6.5 CM Build or Buy?

[Coffee_and_Pipes]

I’m looking at getting into shooting large-frame AR’s and would like some advice as to which direction I should go. I’m looking at something in 6.5 Creedmoor, but I’m open to .308. The rifle would spend most of its time at a 100 yd range, but I’d like something I could learn to shoot long range with, maybe try out PRS or something similar, and hunt deer-sized game with. It would be nice if the rifle were under 10 lbs. (dry).



If I bought a complete rifle, an SP10 would be at the top end of my budget. I’ve also considered a LaRue ulitmate upper with the thought of shooting it till the barrel went, and replace it with a Proof CF.



If I built, I’d like to go with the following list of parts:

•Seekins .308 Builder’s Kit

•Proof 22” or 24” CF barrel with +2 gas

tube

•SLR adjustable gas block

•JP HP bolt & bcg (LMOS or VMOS)

•JP silent captured spring

•Rifle length buffer tube

•Elftmann trigger

•Magpul PRS stock



If I went with the Seekins Builder’s Kit, I could buy two receiver sets so that I could build out a long range rifle, and later on, a .308 carbine. It seems like the advantages to building are that you can buy the exact parts you want the first time instead of buying a rifle and replacing parts. The downside would be that you don’t know if the parts are going to play nicely together.



I’d like to hear anyone’s experience if they’ve done a build with similar parts (any red flags?), or what everyone else’s thoughts are. Thanks in advance.

 

[flyer]

I built mine. It has a Criterion 24" bull barrel, standard length rifle gas, it runs fine with a JP BCG and SCS. I use a Syrac Ordnance adjustable gas block and get ejection about 8' away at 4:00.

I have heard of the +2" gas systems causing short stroking. I've had no problem with standard length rifle gas so I would go that way.

I haven't looked at that Seekins kit but if it's just receivers, I like the Aero M5E1 enhanced receivers with matching handguard. I have one and everything works and fits. The enhanced upper has a direct mounting for the free float handguard so it's not putting torque on the barrel nut. It's just a very robust way to do it, good looking, pretty light and the price is very competitive. Beyond the handguard mounting, it's pretty basic, without fancy ambidextrous controls but it just works.

For the barrel, four are on my radar but I look a little cheaper. First, Criterion makes very nice barrels with excellent accuracy and a pretty low price around $350 last I checked. I've heard some very good things about Wilson Combat barrels and they have made a lot of really nice 6.8 SPC barrels so I know they are serious about accuracy, when they go on sale you can get a 22" for about $250. I like ARP a lot but it's a small batch maker, availability is not always the greatest, price around $250. Finally, Brownells has a house brand barrel that is cheap if you have an FFL discount you can use.

The JP BCG I have is very nice but since then I've bought two Toolcraft nickel-boron BCGs and they seem really nice and so cheap it feels like stealing.

The SCS is nice and eliminates twang, I like it.

Add an Aero LPK, a nice drop in trigger and whatever you prefer in pistol grip and butt stock and you have a LR308 type rifle that will let you shoot 1,000 yards just about as easily as anything else.

A Proof barrel might save half a pound to a pound depending on the profile you're replacing but it seems kind of silly with that really heavy PRS stock.

I went with an Ace Ultralight stock so I just saved the weight on the other end, spent less on the barrel and spent less on the stock. I probably should have gone with a barrel lighter than a bull profile but it was all that was available when I bought it.

I could have saved maybe 1.5 pounds if I went with a CF barrel, lighter weight scope mounting and maybe a lighter bolt carrier. It would still be heavy.

 

[Coffee_and_Pipes]

Thanks, flyer. That’s a really helpful write up.

Since the 6.5 CM is a higher-pressure round, I’ve heard that a +2 gas tube is the way to go. Could it be possible that the person was running a buffer spring that was too heavy?

I’ve thought a little about an Aero matching upper and lower, but their price point had me wondering if they would have some wobble or play to them once assembled. That’s why I was leaning towards Seekins receivers. How tight do your Aero upper and lower fit together?

