Ive been absent here for some time and haven't been too active with building, shooting or studying guns in general lately. A friend is wanting my help with a 308 build. He wants accuracy to be the main, if not only concern.

Yes, he is stuck on it being 308. Yes he is set on building it and not buying complete. Money isn't an issue. Yes he understands a rifle will only be as accurate as he is. (I think that covers most of your initial questions or sarcastic remarks)

Ive only built AR-15s, never a 308 and Ive only built lower halfs, never the upper too. So please excuse my ignorance. Also the information I have is at least 2 years old, so if I mention a brand thats outdated or no longer arfcom cool, again please excuse my ignorance.

Here are my thoughts so far:

Mega Arms billet lower (he already has the upper)

Timney or Geissele trigger (I have no idea which one of these though, I know they offer multiple options)

The barrel brand and length is where Im really stumped. I think Im settled on a 20" barrel but not sure. I can't remember the best or most accurate custom barrels out there. Also, no clue on if it should be fluted, or threaded or anything


Any help or opinions would be very appreciated.

You can get some really great deals on ballistic advantage barrels if you are willing to shop around. Both Schuyler arms and monmouth reloading had some great deals on ballistic advantage products (they are now owned by aero precision). Really depends on what you are hoping to do with the rifle for length and profile. I would try to get a rifle length gas system and I would go with 18" or 20" in length. Snother great option is fulton armory barrels, I have the SS 20" barrel m110 profile and it is pretty impressive easily 1 MOA or better when I do my part and use decent ammo. Another great option is Ranier arms barrels. At all levels, select, match, and ultramatch they are great barrels but it will require you to flush out your stated purpose for the rifle and know your load.

Types of rifling and twist rates that are optimal will be determined by what type of ammo you will use. BTW both ranier arms and fulton armory will headspace a bolt to a barrel if you buy them both together. Although, if price is no object you could send a bolt off to someone like shilen or criterion and have them cut the barrel to the exact dimensions to match the bolt you plan on using.  Depends on how far you want to take it, or what you consider good enough.

You should look at criterion website for recommendation on flutes, they are good for weight reduction, but simply put rigid barrels are accurate. Its a balance between weight and portability vs. ultimate accuracy. However, plenty of medium profile barrels with amazing groups. Even some lightweight profile barrels come with 1 moa or better guarantees. You should layout the types of shooting, environment, ammunition types, and such to assist with recommendations.

Jared I'd love to help you out here but first I've gotta ask, why the initial comment about coverring all of our smart remarks while asking for our help?

You can copy mine if you want.  

Receiver:
Mega Maten ambi. set

Upper components:
Mega 20" barrel
Aim nitride 308 BCG
Mega charging handle (soon to be replaced by a BCM gunfighter mod.3)
SLR Sentry 7 adjustable gas block
Spikes Tactical rifle-length melonited gas tube
Fortis 15" 308 switch rail
Larue index clips (upper rail)
BCM keymod rail panels (sides and bottom)
JP large-profile compensator (1.2" to .750") w/Gemtech shim kit (5/8-24)
Troy folding battlesights (M4 front, standard rear)
Primary Weapons keymod bipod adapter
Harris 9-13" S-series bipod

Lower components:
Geissele hi-speed national match (match rifle) trigger
BAD-CASS safety lever
Spikes Tactical billet magazine release button
Magpul PRS stock w/extended butt-pad (0.80")
DPMS A2 receiver extension
JP silent captured spring w/lightest spring (from builder kit)
Magpul Moe+ grip
Magpul M3 10rd Pmag

Optic:
Vortex Viper PST 6-24X50 FFP w/EBR-2C MOA reticle
Bobro dual lever 30mm precision mount w/20MOA cant
Vortex 30mm bubble level
Vortex SV-2 Switchview throw lever
Butler Creek flip covers (14 and 43)
Tenebraex Sunguard ARD

It was a joke for the most part. You're still pretty new here, but a lot of times the first few commenters will post something sarcastic. But I forgot I didnt post this in general, so probably won't get that as much.




Whats the MOA you've been getting, on average? It looks great for sure.

With 175gr. FGMM it's shooting 0.7 MOA without even trying.

I need to try some 168gr. to see what the barrel prefers.

Now that it's cooling off here in north Texas, I'll start developing some handloads.

Essentially a .308 18" JP rifle except for the receiver set.

Have not dialed it in yet, so I can't comment as to accuracy yet.

Receiver is the Mega Nickel Boron set? Which barrel did you choose? I think I am swaying towards this one JP 20"

How do you like the barrel heat dissipator thing?

The same one I linked in your other thread.  18" JP w/ bolt, gas block, gas tube and muzzle break.  The receiver set is an NiB set from Sun Devil that I had for little while before the build.

Aesthetically, I think it looks pretty cool with the contrasting blue anodization.  Functionally, I havent put enough rounds though it (only enough to function test it) to realize it's intended benefit.  To be honest, it was a cosmetic attraction rationalized as practical application.

I think it looks pretty damn cool too.

Fair enough Jared.

