AR-15 - Looking for Top Accuracy

P

Phil3

Sergeant
Full Member
Minuteman
Dec 13, 2008
402
17
San Ramon, CA
#1
A previous post here about a month ago was very helpful on proper setup of an AR-15 for long range shooting. My objective is the same, but distance is 100, 200, and rarely, out to 600 yards (that gun range is a 4 hour round trip). I will be using a Krieger heavy barrel, 22" long, but unsure on twist and bullet weight. I also intend on using the JP adjustable gas block if that makes sense to help tune the rifle. ??? If it makes sense, I can send the upper to Krieger for barrel fitment, or I can headspace, and assemble.

My main question is on bullet weight and twist, so I can get the barrel ordered.

- Phil
 
#3
Re: AR-15 - Looking for Top Accuracy

1 in 7 or 8. 80 gr SMKs or Berger VLDs. They won't go fast but at long range SD is king. You might be happier with a 260 AR 10 or one of the 6.5 wildcats if you plan to do a lot at 300+.
My 260 DPMS LR blows away 223s if the range is long and the wind is blowing (as it always does here)

dpms260.jpg

 
#4
Re: AR-15 - Looking for Top Accuracy

Krieger offers a 1:7.7" barrel, so that seems optimal for the bullet weights you are talking about. But are those really needed if shooting MOSTLY at 100 and 200 yards? I am trying to build an AR-10, but parts are impossible to find. I was not going to go with the 260 because of barrel life, but I know from a ballistics point of view, it is superior to the .308. - Phil
 
#5
Re: AR-15 - Looking for Top Accuracy

How much do you want to spend on this? Budget usually constrains what exactly you can get for a rifle with great accuracy and features. The 1:7.7 with heavy bullets is a good way to go if you know you're going to only shoot those kind of bullets. Most of the mass producers of AR15 barrels make a 1/9 twist so that it can accomodate a larger range of bullet weights. Are you trying to make a DSM, SPR style rifle or do you want more of a target rifle that you'll shot from a bench?
 
#7
Re: AR-15 - Looking for Top Accuracy

Check junes SWAT magazine page 68. Gotta love self promotion.

1x7
Technically too tight of a twist for any .224 bullet widely available, including the 80 grain. Manufactured originally to stabilize SS109 and/or tracer ammo, but further military testing has shown other twists to be superior. Some of the very heavy custom stuff (87 grain?) may work well, but why?
1x8
Great twist for 69-80 grain bullets. Sierra once informed me that the perfect twist for their 80gr was 1x8.2xxxxx (blah blah blah big long engineers explanation followed).
1x9
Good all around twist ratio. Best suited for 52-69 grain, but either end of the envelope will be questionable

I mainly make SPR's in 1-8 twist and the 18" barrel is optimum for what i do out to 600 yards.
 
#8
Re: AR-15 - Looking for Top Accuracy

Phil,

You really need to figure out what type of shooting you will be doing the majority of the time, and set your rifle up accordingly. Many people, and I have done this myself, set up a rifle for the type of shooting they <span style="font-weight: bold"><span style="font-style: italic">think</span></span> they are going to do instead of what they are <span style="font-weight: bold"><span style="font-style: italic">actually</span></span> going to do.

Now, that's not to say you can't set up a rifle that excels at both. Personally, I am currently building a rifle to use out to 675 yards, and my predicament is similar. I shoot on a 300 yard range, and rarely get an opportunity for 300+ distances. However, there is a club less than 1.5 hours away that offers distances up to 700 yards, and there is the slight possibility I will be shooting at that distance as well. So, I am building a rifle that will get me to 700 yards. The barrel I have ordered is a stainless Lothar Walther 20" 1:8 twist, with a contour similar to the Kreiger DCM. I plan on shooting 75-77gr bullets over Varget, but I can always shoot lighter bullets for shorter distances.

Remember, you can always get by with too fast of a twist for lighter/shorter bullets, but you can rarely get by with a slower twist for heavier/longer stuff.
 
#9
Re: AR-15 - Looking for Top Accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ZLBubba</div><div class="ubbcode-body">How much do you want to spend on this? Budget usually constrains what exactly you can get for a rifle with great accuracy and features. The 1:7.7 with heavy bullets is a good way to go if you know you're going to only shoot those kind of bullets. Most of the mass producers of AR15 barrels make a 1/9 twist so that it can accomodate a larger range of bullet weights. Are you trying to make a DSM, SPR style rifle or do you want more of a target rifle that you'll shot from a bench? </div></div>

Budget is pretty open, but not unlimited. Without optics, I fully expect it to be about $2,000. Regarding bullets, I don't know what type I will be using, because I am not sure what works best for top accuracy at 100 & 200 yards, and maybe out to 600. If I have to compromise, then my bias is to the 100 & 200 yard, since that is where I will be most of the time. Not sure what a DSM rifle is, and while SPR is Special Purpose, not sure what that looks like. This rifle is a non-competition, benched gun (maybe some prone some day), at a range, paper targets. The planned configuration is as follows.

