision and see the same amount of sloppiness.
On the other hand, my Daniel Defense upper fits perfectly on both lowers. Why do people think DD is overrated? Their OEM stock also has a very tight fit.
The original Stoner's design didn't have pins. The upper mated with the lower on sliding rails, just auto pistol slide on its frame. It could do better, but more expensive to make and harder to service in the field. On the government's request it was converted to pins.
Shoot the rifle and see how it goes. Maybe it is good enough.
Sent from my SM-N960U using Tapatalk
jetinteriorguy
New member
Just adjust the nylon tipped set screw in the Aeroprecision lower until the slop is gone, but don’t overdo it or you’ll have trouble getting things to go back together easily.I think Colt is the blame. I put that Colt upper on an Aero Precision and see the same amount of sloppiness.
On the other hand, my Daniel Defense upper fits perfectly on both lowers. Why do people think DD is overrated? Their OEM stock also has a very tight fit.