What's you're buddy doing with the gun bench, hunting, other? What kind of total weight of this thing he ok with? You'll want to nail down where he stands on the weight before picking a barrel and stock. I see he has a Maten lower do you have plans for the rail/handguard, yet are you going with one from Mega here or? How far out does he wish to run the rifle? What are his plans for ammo, factory, or does he reload?

If price is not important and he wants the best parts, on some the internals of the rifle, I'd check out the JP LMOS BCG w/HP bolt. JP's high pressure bolts do help with the elevated pressures in the AR10 platform and the low mass bcg's reduce recoil by lowering the cycling mass. I could be wrong but I think you need an adjustable gas block if going with this bcg check out Syrac, and SLR rifleworks for this. You can also pick up a melonited gas tube from SLR.  Also a geissele trigger would seem to fit the bill I would suggest one of the National Match triggers I have the DMR version and its very a nice trigger. On the brake I have APA little basterds on both of my precision rifles, love em. I do own a JP brake as well though and can't tell any difference in recoil, so its mostly aesthetics but I do like that the nut to remove/install the brake on the APA is much larger than the JP, makes it easier. Of corse there's other high quality parts out there but these are what I chose, and I'm certain they will not disappoint.

I just finished a Maten build in 6.5CM I'll drop a pic if you wanted to see what the parts look like together. This is a 22"
Krieger w/heavier profile offered its 1/4moa with factory hornady, SWS 13.9" rail, PRS stock, Schmidt and Bender 3-27. I've already talked about most of the other parts. Now again back to the weight it doesn't bother me because I knew going about in where I was going to wind up but this is a 16lb rifle as you see it.

Its going to be bench/target shooting only and he wants it to be as accurate as possible. He hopes to be able to take it out to 1000 yards. So all these things considered, weight really isn't an issue, as long as its light enough to carry from his truck to the bench ;)

I would look at another caliber if you want to shoot at 1000yds.

.308 will get there all day long, just not as predictably as I prefer, and the danger space is horrendous, especially when you watch it through the spotting scope or print it through 2 layers of soft target.

You'd be surprised at what kind of angle it is coming down at.

Get 6.5 Creedmoor or .260 Remington instead.

I chose 308... even if it is tracing a large arc. .

I'll take the extra barrel life at the expense of one or two tenths of MOA.

So you haven't picked a rail yet then?  Or the type of upper from mega?

With the 308 out to 1, 000 is possible but you're really maxed out with that caliber at that range, and you're going to be best off using some of the 175 grain ammo for that. If memory serves me I believe you'll want a 1/11 twist for that and if it were me I'd opt for a 24" to give a little extra velocity and give that 308 all the help it can get. I'm aware you're buddy is set on 308 but if he is unfamiliar with and unaware of the capabilities of the 6.5 creedmoor cartridge he would be well advised to take a hard look at it. Very similar cost of building and cost of ammo but a large performance gain, however I don't want to push in a direction you don't want to go.

On the twist rate I'd call the barrel manufacturer and get advised directly from them vs taking some internet advice. Also its a good idea to build the gun around the intended ammo. I can't really say too much more without having an idea of what ammo is going to he running though this thing which is why I've asked you about ammo already so again does your buddy relaod? Will he be shooting reloads/ factory ammo exclusively?  If you're looking at running factory ammo but don't know were to go I would have a look at federal gold metal match 175 grain SMK. It were me and I were building a 308 to shoot factory ammo out to 1, 000 I would build the rifle around that load particularly. Also of much importance for reaching the 1, 000 goal, what is your altitude? ??

Performance advantage of the 6.5s over .308 at 1000yds is far more than you currently understand, even better than a 190gr SMK from the .300 Win Mag.

My 130gr VLD load at 1000yds from .260 Rem at sea level is 8.6/29.7 mils drop, 2 mils drift with 10mph wind.

A .308 175gr BTHP at 1000yds from the same barrel length is 12.5 mils/43 MOA drop, 3 mils drift in same conditions.

Your hit probability with a .308 at 1000yds is extremely low, even with corrections.

When you do hit steel, it often looks like a miss because the bullet is coming down at such a high angle, that it deflects off the plate without spalling, and kicks up dirt in front of the target like a miss would, so it can be difficult to register unless you shoot massive gongs at 1000yds.  I shoot reduced sils at 1000yds, because 1000yds is actually kinda boring with the 6.5mm, but it flies straight to the target, not down at it like a .308 does.

There's a reason why I sold all my .308 components, dies, and rifles.  I chased that cat with several 24" and 22" .308s, and the juice was nowhere near worth the squeeze, especially when you look at the rifle weight and recoil.

The only place .30 bores make sense are in magnums, and the 7mm will still smoke it all day long from the larger cases, especially the 195gr Berger EOL, which beats the 230gr Berger .30s and 250gr .338s even.

The OP said his dad wants to shoot at 1000yds.  My experience over the years chasing 1000yds with .308 is that you have a very frustrating time at the range, whereas with 6.5mm, you have a sh*t-eating grin on your face the whole time, and see 1000yds as not much of a challenge, looking for longer distances to stretch its legs at.  The .260 Rem is still supersonic past 1400yds at sea level with my 130gr load.  It is extremely flat at 1000yds, much more than I would have ever thought after years of watching .308 mortar-like performance.