SunDevil lower and upper receiver.
Rock River Arms lower parts kit.
Krieger barrel, .920" at muzzle, 22" long (maybe 20"), twist ???.
Young National Match chrome bolt assembly.
JP single stage 3.5" trigger (JP will install).
A2 or Magpul PRS stock.
JP adjustable gas block
JP VTAC free float handguard
Bushnell 4200 6 - 24 x 50 tactical scope.
TPS, Burris P.E.P.R., or Armalite scope mount.
Handloaded ammo. Forster and/or Redding equipment.

- Phil
 
#10
Re: AR-15 - Looking for Top Accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: doorkicker</div><div class="ubbcode-body">Shoot Monty an email, he can get you squared away with a Compass Lake turned Douglas barrel and he's in Coronado.

http://www.centurionarms.com/products.html

***You don't need 22", a 16-18" barrel will take you to 750yds with 77/80gr bullets </div></div>

Thanks for the link. I will contact these people. I know I really don't need a 22" barrel, but do not care for the look of 16" and 18". 20" is OK, and 24" looks too long. But, the shorter barrel is stiffer and may be more accurate because of it, so may go a bit shorter.

- Phil
 
#11
Re: AR-15 - Looking for Top Accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jason280</div><div class="ubbcode-body">Phil,

You really need to figure out what type of shooting you will be doing the majority of the time, and set your rifle up accordingly. Many people, and I have done this myself, set up a rifle for the type of shooting they <span style="font-weight: bold"><span style="font-style: italic">think</span></span> they are going to do instead of what they are <span style="font-weight: bold"><span style="font-style: italic">actually</span></span> going to do.

Now, that's not to say you can't set up a rifle that excels at both. Personally, I am currently building a rifle to use out to 675 yards, and my predicament is similar. I shoot on a 300 yard range, and rarely get an opportunity for 300+ distances. However, there is a club less than 1.5 hours away that offers distances up to 700 yards, and there is the slight possibility I will be shooting at that distance as well. So, I am building a rifle that will get me to 700 yards. The barrel I have ordered is a stainless Lothar Walther 20" 1:8 twist, with a contour similar to the Kreiger DCM. I plan on shooting 75-77gr bullets over Varget, but I can always shoot lighter bullets for shorter distances.

Remember, you can always get by with too fast of a twist for lighter/shorter bullets, but you can rarely get by with a slower twist for heavier/longer stuff. </div></div>

Good point. Yes, I WANT to shoot at longer ranges, but I have to drive 2 hours to get to a range longer than 200 yards, and I will not be doing that very often. Even the my local range only opens up the 200 yard range on special days, with the 100 yard the only distance available at any time. So, most rounds shot out of this gun will be 100 and 200. What bullet and twist is optimal for that, and would a bullet and twist for longer distances compromise accuracy at shorter distances?

- Phil
 
#13
Re: AR-15 - Looking for Top Accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Plasmech</div><div class="ubbcode-body">2 words:

Larue, and Noveske. </div></div>

Thats three
smile.gif
I agree, both are very good companies
 
#14
Re: AR-15 - Looking for Top Accuracy

Like mentioned above Larue, Noveske, Compass Lake, and don't forget White Oak Armament.

Remember if sending your upper to Krieger, they will chamber and set it up tight unless you instruct them to do it differently. Don't expect to feed any old ammo thru it especially 5.56 mil stuff.

 
#15
Re: AR-15 - Looking for Top Accuracy

Phil3, I may have participated in the older thread you mention. I have set up an AR-15 that I shoot in F-T/R to 1000 yards. The barrel is a Krieger, 26 inch with a 1:7.7 tist and their 5.56 Match chamber (they chambered it and fitted it to my upper). This chamber is tight for excellent accuracy, but allows me to load the 80gr bullets that I favor because the leade is long.

I use 80gr bullets at all distances from 300 to 1000 yards because I need the maximum accuracy and the best wind "cheating" I can get in a .224 bullet.

