View Full Version : Question: National Match BCG'S & other accuracy questions..
Straight Shooter
05-19-18, 07:06
Im putting together my first build..a 20" rifle to be used for varmint/long range/hunting/target shooting/ammo testing, ect.
My research into accurizing the AR has led me to the subject of NM Bolt Carrier groups, ala Young Mfg & a couple others.
After finding out the physical differences between a standard bcg & a NM...Ive listened to some rather sound reasoning on why they should be used to get the N'TH Degree of accuracy out of a rifle.
So, my questions are: Are any of you using these? Can you tell or see results with them? Anyone tried them with no effect? Looking for actual users..NOT opinions or guesses.
For those of you with long range rigs...what other tips/tricks or advice can you give to get the most out of a Match barrel?
Also- for pure accuracy, what is the best way to attach a gas block as to not impede with barrel harmonics? And what muzzle devices should be considered on a long range gun?
HelloLarry
05-19-18, 09:50
So, my questions are: Are any of you using these? Can you tell or see results with them? Anyone tried them with no effect? Looking for actual users..NOT opinions or guesses.
I shoot a lot of HP, including the Nationals and I am not aware of anyone using a "NM carrier". 'm sure they are out there, just nobody has made a point of mentioning it at a match or on any HP forums.
For those of you with long range rigs...what other tips/tricks or advice can you give to get the most out of a Match barrel?
Also- for pure accuracy, what is the best way to attach a gas block as to not impede with barrel harmonics? And what muzzle devices should be considered on a long range gun?Have the barrel chambered with a specific bolt. Barring that, make sure the bolt you do have is not set up for a carbine. The extra force extractor doesn't help accuracy, according to Bob Whitley.
Gas block attachment - The accepted way to attach sight towers is with set screws & LokTite. However, I have seen a lot of clamp on gas blocks. I'd do whatever Whitley, White or Holliger does.
The only muzzle device I'd consider is a bare muzzle.
On an HP forum, I asked about NM carriers and was told they did nothing either way for precision.
I didn't know those things were still marketed. That's some OLD SCHOOL stuff there.
"National Match" ANYTHING for the M16 is horseshit and marketing. There's a sucker born every minute, and many think it's a sin for them to keep their money.
The last United States Army National Match drawings and technical specifications were drawn up for the M1911A1, M1, and M14, and their respective cartridges. The USAMU specs out their own stuff for internal consumption by the Army, Army Reserve, and Army National Guard teams, as well as for requesting state National Guard teams. There are no formally published military National Match specs for the M16 and M9 pistol, yet the service teams shoot them at Camp Perry.
The Marines spec their own stuff, as do the Navy and Air Force.
Ned Christiansen
05-19-18, 11:50
To me taking out carrier slop made too much sense to not try it, so I welded a ring around the carrier tail, ground it to, I don't remember but probably .997, put some flats on it, and ran it in my HP target gun. The carrier tail is otherwise about .070 smaller than the hole it runs in. This was probably early 90's. I did it knowing that it might compromise reliability but it sure never did. It pretty much triples the effective length of bearing surface taking out a lot of wobble. I also modified a buffer to help keep the carrier tail centered.
All the minutia that most people consider "necessary" to make a 1911 or Remington 700 more accurate, it surprises me that there has not been a big deal made about doing this.
Did either mod help? Honestly I didn't do comparative testing so I don't know, but I do know they didn't hurt. At least in theory, one or both mods "have to" help but if target competitors that are way more into it than I ever was don't do it, I have to wonder if there's any benefit..... but also, I ask, did they ever try it.
It doesn't hurt. Can't honestly say if it helps.
http://i65.tinypic.com/av0vt1.jpg
only thing I do on precision builds is get the bolt headspaced to the barrel. CLE offers this. JP offers this. I am sure others offer it as well.
I use 2 carriers: USGI phosphate or JP Low mass if I am using an adjustable gas system.
I use red loc-tite(loctite 660 retaining compound might be a "better" choice though) around the barrel extension and under the gas block to act as a sort of "shim" to take up any inconsistencies.
Besides that, using a high quality barrel(cut rifle is my preferred), and a decent free float tube and a NICE trigger is where its at.
Working up a load for your setup is probably where more accuracy can be gained than all the tricks in the book, at least on the AR platform.
Straight Shooter
05-19-18, 13:58
It doesn't hurt. Can't honestly say if it helps.
http://i65.tinypic.com/av0vt1.jpg
sinister- what carrier is that?
Gents- all info & answers here are awesome, thank you so much. I do agree reloading would be a huge benefit- but I dont reload, so Im gonna try to build up as accurate a rig as I can afford. Also agree on getting a matched bolt, which I will do.
