Matched bolt and barrel.......Important?

[lh leggtowner]

Ok, so I have just got done with my second AR build. Not a lot spent but, built the way I want them. They look great and shoot pretty good if I do my part. I am still new to this but, I want to or like to build a super accurate long range AR now. It gets confusing with all the companies selling stuff related to this project so, I thought I would ask you all some questions.

1st) How important is it to have a "matched bolt and barrel"? I see that Lothar Walther sells a set. Probably others if you know any let me know.
2nd) Does anyone sell "trued" uppers? I see that I can do it myself with a tool. But machined seems (maybe) like it would be better.
3rd) It is going to be a 224 Valkyrie. Should I get a 6.5 twist or, will a 7 do? 80-90 grainers will be the primary pills down the tube.

Any other information that you all can guide me to would be a GREAT help. I have a ton of questions on this subject but, this should get me started for now.

 

[Wheres-Waldo]

A matched bolt/barrel gives you a few things, depending on the MFG.

It should ALWAYS ensure your headspace is at minimum.

In a Krieger AR10 & others, it will ensure even & complete lug contact.

It can also provide less slop in lug clearance (the distance from the end of the barrel shank to the extension lugs).

You can lapp or have a receiver lapped, not a big operation when using a mandrel.

You can also lap bolt lugs to extension lugs if needed, without too much ass-pain, though most quality bolts should have good contact... just check it with some Dykem.

 

[308pirate]

Coming from an NRA/CMP highpower background, I've seen too many ARs (including every NM rifle I owned) to be capable of 3/4 MOA performance or better at 600 yards without resorting to matched/lapped bolts and extensions.

Some people can't stop until they do everything possible no matter if some of what they do makes no difference. Some people focus on the things that have the most impact and don't waste time/money on those that are marginal.

 

[padom]

I always have my bolt headspaced to my AR barrels but I dont generally buy off the shelf barrels so its as easy as dropping off or shipping my bolt to the smith which he headspaces to the barrel when spinning it up and ships it back. WOA, CLE, Keystone, PVA all do this and request the bolt when having a custom barrel spun up.

I have never "trued" or "lapped" a upper in the 100's of AR's Ive built. Buy a good upper/lower set and your good to go. Not sure what barrel length your going for but a good, beefy, heavy billet upper will benefit a longer/heavier precision AR barrel. (MEGA SBU, Seekins IRMT-3, etc) I personally have been stocking up on these MEGA SBU billet uppers at this crazy price. They are extremely beefy which you notice the moment you pick one up.

http://www.jsesurplus.com/AR-15SBUBilletUpperwithoutSideChargingHandleSlotJSEEXCLUSIVE.aspx


Matched with this billet lower and you have a super tight fitting, rock solid receiver set with no play.

http://www.jsesurplus.com/megaarms-4-1-1.aspx

 

[spife7980]

Ive been checking the headspace on my bolts and barrels. I always assumed thats what they were advertising doing, making sure the two parts headspaced when they said that. But they are actually making sure each individual lug has full contact in addition to headspace?

 

[Niles Coyote]

@padom just curious what handguards you use with your SBU's?

 

[padom]

@padom just curious what handguards you use with your SBU's?

The two Im using right now on a 20" Kreiger .223 heavy barrel and 24" Kreiger 220 Thunderbolt heavy barrel are:

Seekins SP3R MLOK 15"
YHM 15" TJ Competition Series


Both of these handguard are very rigid and secure nicely. They also provided a large ID so there is plenty of clearance around my adjustable gas blocks, one being a .936.

 

[Niles Coyote]

The two Im using right now on a 20" Kreiger .223 heavy barrel and 24" Kreiger 220 Thunderbolt heavy barrel are:

Seekins SP3R MLOK 15"
YHM 15" TJ Competition Series


Both of these handguard are very rigid and secure nicely. They also provided a large ID so there is plenty of clearance around my adjustable gas blocks, one being a .936.

Thanks for that info, I did some light grinding on a cheep handgard that was big enough to fit over my .936 SLR adjustable gas block. Its good to know the SP3R will work too.

 

[padom]

Thanks for that info, I did some light grinding on a cheep handgard that was big enough to fit over my .936 SLR adjustable gas block. Its goog to know the SP3R will work too.

SP3R is hands down one of my all around favorite AR15 handguards. Primary Arms has them on sale every few months for $99.99 which is a steal for such a nice handguard. I love my SLR's and Geissele but they just dont provide the clearance I want around an adjustable gas block on a precision rig.

Im also a huge fan of the Daniel Defense MFR handguards but they are expensive. They clear my adjustable gas blocks as well, love their mounting system and are very solid.

 

[lh leggtowner]

I always have my bolt headspaced to my AR barrels but I dont generally buy off the shelf barrels so its as easy as dropping off or shipping my bolt to the smith which he headspaces to the barrel when spinning it up and ships it back. WOA, CLE, Keystone, PVA all do this and request the bolt when having a custom barrel spun up.

I have never "trued" or "lapped" a upper in the 100's of AR's Ive built. Buy a good upper/lower set and your good to go. Not sure what barrel length your going for but a good, beefy, heavy billet upper will benefit a longer/heavier precision AR barrel. (MEGA SBU, Seekins IRMT-3, etc) I personally have been stocking up on these MEGA SBU billet uppers at this crazy price. They are extremely beefy which you notice the moment you pick one up.

http://www.jsesurplus.com/AR-15SBUBilletUpperwithoutSideChargingHandleSlotJSEEXCLUSIVE.aspx


Matched with this billet lower and you have a super tight fitting, rock solid receiver set with no play.

http://www.jsesurplus.com/megaarms-4-1-1.aspx

Wow great information. I will check them out.