If I were to setup a precision AR for 100 and 200 yard paper targets with the occasional 600 yard shoot, I would do very close to what you are doing with the following comments.

I would get a 20 inch barrel, this will be perfect for 100/200 and will work very well for 600.

I would not get the adjustable gas thing, I think that's just a solution in search of a problem and may introduce problems of its own.

After a few years and many thousands of competition rounds fired by my Geissele trigger, you will have to pry it from my dead cold trigger finger. It is the best, bar none.

I have a PRS stock, and it's great for prone shooting.

I absolutely love my Tubb pistol grip, I have large hand with very long fingers.

Now for ammo. For the 100/200 yard range, I have used the 52gr SMK with great success in my 1:8 and 1:7.7 barrels; like little lasers. You may also want to look at some flat base bullets which are usually more accurate at close range than boat tails. I only use boat tails because of the distances at which I shoot.

I find the 69SMK to be more accurate than the 77SMK, but I don't use either one now, only 80JLK. Berger also makes some VERY FINE bullets.

Good luck on your build.
 
#16
Re: AR-15 - Looking for Top Accuracy

I would echo a lot of what Sig685 posted with a few differences.
I really like the JP triggers, they are robust, last a long time and are good for a lot of different disciplines.

If you want a 22" barrel get one, it can always be cut shorter. Will also make it easier to attain the velocity you are after.
1 in 8 twist will work great! I've shot 40 gr. Nosler ballistic tips with mine and they are like little lasers.

You have to single load the 80gr. SMK so a "bob sled" will help with that. Might want to open up the ejection port a little unless you have really skinny fingers. I'm loading 80 gr. smk at 2.430 which is a bit short but .006 off lands and getting 2850 fps out of a 24" barrel.

If your interests take a turn you can always build another upper to fit the needs of what ever it is.

Good luck sounds like a fun project!
 
#17
Re: AR-15 - Looking for Top Accuracy

I have a 1:7 OlyArms PCR-1, and it's sub-MOA accurate with factory heavy bullets, and 1/4-MOA accurate with 80 gr VLD handloads. It's a 24" bull barrel of no special distinction, but it's been cryo'ed. The 80's hold really well to 600 yards if you get their MV high enough. I've never shot it at 1000 yards, so it's possible the 80's would still do OK for that range as well, but I doubt it.

You should be fine with a slower twist and a shorter and 60-70 gr. bullets out to 600 yards. If you don't feel like handloading, get a twist that's ideal for 69 gr. factory match ammo. I'd guess a 1:8 or 1:9 20" bull barrel would be great for that. Once you decide on what ammo you want to shoot with it, just ask whichever armorer will get you the barrel and they'll let you know what to get.

I ordered mine with a match set trigger from OlyArms, but not sure who made the actual trigger. This was back in the late 90's, so there weren't a lot of manufacturers producing quality stuff for AR-15's then.
 
#18
Re: AR-15 - Looking for Top Accuracy

If you feel the need to try and impress people around arf.com, lightfighter, or whatever; go and get some larue or noveske. Its not needed. Some people feel they need "Shine," lolz. You just have to make sure the small parts are quality and it'll all run as intended.

Krieger's 7.7 twist will be just fine for you at 100,200, it shines at 600+ when you are used to shooting that far.

You can run 52smks, 68s or 69s short and 75/77s long.

No need to over-analyze it.
 
#19
Re: AR-15 - Looking for Top Accuracy

Make sure the Sun Devil upper will work with whatever FF handguard you choose. I had to have my Troy rail system custom fitted because the SD uppers are wider than standard at the front.
 
#20
Re: AR-15 - Looking for Top Accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cyberpuppy42</div><div class="ubbcode-body">(snip)

I've never shot it at 1000 yards, so it's possible the 80's would still do OK for that range as well, but I doubt it.

(snip) </div></div>

Understood. Since you speak from experience, do do you think I should return my LR plaque and wins and my lower my LR F-Class classification to Marksman? Also, you should send an email to the USAMU telling them you do not think they should be winning matches with their V8 loads.

Or you might just want to stand out of the way and watch while others do what you think is impossible.
 
#21
Re: AR-15 - Looking for Top Accuracy

Might want to also look at Larue and Nightforce one piece scope mounts.

The Geissele trigger is very nice, you should try one if you can.

I don't see the point of single loading a AR, but thats JMO.

