I've decided recently to do a 5.45x39 build.

I've been a big fan of pencil contour barrels recently and in calibers other than 556. The cost of 545x39 has remained much better than 556 and about half that of 762x39.

I'm going to build a rifle that is balanced, if not slightly favoring the stock side.

The barrel will be a carbine gas melonite 1:8 .620 contour behind the gas block, which will be .625 and .620 forward of the gas journal to .5-28 threads.  I will also see if ADCO can dimple for a low profile gas block on a .625 seat.  I've endeavored to find a PWS FSC-YHM mount for probable suppressor use with my Ti 762.

The BCG will be semi-auto as my goal is to keep the front of the gun as light as possible.  Finding an auto-carrier makes for a decent price helped me choose otherwise here

The recent acquisition of some Noveske NSR9s at work has me really wanting to use one for this because of the thought put into designing sling attachment points, a very robust barrel nut, and polymer panel system which puts it's OD at less than some quad rails with no ladders or covers.

I will be making one of my lowers "skeletonized" by having part of the magwell cut on the port side and front to further mitigate weight. The area under the pistol grip will be bored through in 2 places. I may consider the removal of the rollmark as well.

The alternative rail system choice will be a Troy Extreme 9 with squid covers. I will also employ a Magpul RVG until a KeyMod VFG is designed and sold.

I'm going to use a M4 upper and remove the forward assist by milling it off as well. I've considered having part of the M4 toprail milled out as well.

I'm going to be taking before and after measurements to show what extra steps will actually do for balancing a gun without swiss-cheesing it to death.

The buffer tube will be a Vltor 5pos milspec with a CAR buffer.  I'm also going to install a Noveske QD sling endplate on the lower.  The stock will either be a B5 Systems SOPMOD or a Magpul STR. I know it might be counter-intuitive to put a heavier stock on the gun but I have considered balancing the gun toward the rear over weight reduction because I like stocks with nice cheekwelds and the ability to store batteries for possible employment of a TLR-1 or -3. I may also add a Vortex SPARC to it because of it's low cost, compact profile, and 2moa dot.  Backups will be MBUS gen2s.

I will soon be taking initial measurements the upper and lower to get my baseline weight and see where everything goes from here.

This is going to be a fun build, slightly challenging to keep my focus in not removing too much, and seeing what the results are.

The final phase of all this work will lead to a cerakote refinishing of all the shiny 6061 and 7075 parts.

Looking forward to updates

I finally took some photos of the upper and lower.

I've marked the areas where I think the most savings can be attained.  I forgot to photograph the front of the lower but it may only be 1-2oz up front anyway.  Perhaps even less.

The forward assist will be completely machined off to further reduce what I don't need on the gun.

To those who have run skeletonized lowers, are these areas kosher to machine out?




The barrel is going to get a full contour down to .620 behind the gas block, .625 at the gas block, and .620 forward.  I haven't seen the barrel I'm getting but I believe it has the M4 cut so my recontour plan may  change.

The NSR9s should be arriving soon and it will start to take shape.

I need to find a BCG for this also.  Maybe M1S can get me one.

Slowly updating.

I picked up a B5 FDE SOPMOD and installed the LMT 5 position tube from my SBR and installed the VLTOR on the LMT.

I'm down to 1 NSR9 at work now and am contemplating using the Troy 9 VTAC although the NSR would be awesome on this gun.  The B5 FDE is a nearly perfect match for the NSR FDE keymod panels.

I'm waiting to find a barrel in melonite and am probably getting it from Ballistic Advantage if I can't procure one locally.

instead of destroying that upper and lower, why not get a polymer lower and slickside upper?

For that matter, you'd probably save more weight cutting up an a1 style upper and using an unmodified slab side lower.  I think the ATF might get upset when you cut up a lower.

I'm in the middle of a lightweight .556 build. I bought a PSA carbine upper m4 contour and turned it down to .575 diameter rearward and in front of the FSB. I cut the barrel down to 16.125 with the hider pinned for additional weight savings. I'm going to use the factory plastic hand gaurds and use a trijicon rmr red dot. I've already put two coats of kg gun coat in flat black and it turned out great. Weight is 5 pounds iirc without bcg.

Eta: I took the PSA barrel off the A3 upper and swapped it with a dpms A3 upper without forward assist or a trapdoor. I am going to slot the upper on the eject side and make a side charger. Still waiting for a bcg though.

The ATF doesn't care if the non-description bearing part of a mag-well is cut out.  I'm not removing the serial number, nor the MFG name, city & state, or caliber marking.

I mentioned I might have the rollmark cut but i don't think it'll work here.

The other reason I didn't go with a polymer set was I have a friend who works for a MFG and he got me a stupid good deal on these parts.

I wouldn't want a polymer or carbon set simply because I've seen enough failure.  I'm not trying to remove metal where it's needed, only where I think there can be some removal.

Here's the current progress.

I just got a few things ordered in the last couple days.

I'll be running a DPMS auto carrier with a NiB coated 5.45x39 bolt.  I did decide to switch from the Noveske NSR9 to one of the new OdinWorks 9.5" KMod rail systems since the Odin is significantly cheaper.  It is nearly identical in weight, and only slightly wider.  I also figured out that it will accomodate a 1.5" OD sound suppressor, so anyone who wants to tuck a can in under it and still run KeyMod panels could likely do so.  I will be getting one to try out on my 10.5" 7.62x39 gun to see how well it works with that length barrel also.

