AR Build

[jjasilli]

My son & I just finished building 3 AR-15 uppers.  Here's a photo of our high-end project, temporarily sitting on an upgraded RRA lower receiver.  The design goal is a bench rest AR-15 based on a space gun look, capable of high accuracy under 1/2 moa @ 100 yds.  The upper consists of a custom Kreiger barrel chambered for .223, Precision Reflex Gen Tech free-float forearm, DPMS lo-pro upper receiver; Weaver T-36 Scope; RRA scope mount; and upgraded bolt carrier group (not visible in photo).  

A custom lower receiver build is in the works, probably to include a space stock & Gieselle 2 stage trigger.

While sighting-in and breaking-in the barrel and bolt carrier, it's putting 2 to 4 bullets in 5 shot groups through the same hole at 100 yds -- exceeding our expectations at this point.  

[Ritchie200]

That is a really nice looking system!  Black Hills ammo?  I'd say that would exceed anyone's expectations!  How much do you think you have in it?  I have toyed with the idea of building one as I would like to maybe try some three gun stuff.  Looks like fun!  However, I am low on funds as I just purchased my dream - a Savage 110BA in 338 Lapua.  Now to save/invest in scope and reloading supplies....  It will be another 6 months before I can afford to shoot it!

Jim

[jjasilli]

Ammo:  Handloaded by my son; he's away. It was either 67 or 69gr Hornady or Sierra bullets; brass either new or once fired, fully re-sized Lapua.  Brass was flash hole uninformed, and deburred inside.  Necks trimmed on LE Wilson trimmer to within .001".  Powder charge a tad under max.  We still need to take headspace and bullet jump measurements of this chamber, to fine tune handloads for re-sizing, shoulder bump and bullet seating depth.  

Expectations.  Cool Savage 110BA!  The truth about AR-15 accuracy is slowly being admitted.  Within their caliber comfort range, AR-15's are more accurate than bolt action rifles.  No one really knows why.  This defies traditional thought for a semi-auto, and is hard to accept but true.  Out of the box, a factory AR-15 from a reputable company, shooting the specific commercial ammo that it likes (trial & error), will shoot sub moa @ 100 yds.  Customized, accurized bolt action rifles shooting tailored handloads have a hard time achieving 1 moa.  But the AR platform does not scale up well.  It's not great for high performance calibers above 6mm.  An AR-15 in .308 wants to fall apart.  Also, there may be legal or personal preference reasons to prefer a bolt action rifle.

Per Harry Potterfield of MidwayUSA:  the inherent accuracy of an AR-15 can be significantly improved with these 4 upgrades:  match or varmint quality barrel; free-float handguard; better sight or optic system; and better trigger/trigger assembly.  Such improvements should produce consistent 5 shot groups of .5 to .75 moa.  By going top quality on all criteria, my son & I are seeking consistent single hole accuracy @ 100 yds.  We already have .5 moa or better with our first few 5 shot groups.  


Approx Costs.
* Kreiger barrel, fluted & chambered EDIT: & Crowned with gas block & tube:  $550; $650
* Precision Reflex Gen Tech free-float forearm (the only free float forearm we could find with a flat, beavertail bottom): $395
* stripped DPMS lo-pro upper receiver: $90
* upgraded bolt carrier group:  $150
* stripped lower receiver:        $184
* lower receiver parts kit:         $60
* Castle nut and endplate:       $10
* space stock:                      $300
*JP Enterprises buffer system: $135
* Gieselle trigger:                  $240 (Don't know yet if we'll want an upgrade to their pricier models)

Subtotal:                           $2114 $2214
Scope & Mount:                     500
Grand Total:                       $2614 $2714

Not cheap considering you can get a serviceable AR-15 for about $800.  But I suppose this build is equivalent to a custom job hired-out for about $4500 - $7500.  Unfortunately, diy builds probably have no resale value.  

Also note: some special tools & regular tools are required along with a proper workspace, etc. - at least another few hundred dollars. Plus a reasonable learning curve.

[Ritchie200]

You know, a custom bolt gun would need far more expensive work to achieve the groupings you got - and you still don't have it dialed in yet!  Amazing!  Yeah, those 308's on an AR platform are scary!  And I dont know anyone who is happy with the accuracy.  One of the magazines did a multi-gun AR test with like 50 different rounds.  Some eye-opening results!  Like you said, an off the shelf model will shoot extremely well with the right food!  I want to see your creation again with the new parts!  Is this for competition or pleasure?  Who do you buy your parts from?  You know you cant put a price on any father and son project!

Speaking of scary... Have you seen the Anzio 20-50?  A 20mm case necked down to a .50?  Something like 3600fps!  Supposed to be accurate out to 3,500 yards.  The caliber keeps it below the big-boy-toy-tax and registration.  I think there may be some extreme pressures in that round....

Jim

[jjasilli]

Other AR-15 rounds.  I'm intrigued with the Grendel for hunting; and the Beowulf, 50 caliber but with pistol ballistics; also maybe 9mm so it can shoot pistol rounds; and .22LR.  Maybe a 6mm bench rest round.  But no specific plans at this time.  

Should be ordering new parts for the lowers soon; and will post the rest of the build.  One set of tests is done.  The new uppers all work right on our one completed lower.  And a Giesselle trigger is needed for this build.  The upgraded RRA two-stage trigger is a fine product, smooth & crisp, but too heavy a trigger pull for benchrest accuracy. My research shows that for an AR it's better to buy the trigger you want rather than modding a different one.  An actual trigger mod is above my "pay grade" anyway.  Polishing trigger parts is no problem, but the RRA is fine in that regard; it's specifically a pulling weight issue.