-dan
 
#22
Re: AR-15 - Looking for Top Accuracy

For $590 to $700 you can get a turnkey upper from White Oak Armament in varmint or match configuration. I would go 1:7 twist. If you don't like their round float tube, buy a Badger Ord Stabilizer Handguard. Maybe WOA will even install it on your upper if you send it along? With Warne Maxima QD or TPS rings in Med or High height, you will be set.
 
#23
Re: AR-15 - Looking for Top Accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Sig685</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cyberpuppy42</div><div class="ubbcode-body">(snip)

I've never shot it at 1000 yards, so it's possible the 80's would still do OK for that range as well, but I doubt it.

(snip) </div></div>

Understood. Since you speak from experience, do do you think I should return my LR plaque and wins and my lower my LR F-Class classification to Marksman? Also, you should send an email to the USAMU telling them you do not think they should be winning matches with their V8 loads.

Or you might just want to stand out of the way and watch while others do what you think is impossible. </div></div>

No need to be pissy about it. I said it's just my opinion and NOT based on my experience shooting at 1000 yards with this round... Not sure why the sarcasm about me 'speaking from experience' when I clearly stated otherwise. Did I attack you personally somehow in my reply? Why the venom? I was just answering the OP's question with my experience...

EDIT: I just read your previous post above and I can understand your confusion. Rest assured that if I take issue with something you write I'll quote it. You're assuming I read your reply and responding to it, and you know what happens when you ASSume...
 
#24
Re: AR-15 - Looking for Top Accuracy

Thanks to all. I want this AR to be very accurate, so forgive my efforts to make the best choice. The info here is certainly helping! I thought I would summarize what has been said so far, and also include information sourced from a few other sites, as well as e-mails to me from a bullet and barrel maker. Hopefully this will be of help to others. Sorry for the compressed formatting, but could not make it look any nicer.

<span style="text-decoration: underline">Weight Twist Source</span>
80 G 1:7” or 1”8” Forum
69 – 80 1:8” Forum
52 – 69 1:9” Forum
75 – 77 1:8” Forum
52 1:8” and 1:7.7” Forum
80 1:7.7” Forum
40 1:8” Forum
80 1:7” Forum
69 1:8” or 1:9” Forum
52 – 77 1:7.7” Forum
50 – 55 Gr Flat Base 1:14” Berger
70 - 73 Gr Boat Tail 1:9” Berger
75 – 82 Gr Boat Tail 1:8” Berger
90 Gr Boat Tail 1:7” Berger
90 Gr 1:6.5” Krieger
69 – 80 Gr 1: 7.7” Krieger
55 – 69 Gr 1:9.0” Krieger
Up to 55 Gr 1:12.0” Krieger
Up to 55 1:14” 6mmBR
55 – 65 1:12” 6mmBR
66 – 73 1:9” 6mmBR
80 1:8” 6mmBR
90 1:6.5” or 7:7” 6mmBR

From Berger in an e-mail to me.

I think the 50,52, or 55 gr flat base will be a great place to start for a very accurate short range bullet. If you want something a little more wind resistant for longer ranges, then the 70 VLD and 73 gr BT are excellent choices that shouldn't exceed your magazine length.

From Berger in an e-mail to me.

For ranges up to 400 yards max, I recommend the 1:9" twist. This will allow you to shoot bullets up to the 70 gr VLD (and honestly, you can usually shoot the 75 VLD in a 1:9" twist too).

Heavier bullets than that are not necessary for under 400 yards. Also, the 1:9" twist isn't too fast for the lighter bullets, all the way down to 30 grains. I hesitate to go as slow as 1:12" because it will limit your option to use heavier bullets.

From Krieger in a e-mail to me.

The best twist rate is dependent on the heaviest bullet you want to use. If a 69 grain bullet is the heaviest, use a 1-9 twist. If you want to use up to the 80 grain bullets, use the 1-7.7 twist.


----------------------

All my rounds must be come from the mag, I am not doing single loading. I don't know how big the bullet can get before it won't fit in the mag. With the vast majority of shooting to be done at 100 and 200 yards, I will be using lighter bullets, and it would appear that a 1:9" twist is fine, and I would have some room to try longer distances, although not too far. 1"7.7", the other Krieger option would work too, but the manufacturers appear to err more on the side of a slower twist. I probably over analyzed this, but I did learn a lot!

Thank you.

- Phil
 
#26
Re: AR-15 - Looking for Top Accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: deersniper</div><div class="ubbcode-body">Might want to also look at Larue and Nightforce one piece scope mounts.
The Geissele trigger is very nice, you should try one if you can.
</div></div>
+1 I'm very happy with my NF uni-mount. LaRue mounts are built like tanks, but their lever locks gall the shit out of my weapons and I'm not a fan of that!
mad.gif


The Geissele high-speed match trigger is incredible!