Thanks again for all the information. I really appreciate it.

 

[Triple D]

The Aero receivers have a tensioning screw. There’s no play.

 

[Triple D]

Oh, and you may want to add ballistic advantage as an option. It’s not a +2 gas, and is a heavy beast (they have a fluted version), but I’ve been happy with mine.

 

[flyer]

People keep saying that but I've used a DPMS rifle length buffer setup, JP SCS and a POF carbine buffer setup and they all take about the same effort to charge the bolt. One guy who had a POF that was running fine with the same buffer setup convinced himself that his spring was too stiff because of his gas setting.

When I see that many options with about that same tension, I have to believe that you would have to intentionally go looking for a super stiff spring to create a short stroking problem.

The +2" of gas system is really just -2" of dwell and less port pressure because it's further from the chamber. Maybe the gas port was drilled too small, I don't know. The gas system was the smoking gun. I'm not sure if or how it got resolved, I just don't see anything wrong with standard length rifle gas so +2" is a risk I wouldn't take.

Another "pressure" issue I've seen recently was pierced primers when shooting small primer brass with a firing pin designed for large rifle primers. I suggested trying large primer brass but that wasn't easy enough, he got a "high pressure" bolt with a small firing pin and swapped that out but without checking headspace as far as I can tell. That fix seemed to work but with the price of the bolt and the price of the Lapua brass he's going to be chewing up, it's going to be expensive.

About the Aero upper to lower fit, it's about what you expect from an AR but if you want it to lock up really tight, you can find some oversize and extended pins and get a little tiny adjustable reamer to make it a perfect fit.

The set I got is 0.050" longer than standard LR308 which makes it easier for my pudgy fingers to pop the pins past the detents. You don't have to get big knobs on the pins if you don't want to.

 

[KYAggie]

I could spend 30 min typing out my thoughts or just point you to this thread that's buried in here several pages back. Lots if food for thought in it. Also, Brownelles makes a titanium AR10 bolt carrier that is the least expensive one I've seen if you get on their email list and catch a 10% off sale. I have the JP enhanced HP bolt and use Starline SR brass with small rifle primers; no problems at all.

https://www.snipershide.com/shooting/threads/lightweight-2a-arms-xanthos-6-5-cm-build.6877340/

 

[Bigjake83]

Since you're new to Semi's I would recommend buying a budget Rifle like a RRA LAR 8 and just try to get used to the platform.

 

[flyer]

LAR8 seems to be a RRA proprietary design, it's not a good move.

 

[Bigjake83]

LAR8 seems to be a RRA proprietary design, it's not a good move.

Really!!!??

Just about every Large Frame AR is proprietary!

DPMS
Armalite
RRA
LaRue
Knights
Savage
LMT

They are all fucking proprietary!!
What... The RRA Mags are to tricky for you??

 

[flyer]

DPMS LR308 pattern is by far the most common type for parts availability.

As far as I can tell they have never stopped anyone from making compatible parts. Any LR 308 part can be bought from at least 3-4 suppliers, some parts like barrels are made by dozens of suppliers.

That's not happening with a LAR8. Even the "AR10" which really is only cosmetically related to the original AR10 doesn't have nearly as many compatible parts available.

It's a bad situation that has only got worse with the Savage flavor.

Telling people to try anything beside the LR308 (which is as good or better than any other flavor) is just encouraging the market fracture.

 

[Coffee_and_Pipes]

The Aero receivers have a tensioning screw. There’s no play.

Thanks, Triple D. I appreciate the feedback.

 

[AZgeek]

Nothing wrong with the LAR8. Shot them many times. Solid rifle except it does not have an adjustable gas block. But it does take FN magas which have worked flawlessly in my experience. Just built an AR10 based on the Aero Gen 2 upper and lower with a BA barrel. Very happy with the outcome!

 

[JimmyT]

Once you go Aero...u don’t go back.