HelloLarry- Thanks for advice on the extractor spring & gas blocks.
Please keep any more info coming.
titsonritz
05-19-18, 14:08
The only muzzle device I'd consider is a bare muzzle.
Would you consider a threaded barrel with a thread protector?
Straight Shooter
05-19-18, 14:20
Would you consider a threaded barrel with a thread protector?
Wondering the same thing.
I think the carrier's a Toolcraft.
USAMU M16s are all threaded for flash suppressor/ A2-A4 compensators. They don't harm anything if done right and true and act like a crown protector.
Don't put your muzzle device on too tight or it will open your groups.
If you don't handload you'd better buy quality match ammo.
just as a point of reference...
My precision 5.56 build(CLE spun Krieger barrel) has an AAC 51T brake on it... Gun shoots 1/2 to 3/4 moa with my tuned loads... Maybe that doesnt win big name competitions, but for me its great.
My 6.5creed AR with a JP barrel has an AAC 51T brake on it as well... smacks 6" gongs at 900 yards(if I am able to read the wind right)....
IMO a good muzzle device shouldnt affect bullet flight...
Straight Shooter
05-19-18, 14:56
I think the carrier's a Toolcraft.
USAMU M16s are all threaded for flash suppressor/ A2-A4 compensators. They don't harm anything if done right and true and act like a crown protector.
Don't put your muzzle device on too tight or it will open your groups.
If you don't handload you'd better buy quality match ammo.
Thank you brother.
Straight Shooter
05-19-18, 14:57
just as a point of reference...
My precision 5.56 build(CLE spun Krieger barrel) has an AAC 51T brake on it... Gun shoots 1/2 to 3/4 moa with my tuned loads... Maybe that doesnt win big name competitions, but for me its great.
My 6.5creed AR with a JP barrel has an AAC 51T brake on it as well... smacks 6" gongs at 900 yards(if I am able to read the wind right)....
IMO a good muzzle device shouldnt affect bullet flight...
Hell yes, that would be good enough for me too!
Would you consider a threaded barrel with a thread protector?
During the Clinton Administration ban some of us learned that the lack of muzzle device improved accuracy on a match rifle. I would not consider a threaded barrel on a match rifle. I would on a multi-use rifle that may have a muzzle brake or flash hider installed at some point.
As far as a "match carrier" is concerned, I would not bother. I would want the bolt headspaced to the barrel with consistent contact between bearing surfaces.
Straight Shooter
05-19-18, 20:00
During the Clinton Administration ban some of us learned that the lack of muzzle device improved accuracy on a match rifle. I would not consider a threaded barrel on a match rifle. I would on a multi-use rifle that may have a muzzle brake or flash hider installed at some point.
As far as a "match carrier" is concerned, I would not bother. I would want the bolt headspaced to the barrel with consistent contact between bearing surfaces.
Sound advice, and I appreciate it sir.
HelloLarry
05-20-18, 08:47
Would you consider a threaded barrel with a thread protector?
Yes, I would. As others have pointed out, over tightening is counterproductive. So avoid that.
But, the AMU shoots with A1 or A2 birdcages while acknowledging that they give up some degree of accuracy in doing so. IIRC, it's on the order of about 1/3 MOA.
And that just points out another reason why you don't see much honing of the equipment to get it to shoot better - position sling shooting is more about skill than accuracy and the platform is already more than accurate enough with just some basic tweeks. Barrel, trigger, sights & float tube/rail and you too can be a National Champion. I love it.
HelloLarry
05-20-18, 08:53
IMO a good muzzle device shouldnt affect bullet flight...
I would not argue with you on that.
But the A1/A2 does and there isn't anything else that's allowed in HP rules.
Ned Christiansen
05-20-18, 09:27
If cost is no object, there's no need to handload these days-- there are so many great factory loads available. I have not tried them all but getting under 1 MOA is no struggle and a bunch of them will do 1/2 MOA.... I wish I had time to do a comparo shoot using my rear-banded carrier. Maybe later this summer.
Straight Shooter
05-20-18, 12:32
If cost is no object, there's no need to handload these days-- there are so many great factory loads available. I have not tried them all but getting under 1 MOA is no struggle and a bunch of them will do 1/2 MOA.... I wish I had time to do a comparo shoot using my rear-banded carrier. Maybe later this summer.
Id be interested in your favorite factory loads, if you care to divulge them..also, who makes a rear-banded carrier? I cannot find them.
Google "Anti-tilt bolt carrier"
titsonritz
05-20-18, 13:37
How about a slightly different approach?
https://www.brownells.com/rifle-parts/receiver-parts/buffer-tube-parts/buffer-tubes/ar-15-m16-anti-tilt-mil-spec-buffer-tube-prod64568.aspx
Straight Shooter
05-20-18, 14:15
Google "Anti-tilt bolt carrier"
Thanks...been using the wrong terminology.