Recce build I finished yesterday...

IMG_1638.jpg


KAC M110 adj. buttstock
Noveske N4 lower
YHM upper
Geisslie high-speed match trigger
Ergo grip
PRI Gas Buster CH
KAC 300m BUIS
Nightforce Uni-mount
Nightforce 2.5-10x24 ill. MD compact scope with BC caps
Daniel Defense 12/0 Lite Rail
Daniel Defense QD sling stud
Douglas 16.1 barre
VLTOR low-pro gas block
mid-length gas system
Ops Inc brake & collar
Ops Inc 12th MBS suppressor
KAC bipod mount
Harris 6-9 S/Notched/Pod Loc
 
#27
Re: AR-15 - Looking for Top Accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Phil3</div><div class="ubbcode-body">Thanks to all. I want this AR to be very accurate, so forgive my efforts to make the best choice.
(snip)
All my rounds must be come from the mag, I am not doing single loading. I don't know how big the bullet can get before it won't fit in the mag. With the vast majority of shooting to be done at 100 and 200 yards, I will be using lighter bullets, and it would appear that a 1:9" twist is fine, and I would have some room to try longer distances, although not too far. 1"7.7", the other Krieger option would work too, but the manufacturers appear to err more on the side of a slower twist. I probably over analyzed this, but I did learn a lot!

Thank you.

- Phil </div></div>

As Conqueror correctly pointed out, the heaviest bullets that are mag-length capabale are the 77gr SMK, and the 75gr Hornady HOBT (not the A-Max.) Either of these bullets will take you to 600 yards if needed as will the VLDs from Berger. If you choose the 1:9 twist, I think you will be fine, I just like a 1:7.7 ot 1:8 twist to stabilize the 80s, which are definitely not mag length.

The other aspect you need to consider is the chamber itself,for top accuracy you would need a tight match chamber, but just so you know I use small base dies for the ammo of my 5.56 Match chambered Krieger barrel; that chamber is very tight. I can actually fit the fired case in a guage it is so tight but the run through the S/B bushing die keeps everything nice (very little effort required.) That being said, I would not want to depend on this rifle to feed ammunition that I did not handload I would be afraid of failures to feed and failures to eject. All this to say that unless you are meticulous about the ammo you will feed it, you may want to consider a Wylde-type chamber.
 
#30
Re: AR-15 - Looking for Top Accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: doorkicker</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: deersniper</div><div class="ubbcode-body">Might want to also look at Larue and Nightforce one piece scope mounts.
The Geissele trigger is very nice, you should try one if you can.
</div></div>
+1 I'm very happy with my NF uni-mount. LaRue mounts are built like tanks, but their lever locks gall the shit out of my weapons and I'm not a fan of that!
mad.gif


The Geissele high-speed match trigger is incredible!

Recce build I finished yesterday...

KAC M110 adj. buttstock
Noveske N4 lower
YHM upper
Geisslie high-speed match trigger
Ergo grip
PRI Gas Buster CH
KAC 300m BUIS
Nightforce Uni-mount
Nightforce 2.5-10x24 ill. MD compact scope with BC caps
Daniel Defense 12/0 Lite Rail
Daniel Defense QD sling stud
Douglas 16.1 barre
VLTOR low-pro gas block
mid-length gas system
Ops Inc brake & collar
Ops Inc 12th MBS suppressor
KAC bipod mount
Harris 6-9 S/Notched/Pod Loc
</div></div>

Door Kicker

I love my M110 stock, hope they sent you the shorter stock screw otherwise your buffer will bottom out. Oh yeah, I found out the hard way!
 
#31
Re: AR-15 - Looking for Top Accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: shooter65</div><div class="ubbcode-body">Randall Rausch
www.ar15barrels.com
Specializing in barrel threading, machine work and custom builds.


Randall knows his shit and will build you one hell of an AR. </div></div>

I hear he does know a lot, but his site says taking no more orders for custom barrels at this time. and his e-mail address bounces my message back. I sent him a private message on www.calguns.net, and will see what he says.

- Phil
 
#32
Re: AR-15 - Looking for Top Accuracy

Sig685,

Chambering is, admittedly, a mystery to me, and have not done any reloading, which I will do. I really need a mentor.

