AR Upper?

[Jeeperator]

Yea I agree. You dont want to shoot 5.56 nato in a chamber designed for .223 rem. The pressures on the nato rounds are quite abit higher and can cause the chamber to go BOOM!. You can run both .223 and 5.56 nato in the nato chamber without issues but .223 rem wont be as accurate in the longer nato chamber. There is also the Wylde chamber which is is the happy medium between the 2 and is safe for both .223 and 5.56 nato and be more accurate at the same time. Dont forget to match the barrel with the upper reciever. If your barrel has m4 feed ramps make sure you get a upper reciever with m4 feedramps machined into it. M4 feed ramp are supposed to help the rounds feed easier under rapid fire or full auto situations but that is debatable and full auto is not legal anyway.Make sure you dont get an upper with m4 ramps and a barrel without I heard that can cause feeding problems. Remember 1:9 twist barrel work good for the lighter 55 grain bullets and 1:7 work good for the heavier 69 grain bulllets. The heavier the bullet it needs more twist to stabilize the bullet in flight ,not enough spin the bullet can tumble causing it to be very inaccurate. AK47 rounds are known to tumble, while the AKs are supposed the be extremly reliable in extreme conditions what good is it if you cant hit nothing lol. Does anybody know if a trigger job can be done by polishing the sear and disconector and not changing any of the springs. Thats how i did the 2# trigger job on the 10/22 and didnt change the springs at all. It's a dream to shoot not and almost puts the bullet in the same hole at 50 yards .

[6spdYJ]

Polishing the sear and disconnect is a good starting point for any trigger job. Changing spring s around is mostly about pull weight preference. The point of polishing is consistency. If you minimize friction, you increase the repeatability of the behavior at the moment the two separate. If you want a shorter take-up, you can (not for the inexperienced!!!) cut the disconnect down a bit. I won't say what I cut mine to, but they work well. I will say I don't recommend it, because if you go too far, you'll make an accident machine. If you know what you're doing and exactly how to do it, you can dial in a crisp, repeatable release. Not sure how effective it is with a two stage trigger though. I'm not a big fan of them, but they do add a measure of safety.
Regarding accuracy of a barrel, you can hand lap a new of old barrel to help condition the bore. I've only done it on old surplus rifles. It takes a full day to get good results, but it's way worth it.

[Lumpy Grits]

Never seen an AR type rifle labeled .223. Please show a link to such.
All I have ever seen is 5.56mm chamber markings on AR type.
Also you will never see any diff. on the target between those rounds in an AR type rifle. Match grade benchrest rifle the chambers are cut to customer specs, within SAAMI specs.
Please provide a link that shows this AK "tumble" you speak of. Mine sure doesn't "tumble".
.223 vs. 5.56mm etc.
http://en.wikipedia.org/wiki/5.56%C3%9745mm_NATO

LG

[6spdYJ]

It's not so much a tumble as a wobble. Think of it like a football being thrown. If the spin and speed match, it goes much farther and more accurately than if it's lobbed without proper spin. It's a gyroscopic effect.

[Lumpy Grits]

That is called "trajectory", that hasn't a thing to do with bullet stabilization in flight.
I understand the "football" thingy. I shoot a Sharps Rifle with black powder using a 540gn bullet out to 1K yds. It has the trajectory of a rainbow.
LG

[Jeeperator]

Thats what I meant about polishing and cutting the sear surface for a lighter crisper trigger pull. I shaved a little off the 10/22 at a time and 0check and rechecked and got it to 2#s exactly.Tested the safety slamed the butt stock on the ground and it would not fire. It is like a 2 stage now where it has the slightest take up and then it fires. I can put a small set screw in the sear and get rid of the take up and make it like a single stage but I like it the way it is. It wasnt that complicated at all I can probably assemble the trigger group blindfolded now i took it apart so many times. Lumpy click this link it give you a choice of 5.56 or .223 rem chamber and what twist rate http://www.model1sales.com/index.cfm...ategory_id=347. Its a known fact the the closer you bullet is to the rifling without touching the more accurate and tighter group will be. Hence match grade target chambers are definatly tighter and a seriouse shooter will measure the chamber and develop a load for it. I shot some custom hand loads 7.62x 51mm out of my ds arms fal and I couldnt believe the difference in accuracy and groupings compared to the surplus nato rounds.Yea it probably dont tumble at 100 yards but shoot your ak at 200-500 yards at a target and if you can hit it I bet the bullet keyholes the target. AKs and 7.62x39 variants are known for this thats why if you get hit it does alot of damage. Bullet going in sideways are devastating. If I were to shoot a 69 or 75 grain 5.56 out of my 1:9 barrel it would do the same thing but with that happening accuracy goes out the window. I think my .17 hmr has a 1:18 twist but it is only a 20 grain bullet. 10/22 is 1:16 twist with a 40 grain and so on. I wonder what a .50cal is lol?