Straight Shooter
05-20-18, 14:16
How about a slightly different approach?
https://www.brownells.com/rifle-parts/receiver-parts/buffer-tube-parts/buffer-tubes/ar-15-m16-anti-tilt-mil-spec-buffer-tube-prod64568.aspx
Wow..never saw that before.
Ned Christiansen
05-20-18, 22:17
Black Hills 77's-- just over half an inch (Blue Box). Nosler 69's and 77's, same. Federal GMM deserves its rep too for accuracy. My two most accurate barrels are a Wilson Combat Super Sniper 20" and an Adams Arms Voodoo which surprisingly is a standard Gov't profile barrel.... but wow it shoots!
Almost anything with 77 Sierra Match Kings will hover around or under an inch-- the IMI, the CBC for example. Hornady loads 75 BTHP's thee ways including a "match" version but for me the most accurate has been the 5.56 version (the others are .223 pressure).
vicious_cb
05-21-18, 01:30
Putting "national match" in front of something is akin to putting "tactical" in front of a product name. It doesnt mean shit.
Straight Shooter
05-21-18, 04:42
Putting "national match" in front of something is akin to putting "tactical" in front of a product name. It doesnt mean shit.
I tend to agree fully. The noted differences on the Young Mfg bcg were a 30% increase in the contact surfaces of the carrier, along with being 1 ounce heavier for dwell time.
"Supposed" to keep bolt in more perfect alignment during lock-up. Thats what THEY say...and why I asked here for expert advice.
After reading and studying this issue for a few weeks now, Ive come to believe that, yes, it PROBABLY makes some difference..but getting a bolt matched up to a barrel will probably achieve as much or greater results, so thats where Im headed right now, pending further incoming info.
Straight Shooter
05-21-18, 04:46
Black Hills 77's-- just over half an inch (Blue Box). Nosler 69's and 77's, same. Federal GMM deserves its rep too for accuracy. My two most accurate barrels are a Wilson Combat Super Sniper 20" and an Adams Arms Voodoo which surprisingly is a standard Gov't profile barrel.... but wow it shoots!
Almost anything with 77 Sierra Match Kings will hover around or under an inch-- the IMI, the CBC for example. Hornady loads 75 BTHP's thee ways including a "match" version but for me the most accurate has been the 5.56 version (the others are .223 pressure).
I really appreciate that info sir, awesome of you to give it out. Some dudes guard that info like the family jewels!
Google "Anti-tilt bolt carrier"
I haven't tinkered with the Anti-tilt bolt carriers and haven't heard them discussed at rifle matches. Do you notice a difference in accuracy?
Not sure how or why an anti-tilt carrier would increase accuracy or help anything in a DI gun. A piston AR is another story.
The bullet has left the bore before the carrier begins it's rearward movement, correct? I believe this to be true with most common AR-15 barrel lengths/gas system lengths. Not so sure about 26'' space guns.
Also, there is inherently some wiggle between the bolt and bolt carrier. Slight. So even if the carrier had zero tilt and rode on linear bearing rails, the bolt itself could tilt ever so slightly whichever way it wants to. The ejector's/extractor's pressure on a chambered cartridge might pre-load(tilt) the bolt to some extent too. I guess this could be effected by cartridge headspace.
Finally, let's say the carrier is moving rearward just before the bullet has left the muzzle, a mm or two, wouldn't the tilt be the same each time and therefore not hurt accuracy?
titsonritz
05-21-18, 12:53
https://www.youtube.com/watch?v=P2-BIENNPOg
Straight Shooter
05-21-18, 13:02
https://www.youtube.com/watch?v=P2-BIENNPOg
You see? When I see guys like this who freaking EXPERTS putting validity to NM bcg's..theres GOT to be some kinda worth..or no one would bother making them.
LMT Shooter
05-21-18, 13:35
You see? When I see guys like this who freaking EXPERTS putting validity to NM bcg's..theres GOT to be some kinda worth..or no one would bother making them.
Not to be sarcastic, but the same is said about barrel break-in, and there is no consensus on that, at all. Some swear by it, while others swear at it.
I'm curious as to what kind of wear (If any?) those screws he put in add to the rifle.
You see? When I see guys like this who freaking EXPERTS putting validity to NM bcg's..theres GOT to be some kinda worth..or no one would bother making them.
Given the experience of the man in the video, I will give his opinion weight. I have had several match rifles that would easily shoot 1-1/2" groups at 300 yards off the bench without addressing the issue of bolt carrier tilt.
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