I know I need a tight chamber, and probably a short freebore area for the bullets I shoot. I really don't know how to go about requesting this. Krieger says they will chamber in .223 Remington for 40 - 69 bullets and 5.56 match for 70 grains and over. I was going to go with .223 since I will be shooting at shorter ranges with lighter bullets. I don't know if this is optimal or whether custom chambering is preferred, or...? Like I said, I am lacking in knowledge here. The Wylde is looser I know, but I will be reloading all my ammo. If by chance, I need to run factory ammo through it, are you saying that the Krieger chamber may be so tight, it will have problems? Even if a 40 - 60 grain bullet per Krieger's specs?

I do apologize for the naive questions, but am reading all I can to learn, but reloading and chambering is somewhat of a mystery.

- Phil
 
#33
Re: AR-15 - Looking for Top Accuracy

Your questions are not naive, they show that you are thinkignthings through and that you have a goal in mind and are making sure your plan is correct.

For what you are considering, I would suggest you look at the .223 Remington chamber. It should also chamber good factory ammo with no problems, but I am uncertain about reloads from others. You should only use cases that have been fired in that rifle and simply resize them properly.
 
#34
Re: AR-15 - Looking for Top Accuracy

He is still doing work. I shot with him yesterday. Matter of fact he brought an AR 10 with him that he built for someone. He will repsond to your PM later as I know he is out in the desert working on the shooting range.



<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Phil3</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: shooter65</div><div class="ubbcode-body">Randall Rausch
www.ar15barrels.com
Specializing in barrel threading, machine work and custom builds.


Randall knows his shit and will build you one hell of an AR. </div></div>

I hear he does know a lot, but his site says taking no more orders for custom barrels at this time. and his e-mail address bounces my message back. I sent him a private message on www.calguns.net, and will see what he says.

- Phil </div></div>
 
#35
Re: AR-15 - Looking for Top Accuracy

Thank you. I am feeling better about making the right decisions. Will wait for Randall's response. At this juncture, it appears a chamber in .223 Remington, shooting up to 69 grain bullets (or thereabouts), in a 1:9 twist barrel should do well at 100 and 200 yards.

I do have concerns about the heavier bullets being jammed into the lands and causing overpressure. Or is that even an issue with a .223 Remington chamber and bullets up to 69 grain? An issue if I reload and don't seat the bullets as far (don't know I would do that?). I am no gunsmith so how are these things checked or measured?

- Phil
 
#36
Re: AR-15 - Looking for Top Accuracy

5.56/nato match is the way to go. Do not want anything to do with a .223 chamber in an ar-15. Your first response is spot on call Compass lake and order what length barrel you want. They'll do the rest.
 
#37
Re: AR-15 - Looking for Top Accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: criver</div><div class="ubbcode-body">5.56/nato match is the way to go. Do not want anything to do with a .223 chamber in an ar-15. Your first response is spot on call Compass lake and order what length barrel you want. They'll do the rest. </div></div>

I left e-mail for Compass Lake. Why don't I want anything to do with a .223 chamber in an AR-15? Sig685 suggested I use the .223 chamber. ???

- Phil
 
#38
Re: AR-15 - Looking for Top Accuracy

<span style="font-style: italic">Bill Wylde - .223 Wylde chamber:

The case dimensions of the Wylde reamer are that of one of the NATO prints. Not a thing tight about it. As I recall, there were two NATO prints in use. I don't recall the print number used, but do have it in old records somewhere.

Throating was about the only change. The decision was made to make the freebore diameter .2240" as a good bullet seal. That done, excess freebore made little difference to accuracy. One of the reasons the magazine length 69's shot so well in the chamber. It so happened that the 80 grain Sierra seated to the lands was about ideal at .2470" OAL. Simple luck.....All of it.

The initial reamer(designed in 1984)was mainly geared toward Canadian 5.56 ball, as I was experimenting with their issue ball for competitive purposes. This operation was slow in getting off the ground, and really didn't start happening until about 1990. The use of 5.56 NATO ball in Canada was a short lived affair. Handloads were allowed in about 1994.

Just prior to this time the AR's were gaining great strength in the U.S. The military finally got involved. The rest is history.

You might ask how the the 62 grain 5.56 ball worked for Canadian LR prone shooting to 1,000 yds? It was supersonic in barrels of 28", and longer. It also was very competitive with the 147 grain 7.62 ball in use there at the time. The wind drift differential at long range (7.62/5.56) was about 15% in favor of the 7.62. </span>
http://www.thehighroad.org/showthread.php?t=52286

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Why don't I want anything to do with a .223 chamber in an AR-15?</div></div>
If/when you shoot mil.surp ammo.
 