I have an upper I built with an Aero upper, Lantac BCG, and BA 18”. Once you get the adjustable gas block tuned, they are rewarding to shoot at the range. My suppressor tames the recoil.

 

[Coffee_and_Pipes]

Oh, and you may want to add ballistic advantage as an option. It’s not a +2 gas, and is a heavy beast (they have a fluted version), but I’ve been happy with mine.

Thanks, Triple D. Your rifle sure looks like it shoots. Those are some nice groups.

 

[Coffee_and_Pipes]

Another "pressure" issue I've seen recently was pierced primers when shooting small primer brass with a firing pin designed for large rifle primers. I suggested trying large primer brass but that wasn't easy enough, he got a "high pressure" bolt with a small firing pin and swapped that out but without checking headspace as far as I can tell. That fix seemed to work but with the price of the bolt and the price of the Lapua brass he's going to be chewing up, it's going to be expensive.

It will probably be a few years until I can dedicate some space to reloading. Until then, I plan on shooting factory ammo. Do you know if factory is usually loaded with large rifle primers? I would assume so since the parent case was .30 cal.

Also, about pierced primers, I saw a thread on 65creedmoor where some guys were saying they found Federal primers to be softer than other brands:

http://www.65creedmoor.com/index.php?topic=940.0

 

[flyer]

As far as I know, all factory ammo uses large rifle primer brass. Small rifle primer is just a "Palma brass" thing with Lapua, Starline and other brass companies making reloading brass.

I guess Lapua could load their own cases but if a large firing pin can cause problems, I think they will leave it to the reloaders to load that brass.

 

[Coffee_and_Pipes]

I could spend 30 min typing out my thoughts or just point you to this thread that's buried in here several pages back. Lots if food for thought in it. Also, Brownelles makes a titanium AR10 bolt carrier that is the least expensive one I've seen if you get on their email list and catch a 10% off sale. I have the JP enhanced HP bolt and use Starline SR brass with small rifle primers; no problems at all.

https://www.snipershide.com/shooting/threads/lightweight-2a-arms-xanthos-6-5-cm-build.6877340/

Thanks, KYAggie. Your thread was really helpful to look through. How is your rifle shooting for you?

 

[awpk03s]

I put together one of the Larue Ultimate Upper kits. 22” 6.5 Creedmoor and purchased the Larue lower to go with it. The parts are certainly worth the cost. Mine is a nice rifle. I added a JP SCS Heavy, but the rest is as it came in the kit. I have shot a variety of factory ammunition with no issues or signs of pressure. It shoots Hornady 140gr American Gunner very well, and also Prime 130gr, and Federal American Eagle 140gr. I shot a long range steel match with it last weekend (my first time) and was very pleased.

My other built rifle is using an Aero M5 receiver set and enhanced upper/Handguard combo. It’s been mentioned here already, but the Handguard attachment method is a selling point of this, as is the attractive price point. Fit is tight. My only gripes are that I had to utilize an extended length mag release button to get it to work right, and the Handguard is really fat. I used JP SCS Heavy, Elftmann trigger, and a Faxon 18” Match Heavy Fluted barrel (rifle gas) with SLR adjustable block. Mated it all with Larue furniture kit (consistent with my other rifle). I have shot it once to zero it, and check for function/reliability, and was pleased. It liked all the ammo I fed it in 130/140 weights of Hornady, Federal, Prime. With the gas block turned in 10 clicks from fully open I had ejection at 4:00 and reliable lock back. The Faxon barrel chamber apparently needed additional cleaning and polishing from reviewing my brass marks - found similar posts here reporting same issue. I will address that and check the results next time I shoot it. I wasn’t necessarily shooting for groups, but the couple groups I tried printed under an inch at 100 yards.

 

[redneckbmxer24]

Large frames aren't like small frames. I'd buy the Seekins rifle and be done.

I've got a 20% off Seekins coupon you can have it you decide to go that route. It would be $2120 shipped to your dealer.

