Full Custom 260 Build

[pagana]

My 1st build, let me know what you think.

Base Rifle: DPMS LR (Parts cheap and easy to find)
Barrel: Krieger 18LV port forward 3"
Extension: EDM'ed square .0001" Lapped to upper
Bolt: Front ground square .0001", bushed for small diameter firing pin .060" (.058" firing pin), front EDM'ed square .0001", timed at .001" clearance with headspace at 1.630"
Upper: Steel DPMS Honed to removed burrs, shimmed extension to .0003" clr., M4 ramps EDMed and polished, and squared front with custom lapping tool.
Handguard: YHM (Fulton) mated with custom barrel nut to increase rigidity, i.e. torques and clamps. Used this handguard design to adjust clr to gas block.
Gas Block: custom, infinitely adj. with custom gas tube
Trigger: CG with CS springs 1.5lbs.
Buffer Asm.: CS flat spring and carrier weight
Rings: WEDM and machined from tool stell to exactly match scope diameter

Built it specifically to see what an AR could do if blueprinted. Weighs a ton (over 19 lbs. as shown but shoots well (1st 4 break in shots into .350" @ 100 yds with #5 to .60" and 1st 5 rounds @ 300 yds at just under 1")


[img:center]http://s861.photobucket.com/albums/ab180/pagana/[/img]

 

[19Scout77]

Re: Full Custom 260 Build

What's up Brother! In reading the description I thought--man, that sounds like A-----'s rifle...I was right! Welcome aboard!

Eric

 

[Saito]

Re: Full Custom 260 Build

Here you go, gotta help you out...

 

[oldgrayone]

Re: Full Custom 260 Build

Nice looking build. Why did you go so heavy?

 

[pagana]

Re: Full Custom 260 Build

Its all the add ons that really bring it up. Rings are 1Lb. alone and the barrel nut, though aluminum, is heavy (3" long and solid). Then there is the Upper - steel. I used it because I wanted as rigid an interface as I could achieve to hang a heavy 27" tube on. I figured I would try to achieve what the platform could deliver as far as absolute accuracy is concerned.

 

[mdmp5]

Re: Full Custom 260 Build

well, how does it dance?

 

[pagana]

Re: Full Custom 260 Build

I only have 25 total rounds thru it thus far. I had the most difficulty getting it to feed reliably. I'll have targets after this weekend to post, but, as stated in the original post, it seems promising. I'm certainly not the best shot, but 1" for its 1st 5 shot group at 300 yards was more than acceptable. I have not tweaked the load. I merely added .001" extra or .002" total with a bushing to my bolt gun load.

 

[mdmp5]

Re: Full Custom 260 Build

1" at 300 yds? That is outstanding.

 

[Rovieairto]

Re: Full Custom 260 Build

A damn fine build!
I've been looking for one of those steel uppers for a while now.
Did you design the barrel nut?
I'm intrigued in how it clamps onto the upper.
I'll bet she kicks like a dead mule.

 

[pagana]

Re: Full Custom 260 Build

Given the weight, virtually zero recoil. I did design the barrel nut. The idea came to me when I saw the POF concept and thought, this really does nothing about rigidity. It's difficult to see in the pictures but the nut is timed and split down the middle with (3) 8-32 screws on either side. The nut is 3" long with threads for the handguard almost half the distance (why you can't see the screws). The slot is formed with WEDM which is why you can't see the slot. Since the barrel profile is round for the 1st few inches, and there is only .001" clearance, once clamped, the barrel to receiver is extremely rigid. I have the whole upper modeled, so let me know if you want a blue print for the nut.

 

[Rovieairto]

Re: Full Custom 260 Build

I would love it.
I don't have access to an EDM machine, so the split would just be a little wider than ideal I guess.
I'm building a custom upper right now and so I could have it made fairly quickly.

What software are you using?

 

[elkkid3]

Re: Full Custom 260 Build

Very nice lookin build.

 

[sobrbiker883]

Re: Full Custom 260 Build

Very cool and interesting rifle!



<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Toolmakr</div><div class="ubbcode-body">........The idea came to me when I saw the POF concept and thought, this really does nothing about rigidity.......... </div></div>
-with regard to the POF design, all by itself the barrel nut may only function as a heat sink/dump, but as part of the entire MRR design one cannot really say "this does nothing about rigidity".....

 

[pagana]

Re: Full Custom 260 Build

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Hamilton</div><div class="ubbcode-body">I would love it.
I don't have access to an EDM machine, so the split would just be a little wider than ideal I guess.
I'm building a custom upper right now and so I could have it made fairly quickly.

What software are you using? </div></div>

The upper is laid out in Solid Works. It was reverse engineered from the original parts as well as the dedicated parts purchased for this build (I wanted to have complete separate uppers).

 

[pagana]

Re: Full Custom 260 Build

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sobrbiker883</div><div class="ubbcode-body">Very cool and interesting rifle!



<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Toolmakr</div><div class="ubbcode-body">........The idea came to me when I saw the POF concept and thought, this really does nothing about rigidity.......... </div></div>
-with regard to the POF design, all by itself the barrel nut may only function as a heat sink/dump, but as part of the entire MRR design one cannot really say "this does nothing about rigidity"..... </div></div>

I agree with you that the handguard/receiver rigidity is much improved with the POF design. I believe this goes one step further and improves barrel/receiver rigidity as well. It is more like a barrel block concept for a bolt action or the "skeleton" concept of the RFB.

 

[bohem]

Re: Full Custom 260 Build

Wanna build me an upper?

That's very nice, I was happy with how my LR-260 shot until just now

 

[sobrbiker883]

Re: Full Custom 260 Build

I think its definately a well thought out design.
Good cycling with the gas port location, and would you mind sharing the port size? I'm thinking a 260 gas gun next, and would rather have a barrel made up than an off the shelf model....

 

[pagana]

Re: Full Custom 260 Build

Right now the port size is .085". If I had to do it over again I would either use 3/32" or move the port back 1" to give the system something to throttle (It currently cycles fine wide open with 123MKs). There really is nothing to this contour in that it simply a Krieger #18LV with a .935" cut for the block (you choose whatever length you like). The details are in the timing of the bolt/extension/barrel interface which I do have prints of and information for if you would like.

 

[sobrbiker883]

Re: Full Custom 260 Build

I'd definately be interested in any info you care to share-my email's in my profile, thanks!