#40
Re: AR-15 - Looking for Top Accuracy

What we have here is the classic failure to communicate.

I am using the terminology directly from the Krieger website about the chambering service they provide.

On page 12 of their brochure at their website, which you get to by clinking on "DCM and AR-15" on the right and scrolling down some, you will read:

"Chambering: chambered, headspaced, extension installed, ready to be assembled by you to your rifle. This is the most asked for service with our AR-15 barrels. Please specify chamber, either .223 Remington (for 40-69 grains) or 5.56 Match (for bullets 70 grains and over.)" This service costs $100.

Since you are insisting that you only want to shoot the short distance, with light bullets and you want a 1:9 twist, I suggested this would be the proper option to fit your parameters.

Now you are saying you want to be able to shoot the heavier bullets but you say you are worried about jamming the bulelts in the lands and causing overpressure. I can't help but wonder why you worry about longer bullets when you already decided on a 1:9 twist which will not statically stabilize the longer bullets.

I originally suggested to you go with the 1:7.7 twist and if that had been your selection I would have suggested the 5.56 Match chambering to go with it. The only difference between Krieger's .223 Remington and 5.56 Match chambering is the length of the leade, at least that's my understanding. In essence, that is really the main difference between .223 and 5.56 in the real world.

If you go with another builder they can provide various chamberings for you, which will further confuse you. Be prepared to hear Hollinger, Wylde and various others. Whatever you do, match the twist to the chambering. Krieger will rifle the barrel, irrespective of the final builder. I did not mean to confuse you, only to prepare you for that decision.

In my rifle, I went with a 1:7.7 twist with the 5.56 Match chambering from Krieger and I never regretted it.
 
#41
Re: AR-15 - Looking for Top Accuracy

I think I am getting in over my head...I just don't fully understand the terminology, the impact of the different dimensions, etc. It is one of those situations where I don't know, what I don't know, but should or need to know, to make right decisions. Lots of information, but not really able to make good sense of it, because much is over my head. Rather like being in graduate school before you took undergraduate courses.

I will check with Randall Rausch at www.ar15barrels.com, and see what he says, but wish I knew more so I could say something more meaningful than, "here is what I am shooting and how...please make me a barrel". I am one of those people who needs to understand what is happening under the hood.

I appreciate all the help here.

- Phil
 
#43
Re: AR-15 - Looking for Top Accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Phil3</div><div class="ubbcode-body">I think I am getting in over my head...I just don't fully understand the terminology...</div></div>
Phil, if you are firing .223 ammo loaded with C3PO you should be fine, just be careful when shooting 5.56 loaded with R2D2
grin.gif
 
#45
Re: AR-15 - Looking for Top Accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Sig685</div><div class="ubbcode-body">What we have here is the classic failure to communicate.

I am using the terminology directly from the Krieger website about the chambering service they provide.

On page 12 of their brochure at their website, which you get to by clinking on "DCM and AR-15" on the right and scrolling down some, you will read:

"Chambering: chambered, headspaced, extension installed, ready to be assembled by you to your rifle. This is the most asked for service with our AR-15 barrels. Please specify chamber, either .223 Remington (for 40-69 grains) or 5.56 Match (for bullets 70 grains and over.)" This service costs $100.

Since you are insisting that you only want to shoot the short distance, with light bullets and you want a 1:9 twist, I suggested this would be the proper option to fit your parameters.

Now you are saying you want to be able to shoot the heavier bullets but you say you are worried about jamming the bulelts in the lands and causing overpressure. I can't help but wonder why you worry about longer bullets when you already decided on a 1:9 twist which will not statically stabilize the longer bullets.

I originally suggested to you go with the 1:7.7 twist and if that had been your selection I would have suggested the 5.56 Match chambering to go with it. The only difference between Krieger's .223 Remington and 5.56 Match chambering is the length of the leade, at least that's my understanding. In essence, that is really the main difference between .223 and 5.56 in the real world.

If you go with another builder they can provide various chamberings for you, which will further confuse you. Be prepared to hear Hollinger, Wylde and various others. Whatever you do, match the twist to the chambering. Krieger will rifle the barrel, irrespective of the final builder. I did not mean to confuse you, only to prepare you for that decision.

In my rifle, I went with a 1:7.7 twist with the 5.56 Match chambering from Krieger and I never regretted it. </div></div>

Thanks for your response.