I will also be trying to find a barrel for this through Ballistic Advantage since their's is melonited and I think that will be the best way to run for all the corrosive ammo I plan on shooting.

The initial optic choice will likely be a Vortex SPARC since I can't afford an Aimpoint Micro right now.

Any updates?

I'm about to pull the trigger on Ballistic Advantage's 14.5" pencil countour barrel for a lightweight build ... wondering if you have made any more decisions.

Any recommendations for a source for a bolt?  I have stripped carriers, but am having trouble sourcing a bolt.

Thanks in advance!

I just ordered the Ballistic Advantage carbine M4 profile barrel.

Carriers are tricky right now---I lucked out by finding a stripped carrier on the EE that I'm building up right now.  I also found a NiB coated 5.45 bolt too.

Once I receive it I'll do an initial assembly and test fire and see how the gun balances, weighs, balances, etc.  One of the $70 LPKs from AIM is on it's way and I'm also getting a Model 1 Sales enhanced firing pin for this since I'll be using my SBR lower initially until all my other lower parts arrive for the dedicated lower I have here.

I decided to use one of the new Odin Works 9.5" keymod rails we just got in at work.  They're very light, and the mounting system is very similar to the Noveske.  It's just going to cost me $100 less...

I feel the trade-off is worth it.

I may not do any further removal of anything on the lower's magwell or F/A on the upper.  I just want to get this upper running so I can shoot cheap again.

The barrel arrived from Ballistic Advantage all nicely wrapped and packaged and I wish I could've had them contour the gas block area down, but I'm going to weigh it before it gets sent to my chosen gunsmith---which will be either ADCO or Accurate Armory as AA is about 4 miles away.

Brownells is also sending the PRI Gas Buster latch for my charging handle that I picked up for $10.

The Spikes .625 gas block is en route as well, so there won't be any assembly until that barrel gets turned.

Soon----assembly and test fire.

Additional weight savings can be had by removing the dust cover, pin and the taps for it on the upper.
I have an SBR that has been running without dust cover since I built it,
and it is no dirtier than my 'with dust cover' rifles with almost identical use.

I forgot to mention that I already removed that as well.  The F/A is removed since I've used one exactly 2x for another rifle and I think it was an unnecessary amount of weight.  It's tempting to pull that one off that gun and just use a plug since the receiver is already cerakoted.

DPMS Slick side? dosnt come with those parts already, i think midway has them instock

The DPMS "Lo-Pro Slick Side" is actually a pretty heavy upper.  It's about 1.5x as thick as a standard A3/A4.  I used one in a 22lr build and that prick is heavy!

Today I emailed a MFG here in town and I'm sending my barrel to him for the contouring.  The Spike's .625 gas block arrived as well.

I'm about to get a Vortex SPARC on order as well and am planning on upgrading to an Aimpoint Micro at some point.

I'm looking forward to getting this gun running soon.

The barrel has been sent off to Accurate Armory for contouring.

The barrel's initial weight was 28oz.

The .750 gas block seat will go to .625 with about a .125" reveal forward of the gas seat and the rest of the barrel will be .600 with a .620 "flare" at the muzzle similar to a Daniel Defense pencil barrel.

Once the contouring is complete the forward half of the barrel will be Cerakoted Armorer Black.

The gas block was also left there for pinning to the barrel since it will be a heavy use gun and Keith recommended that it be pinned if it may see intense use.

I intend to

I'll weigh the barrel post contouring and I expect to see about a 4oz savings since it is 4150 steel and more than half of the barrel is getting turned down.  My Vortex SPARC is arriving Monday also.

I can almost see the complete gun my head now.  It should be a nice shooter.

I did take a photo show the contouring on the barrel before it went to Accurate Armory.

The Vortex SPARC that is currently on my 10.5" 762x39 SBR is going to transition to this rifle eventually.

I weighed the barrel prior to dropping it off and it was 28oz.

I'm expecting it any day now.

It's finally finished.

I got the barrel back from Accurate Armory today and got some weights measured on the barrel and all.

It came in at 28oz from Ballistic Advantage.  This included a .750 gas block seat and m4 contour.  I asked Keith at Accurate to contour it down to .625 for the gas block and once I saw it I knew it was going to be much nicer.  It now weighs 23.5oz so I was close on my estimate of 4oz saved.



The YHM 5.56 Brake was something I wanted to have on this gun since I have the .30cal brake on my Noveske 300BLK upper.  I don't think it's going to be needed to save the blast baffle of my YHM Ti 762 but it can't hurt.

I weighed the Noveske NSR 9 rail by itself and it came at an astounding weight of 5.5 ounces.  The barrel nut/screws were not included in this.


The barreled upper group minus BCG and CH also came in at 2lb 14.25 ounces.  The BCG and CH added 12.6 ounces.



Now for some photos of the finished rifle in it's completed state.  This was a fun build, and challenging myself to see where I could make that gun more practical without completely swiss-cheesing it.  I won't be skeletonizing any more magwells since it follows the rule of diminishing returns.  It came in at .25oz saved for all that extra work.  It does look pretty good though.

Very nice, what was the finished weight of the rifle?

99oz including the Micro.

Range Report here.