 

[lh leggtowner]

@padom just curious what handguards you use with your SBU's?

The ones I done were a yhm free float 4 way rail one. The other one I done was a m lock from psa.

 

[flyer]

Beside headspace, there is no other way bolts are matched that I know of.

After you start shooting, the bolt and barrel should be married so you don't get competing wear patterns which could cause the bolt to fail earlier.

 

[lh leggtowner]

Coming from an NRA/CMP highpower background, I've seen too many ARs (including every NM rifle I owned) to be capable of 3/4 MOA performance or better at 600 yards without resorting to matched/lapped bolts and extensions.

Some people can't stop until they do everything possible no matter if some of what they do makes no difference. Some people focus on the things that have the most impact and don't waste time/money on those that are marginal.

What components do you generally run. Barrels and whatnot.

 

[lh leggtowner]

Seen a heavier barrel from Bison Armory that seemed like a great buy. No bolt.

Also seen where lothar was selling a matched set of barrel and bolt. Looked good.

What about these guys? What y’all think.
Remember it is going to be a Valkyrie.

 

[flyer]

Oh, the best 6.8 SPC/.224 Valkyrie bolt is the ARP super bolt.

ARP will match one of their bolts to one of their barrels if you buy from them.

I think they will have a new batch of .224 barrels made with a SAAMI spec reamer pretty soon.

I was looking at .224 but went with TAC 6 instead, no twist issues, much better bullet selection and more efficient.

Federal is rumored to be working on a 6 Valkyrie and has the TAC 6 chamber specs so there might be something very similar with a SAAMI spec and factory ammo pretty soon.

 

[pugnado]

Most places will sell a properly headspaced bolt to go with their barrels. I'm pretty sure they just pluck a barrel out of their pile and then start picking random bolts and stop when they find a combination that fits good enough. Probably use a gauge compliant with SAAMI specs etc...

It's probably more important with wildcat cartridges and barrels than it is milspec stuff.

For my AR-10 6.5 Creedmoor build, I spent $60 on a pair of go / no-go headspace gauges because I bought the bolt ($220) and barrel ($840) separately and felt that it was good insurance / test before ruining it all on the first round.

 

[Forgetful Coyote]

Oh, the best 6.8 SPC/.224 Valkyrie bolt is the ARP super bolt.

ARP will match one of their bolts to one of their barrels if you buy from them.

I think they will have a new batch of .224 barrels made with a SAAMI spec reamer pretty soon.

I was looking at .224 but went with TAC 6 instead, no twist issues, much better bullet selection and more efficient.

Federal is rumored to be working on a 6 Valkyrie and has the TAC 6 chamber specs so there might be something very similar with a SAAMI spec and factory ammo pretty soon.

ARP always came off as a "budget" brand to me but the 6.8 shooters swear by them.. you ever used their barrels?

 

[flyer]

Yes, I have three, they were expensive compared to some of the budget stuff out there but they work well and H stands behind them.

It's a pretty small opperation and H is making it smaller with a move to the Florida Keys I think.

When I bought cost wasn't the #1 consideration, he was just making stuff that no one else was.

 

[spaniel]

It's peace of mind to know that the headspace has been checked.

Lots of people assume that they don't have to check headspace when they build ARs. One of them had a case rupture from excessive headspace on my range doing that while I was standing next to him. Kinda wish he'd told me what he had done when he touched that round off, I'd have been standing a lot further away....

 

[lh leggtowner]

ARP always came off as a "budget" brand to me but the 6.8 shooters swear by them.. you ever used their barrels?

I already have a arp bolt with a black stone 6.8 upper. This is an awesome rifle. Shoots great. 6.8 guys do swear by it.

 

[308pirate]

What components do you generally run. Barrels and whatnot.

Typically Wilson, Pac-Nor, or WOA stainless. Whatever bolt was with the rifle when new.

 

[whatsupdoc]

How many AR15 bolt barrel combinations have you guys heard failing headspace?

 

[flyer]

Quite a few Grendles because it uses an oddball bolt face recess.

 

[Waorani]

Headspace gauges are cheap so why not check just for your own peace of mind. Ironically, the only AR15 headspace fails I've seen were a couple of Fail Zero bolts when they first came out.

 

[lh leggtowner]

I hear people saying "Wilson" for their barrels. Is that Wilson combat or Wilson Arms. I got to digging into it and there are actually two different places. Or, websites anyways.

 

[308pirate]

Wilson Arms. The three that I've used shoot better than the barrel snobs (and I am one) care to admit.

 

[padom]

Wilson Arrms barrels straight up shoot. I have many

 

[flyer]

Wilson Combat makes a good barrel too.

 

[lh leggtowner]

Ok craziest question yet...... where and what brand gas tubes do y’all use.

 

[308pirate]

Ok craziest question yet...... where and what brand gas tubes do y’all use.

It doesn't matter.

Just make sure it's not binding as it goes into the bolt carrier key.

 

[flyer]

The sleaziest gas tube you can find is probably still $10 and many reputable brand names are less than $20 so I spend a few bucks to get a brand name, which one doesn't seem to matter much.

I like the nitrided tubes for aesthetics.

 

[RyanScott]

How many AR15 bolt barrel combinations have you guys heard failing headspace?

A major AR shop I used to work for headspaced every bolt/barrel combo they sold, whether they were house branded barrels or third party. 1/10 failed headspace due to variations in tolerances. A lot of ARs are out in the real world with the wrong headspace.