I have read that Krieger section. I am not insisting on shooting at short ranges. Unless I take a four hour round trip, 100 and 200 yards is it. Nor do I necessarily want a 1:9” twist…I only thought it would be appropriate based on information from Krieger and the fact that people here are using faster twists for bullets heavier than appear to be preferred for short range.

I have no desire to use heavier bullets. My comments and questions were aimed at ensuring that bullets Krieger says I can use for 1:9" twist (up to 69 grain), would be safe, and not jammed into the lands with a .223 chambering. A rather pointless question on my part, since Krieger wouldn't include 69 grain if it wasn't safe. Just a safety question.

The “leade” is the freebore? If so, then it permits me to shoot any weight bullet I would expect, but that would be pointless given the 1:9” won’t work with long stuff anyway. Not that I will be shooting it.

The real question is, what bullets shoot most accurately at 100 and 200 yards. Form what I can find, that would be lighter, flat based rounds, mandating a slower twist, meaning I can use a shorter lead, or the .223 Remington chambering. Do I have anything wrong?

I appreciate your patience.

- Phil
 
#46
Re: AR-15 - Looking for Top Accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: shooter65</div><div class="ubbcode-body">I just Pm'd Randall for you. </div></div>

Thank you, appreciate the help. - Phil
 
#47
Re: AR-15 - Looking for Top Accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: doorkicker</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Phil3</div><div class="ubbcode-body">I think I am getting in over my head...I just don't fully understand the terminology...</div></div>
Phil, if you are firing .223 ammo loaded with C3PO you should be fine, just be careful when shooting 5.56 loaded with R2D2
grin.gif
</div></div>

So if I did reload with such exotica, would my round be worth as much as this?

http://www.gunbroker.com/Auction/ViewItem.asp?Item=128271630

- Phil
 
#49
Re: AR-15 - Looking for Top Accuracy

Gunsmiths generally use the Greenhill Formula to determine the optimal twist for a given bullet. The formula is T=150(d/r) for velocities from about 1500 to 2800 fps. Substitute 180 for the 150 value for velocities exceeding 2800 fps. "T" is the twist rate. "d" is the bullet diameter. "r" is the bullet length to diameter ratio (length of bullet divided by diameter). In .308, it works out fairly well. Sierra 168 grain Matchking is 0.308 inches in diameter. Bullet length is about 1.210 inches so we have a length to diameter ratio of 3.929. Plugging this value into the formula and using the 150 constant (the proven best velocity for the 168 grain MK is 2550 - 2600 fps), we get T=150 x (.308/3.929); T=150 x 0.078; T=11.76 inches or 11 3/4 inch twist. One rotation of the bullet for every 11.76 inches of barrel traveled. This is very, very close to the "standard" 12 twist barrels on our PSS's and on my Chandler and one of the reasons they shoot the 168s so well. The 175 Matchkings do not perform as well in the 12 twist barrels. Again diameter is 0.308 inches. Bullet length is 1.257 inches, resulting in a l/d ratio of 4.081. Plugging into formula (optimal velocity is 2500 to 2550 fps so we will use the 150 constant again) T = 150 x (.308/4.081); T = 150 x 0.0755; T = 11.320. That approximate half inch twist difference makes a big difference in my guns. 12 twist barrels tolerate 175s but do not excel with them. 10 twist barreled .308 tactical rig, built by John Eckenrode on a Remington 700 SA in a McMillan A2 stock with Ross guard and Leupold 3.5 x 10 M3 LR, eats 168s, 175s, 180s and 190s alive. The general rule of thumb is to use the fastest twist you can tolerate and match to the longest bullet (usually heaviest) you intend to use for the life of the barrel. Greenhill was a Brit and developed it back in the late 1920s.
 
#50
Re: AR-15 - Looking for Top Accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: shooter65</div><div class="ubbcode-body">I just Pm'd Randall for you. </div></div>

Randall responded back. He says he does not know when he will resume taking barrel orders, being so busy with routine work.

- Phil
 
You must log in or register to reply here.

Similar threads

Jokerkg
First AR-15 SPR Build: Barrel Suggestions?
Replies
15
Views
677
oldrifleman
oldrifleman
kthomas
Question for the accurized AR-15 crowd...
Replies
57
Views
1K
LRRPF52
LRRPF52
I
Best bullet choice for accuracy .223 Rem up to 300 Yards
Replies
34
Views
1K
dschr582
D
M
AR Barrels
Replies
11
Views
590
brassninja
B
Thumper580
What determines brass ejection angle/position
Replies
7
Views
308
Ex E6
Ex E6
Top Bottom
Back
Home
Forums
Merch
Alerts