[Lumpy Grits]

Thx for that link.
Don't agree at all about not touch'n the rifling.
Your match(Bentz chamber).22 rimfire bbls the bullet is into the rifling.
My Shilen barreled Remmy works best with 175 SMK bullets pushed .010" into the rifing. As do many others that I know.
The same goes for my BPCR rifles(Shiloh Sharps)and the hvy BP loads I fire in them.

YMMV,
LG

[Lumpy Grits]

Also, anybody can "cut" a bbl chamber. I have done many myownself. I prefere to cut my own match type chambers, just the way I am. Just lucky to have access to a full machine shop when I want it.
When I said AR and 5.56 chamber. I was talking about military issue and all of those blls are chrome lined too.
Check Colt, FN, KAC etc. Those barrels are all 5.56mm.
LG

[Lumpy Grits]

The AK 47 with the 7.62X39mm round is effective to 300-400 meters and that is was what it was built for.
http://www.diffen.com/difference/AK-47_vs_AK-74
IF your rounds tumble, then you have either a weapon or ammo issue. It was NOT built this way. Why would it be? The bullet doesn't fly "true" when that happens.
I can say that mine, nor any other AK's I have fired over the last 30+ years, have ever shown any sign of this tumble you speak of. I had little problem hit'n a steel plate at 300 yds at my local range with my 30 year old AK.
LG

[Jeeperator]

I stand corrected I thought i read somewhere 7.62 x 39mm tumbles but infact it tumbles after it enters the flesh causing devistating damage. I also just read that the 5.56 does start to tumble at far distances so who knows. My understanding is if the bullet touches the rifling it can cause extreme high pressures but I guess if your action is up for it go for it. They said you want the bullet to have a bit of jump (about .001 to .0015) before it hits the rifling. I believe my green mountian 10/22 barrel has a bents chamber but I dont think the bullet is touching the rifling even after I had the bolt head spaced but I could be wrong .I do know the longer round cci stinger wont go all the way in and they dont recomend using them with that barrel.

[Lumpy Grits]

Yes, your GM barrel's chamber is cut as a "Bentz".
The bullet tumble myth is an old urban legend. Not true, BTW.
The 5.56 round kills via hydrostatic shock due to the high speed of the bullet.
Buy put'n the bullet against the rifing, you reduce the high pressure spike that is caused buy the jump-stop movement of the bullet as it enters the rifling from the chamber's neck leade.
LG

[Tumbleweed13]

You guys ran with this. There's way more then I understand here. My lower, has a "set" screw, accessible thru the grip. This is suppose to make it tight with any upper I choose. 1 thing I've learned about rifle parts. The one you want isn't always available. I will be purchasing a stripped upper. I want the experience of building, the entire rifle. My research has brought me, to these choices. Wild. or 5,56 chamber. A chrome or nickel coated BCG. 16" mid-length gas barrel, medium profile. Twist, still unsure. Not sure if I want a flash hider, or muzzle brake. Handguard will be a full float modular unit, that will be long enough to cover the low-pro gas block, probably 11". Still try'n to figure out why some companies charge 89 bucks for an upper receiver, and others charge 189, for what everyone, says is the same thing.

[Lumpy Grits]

Go with a mil spec 5.56 chamber.
You don't need/want the upper and lower to be tight. You just want it to fit.
I have never seen the tension screw you speak of. Can you post a picture?
None of my BCGs are plated. The ONLY plating I would use, is Mil. spec hard-chrome. Same as the bore of the barrel.
Carbine gas system works very well. Don't get wrapped up about mid length.
LG

[Lumpy Grits]

Still try'n to figure out why some companies charge 89 bucks for an upper receiver, and others charge 189, for what everyone, says is the same thing.

Timex vs. Rolex.
Here is what I feel is the best made.
http://www.laruetactical.com/
I have 2 sons who have used their stuff in heavy combat, nuff said.
LG

[Tumbleweed13]

Here's a link to the lower I have. look at pics 4, and 5. In 4, you can see a 2nd hole, next to the grip screw, hole. Thats how its accessible. In pic 5, you can see the top of the set screw. Its green. Its a nylon nipple. This is adjusted, so it just touches the upper, when they are mated. Tight, was the wrong word, to use, previously. This will remove, any slop, there may be between the 2 halves.

http://www.riflegear.com/p-1190-rifl...-receiver.aspx