This build is for pleasure.  I wish we had time for competition.  I am getting drawn in that direction.  As one wag said:  You know you're in trouble when your hobbies get in the way of one another!  

We source most of our parts & supplies from MidwayUSA; Brownells & Sinclair.  Lately parts have been scarce, but that seems to be easing a bit.  My son drives a lot for work and blundered into 2 Stag Arms stripped lowers at a gun shop in the middle of nowhere.  

I was not aware of the Anzio 20-50; found this info on the web:  http://www.ar15.com/archive/topic.html?b=6&f=3&t=310948
http://ammoguide.com/?catid=445

I'm  not a big bore person.  .338 Win Mag *(Schultz & Larson) or 45-70 (Marlin) has been my upper limit.  I'm more into hunting, using target shooting to increase shooting skills.  With a deer in the sights it's re-assuring to know that I've performed the shot hundreds of times.

So far my longest shots have been 200 yds.  Group size stays consistent in terms of moa.  Our club has a makeshift 300 yd range and is building a 400 yd range.  So that's in the near future.

[Ritchie200]

Your opinion:

Stainless or chrome lined steel?
16 or 20"?
Twist?

The 6.5 Grendel is supposed to be the stuff!  What about the 300 Whisper?

Magnum Research builds a 45-70 revolver (BFR Line).  It has more fps and knock down than the SW 50Mag with far less recoil.  I know many are using it as a backup or primary for big dangerous game in Alaska - amazing cartridge considering it's like 150 yrs old!  I don't hunt anything but paper.  And steel.  And bottles.  And cans.  And even an occasional old bowling pin.....  

My gun club goes out to 600yrds. BUT I have taken a few lessons from these guys....
http://asymmetricsolutionsusa.com/

Jim

[jjasilli]

No one answer.  You need a firm design concept.  To shoot a specific competition your firearm must qualify for that.  What caliber do you want to shoot 600yds?  To keep a bullet on track at longer ranges, momentum is a must.  Momentum = mass x velocity.  A 223 has little mass so go to 77 or 80gr. (90 gr and up is available, but hard to get to fly right). Now you have max mass.  Note that except for Sierra 77's bullets over about 69gr will not fit an AR magazine and need to be hand inserted one at a time into the chamber.  

Next for velociity, a Wylde chamber with long throat is often used, because long bullet jump increases velocity; but at the sacrifice of some accuracy.  (Max accuracy will usually come from a tight .223 match chamber.) The combination of mass x velocity should yield 1 moa accuracy @ 600yds.  That's about 6" which may or may not float your boat.  It's good for competition with a 12" bullseye.

This assumes a premium barrel.  The longer the better.  At 24 or 26" a muzzle break is no longer needed, which eliminates a variable re accuracy.  A book could be written on barrel quality.

For better accuracy at that range a larger caliber can be considered, cause there's more bullet mass to start with.  Note that 6mm rounds burn out barrels rapidly like within  only 800 rounds.  

I'm not personally familiar with other calibers you mention.  

I hope these ideas are helpful.  Please post again for more specific info.  

[Ritchie200]

Oh no, the Savage is for the long stuff.  I want to build the AR for 3-gun competition.  So we are talking a few feet out to maybe 300yrds.  This will be a .223 rig as the other calibers I mentioned were for your benefit as they are supposed to be great for hunting.  So many barrel makers.  It's hard to figure out who is good because how can you believe the online reviews!  I agree a tight chamber is a must.  It looks like a lot of guys are staying shorter on the barrel to maybe aid in target acquisition.  I just do not know enough about the sport to be dangerous other than I think I can be competitive in each phase and it looks like a LOT of fun!  I have gone to a few shoots and am asking a lot of questions.  I really need some help on the AR as there is SO much "stuff" out there... 

If you go to that website I posted, you can see a few of the pistol classes I took.  Really cool, real life stuff.  Plus they have a sniper course out 2000+ yards.  My Savage and I are looking forward to that!  Hopefully in the next year or two.  Lots of $$$$$$$$$$.......

Jim

[jjasilli]

3-gun sounds great.  Wish I had the time and place. Hard living in Brooklyn, NY. 

Anyway, from what I see it's easy enough to get into 3-gun.  A large investment is not necessary for any of the firearms, at least to get started.  One forum states:  "A 18-20 inch AR that runs and will shoot at least 1 MOA. Put a good muzzle brake on it and a decent scope."  Any off-the-shelf AR from a reputable manufacturer will do that.  You'll eventually want an upgraded trigger -- most likely single stage.  Rapid fire is part of the competition, and single stage triggers tend to fire & recover faster than 2-stage triggers.  Another wish list upgrade: Brownell's carries a great muzzle break for about $115 (I think) that greatly reduces muzzle jump -- good for rapid fire. 

For short target distances lightweight bullets under 50gr down to about 30gr may be best.  Less bullet mass = less recoil, for better on target recovery time in the rapid fire portion of the course.  Those light bullets want a 1 in 12" twist rate. 

The tack-driving accuracy from a tight chamber is not needed for 3-gun; and is probably not worth the risk.  The risk in theory is that a tight chamber may cause cycling issues, which would be disastrous in 3-gun.  Standard loosey-goosey .556 chambering should give 1 moa or better w/o the risk of cycling issues. 

[Ritchie200]

Hey Jjasilli

Take a look at this article about the differences between .223 and 5.56.  With your experience, what is your take on this?

Jim

http://blog.cheaperthandirt.com/ar-15-223-mil-spec-5-56mm-chambers/?utm_source=newsletter&utm_medium=social&utm_content=chronicle0315&utm_campaign=20140315-social-newsletter-ar15-223-vs-milspec-556-blog-post