 

[KYAggie]

Coffee and Pipes, I'm very happy with how my rifle shoots. I have not had time since my boar hunt to shoot it, so I have not OCW tested any match reloads as if yet. I have 140 Nosler CC's and RDF's to play with and plan to use H4350. I'm glad my thread was informative; regardless of what weight bolt carrier and buffer you go with, get an adjustable gas block, they are worth it.

There seem to be several comments to the affect that AR10's are not like 15's in regards to parts compatiblity with suggestions to buy a complete rifle. Well, to some extent that is true and you need to be careful when making a purchase, but as far as parts go for building, most manufacturers of those parts build for DPMS pattern rifles and I had no problems getting the right parts the first time; it's not rocket science. If you want a light weight custom build, you will have to build it yourself or settle for something north of 7# in a production gun. Most production guns are north if 8.5# which ends up being a heavy beast once it has a 20 round mag and scope on it. Depends on your application if that weight is ok.

Obviously, I'm for building one, but the production guns recommended here have great reputations and are fine rifles, although heavy.

 

[Triple D]

Large frames aren't like small frames. I'd buy the Seekins rifle and be done.

I've got a 20% off Seekins coupon you can have it you decide to go that route. It would be $2120 shipped to your dealer.

You can get the SP-10 6.5creed for under 2050$ from some vendors when on sale.

 

[Coffee_and_Pipes]

I put together one of the Larue Ultimate Upper kits. 22” 6.5 Creedmoor and purchased the Larue lower to go with it. The parts are certainly worth the cost. Mine is a nice rifle. I added a JP SCS Heavy, but the rest is as it came in the kit. I have shot a variety of factory ammunition with no issues or signs of pressure. It shoots Hornady 140gr American Gunner very well, and also Prime 130gr, and Federal American Eagle 140gr. I shot a long range steel match with it last weekend (my first time) and was very pleased.

Thanks for the info, awpk03s. It's good to hear that your LaRue 6.5 CM has been working well for you. The more I think about it, the more I'm leaning toward going that route.

 

[Coffee_and_Pipes]

Large frames aren't like small frames. I'd buy the Seekins rifle and be done.

I've got a 20% off Seekins coupon you can have it you decide to go that route. It would be $2120 shipped to your dealer.

You can get the SP-10 6.5creed for under 2050$ from some vendors when on sale.

Those SP-10's really seem like solid rifles, but if I go that route, I'll be limited to one rifle. I'm leaning towards a couple of Larue UU's (one 6.5 CM and one .308 carbine), and then upgrading parts as I go. Thanks for all of your advice.

 

[Coffee_and_Pipes]

Coffee and Pipes, I'm very happy with how my rifle shoots. I have not had time since my boar hunt to shoot it, so I have not OCW tested any match reloads as if yet. I have 140 Nosler CC's and RDF's to play with and plan to use H4350. I'm glad my thread was informative; regardless of what weight bolt carrier and buffer you go with, get an adjustable gas block, they are worth it.

There seem to be several comments to the affect that AR10's are not like 15's in regards to parts compatiblity with suggestions to buy a complete rifle. Well, to some extent that is true and you need to be careful when making a purchase, but as far as parts go for building, most manufacturers of those parts build for DPMS pattern rifles and I had no problems getting the right parts the first time; it's not rocket science. If you want a light weight custom build, you will have to build it yourself or settle for something north of 7# in a production gun. Most production guns are north if 8.5# which ends up being a heavy beast once it has a 20 round mag and scope on it. Depends on your application if that weight is ok.

Obviously, I'm for building one, but the production guns recommended here have great reputations and are fine rifles, although heavy.

Thanks, KYAggie. The more I think about it, the more I'm leaning toward a couple of LaRue UU's in order to have a couple of rifles that work from the start, and then see about picking up a receiver set on sale to play around with down the road.

 

[flyer]

The way to do it is mostly Aero parts with a better barrel, trigger and furniture to suit.