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I wouldn't want a SS barrel under a handguard where I couldn't wipe it down easily. They can rust. Nitride is a good option. At the least, I'd take the handguard off and coat it with Krylon.
You can put a lower together with tools most people already have, no problem. I'd buy an Aero stripped or populated lower and finish it out to my spec.
You can put an upper together with about $100 worth of tools. I'd build with BCM or Aero M4E1.
You will not necessarily save money putting your own together. If you object is best quality, it is more like reloading where you spend about the same to get exactly what you want, and the past time of putting it all together yourself.
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Alex984 Wrote:As for the upper, it seems like chamber spacing can be tricky. Maybe not?:
I don't know if tricky is the right word, but it can be difficult/inconvenient to check headspacing yourself since the necessary gauges aren't cheap. I could be wrong but it's also my perception that not many gunsmiths have headspace gauges for 6.5 G. I'm a DIY kind of guy and have built a handful of ARs, but this is why whenever possible I try to buy a barrel and bolt combo that the factory has checked for headspacing.
Other than headspacing being off, which is virtually unheard of when mating barrels and bolts from reputable vendors (but should still be confirmed), the only thing that you would need to be concerned about in that realm is that you buy the correct bolt for your chamber since there are 2 types of 6.5 G bolts with different bolt face depths. The standard by far is the "type II" bolt which has a .136" bolt face. But this is also hard to screw up since manufacturers and suppliers are mostly pretty good about making clear what type of chamber and bolt they are selling. If you're interested in learning about the chamber and bolt specs there are some good stickies above and the Horde will I'm sure be happy to answer any specific questions or concerns you have when making a purchasing decision.
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If a manufacturer follows mil spec for his barrels and bolts doesn't that mean headspace is correct?
I know about the .136" bolt face but didn't Colt establish specs for that so headspace would be correct?
My point is this is not some custom barrel job where headspace can vary depending on what the gunsmith decides..
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bj139 Wrote:If a manufacturer follows mil spec for his barrels and bolts doesn't that mean headspace is correct?
I know about the .136" bolt face but didn't Colt establish specs for that so headspace would be correct?
My point is this is not some custom barrel job where headspace can vary depending on what the gunsmith decides..
I'm not remotely an expert so feel free to correct me, but I'm not sure what you mean by "mil spec" because I don't think that term has any real meaning in the context of chamber or bolt dimensions. I take it you are referring to the parts being made within the correct tolerances, for example the barrel being manufactured with a saami spec chamber in such a way that the cartridge will be properly supported at the shoulder and base when used with a true .136" bolt. Opinions obviously vary widely on the necessity of checking head space since it is incredibly rare to have an issue when the barrel and bolt are from established manufacturers.
Nonetheless, barrels and bolts are made by humans using machines with parts subject to wear and misadjustment, so checking head space is nice insurance against the possibility that either the barrel or bolt is out of spec, or both are slightly out of spec such that the errors compound to create a problem. Personally, I'm not exactly religious about checking head space -- I just stuck some layers of masking tape on the back of 2 cartridges to make a poor man's no-go gauge to "check" my newest grendel upper -- but I do think it's prudent to check every barrel/bolt combo whenever possible.
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01-18-2018, 02:42 AM
(This post was last modified: 01-18-2018, 02:46 AM by VASCAR2.)
The 223/5.56 bolts use .125 bolt face +or- .001. When Colt designed and released an AR-15 chambered in 7.62X39 their research noted the difference in the rim thickness between 223/5.56 and X39 case. Colt Engineers used a .136 bolt face depth for the 7.62X39 cartridge. The deeper bolt face allows more room for the extractor for the larger X39 case. Bill Alexander looked at Colts design and saw the benefit of the .136 bolt and used it with 6.5 Grendel which is the same case head as the 7.62X39.
Recent manufactures of 7.62X39 AR-15’s did not use the .136 bolt face depth and went with the .125 bolt face depth used with 223/5.56 bolts.
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Dcommoncents Wrote:I'm not remotely an expert so feel free to correct me, but I'm not sure what you mean by "mil spec" because I don't think that term has any real meaning in the context of chamber or bolt dimensions. I take it you are referring to the parts being made within the correct tolerances, for example the barrel being manufactured with a saami spec chamber in such a way that the cartridge will be properly supported at the shoulder and base when used with a true .136" bolt. Opinions obviously vary widely on the necessity of checking head space since it is incredibly rare to have an issue when the barrel and bolt are from established manufacturers.
Nonetheless, barrels and bolts are made by humans using machines with parts subject to wear and misadjustment, so checking head space is nice insurance against the possibility that either the barrel or bolt is out of spec, or both are slightly out of spec such that the errors compound to create a problem. Personally, I'm not exactly religious about checking head space -- I just stuck some layers of masking tape on the back of 2 cartridges to make a poor man's no-go gauge to "check" my newest grendel upper -- but I do think it's prudent to check every barrel/bolt combo whenever possible.
Masking tape no-go gauge. I like it.
If the specification on parts is set by the military it is "mil spec".
I mentioned Colt set the spec to .136" for the bolt face because that's what I read here and elsewhere.
I don't think this is mil spec since the military did not adopt the Grendel. Maybe it is "Colt spec".
Most people buy the group buy bolt specified at .136" and buy a barrel with the same spec assemble it and shoot and everything works fine.
I don't think there is an epidemic of mil spec parts being out of spec. I think the manufacturers do a very good job.
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bj139 Wrote:Most people buy the group buy bolt specified at .136" and buy a barrel with the same spec assemble it and shoot and everything works fine.
I don't think there is an epidemic of mil spec parts being out of spec. I think the manufacturers do a very good job.
Agreed, it's largely a non issue. But I wouldn't feel comfortable suggesting someone NOT check headspace or buy a factory checked set because there is some risk however slight. I actually had a WMD bolt fail the no-go gauge in a ballistic advantage .223 wylde barrel, which is interesting because WMD's president said they use BA barrels, however not with a wylde chamber. Maybe it wouldn't be a problem, but I certainly don't use that bolt in that barrel (the bolt headspace was fine in my m4 contour 5.56 barrel though).
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bj139 Wrote:I mentioned Colt set the spec to .136" for the bolt face because that's what I read here and elsewhere.
I don't think this is mil spec since the military did not adopt the Grendel. Maybe it is "Colt spec".
And this is an interesting tidbit along with what Vascar posted. I think I also read about this design in one of the sticky threads but forgot about it. Smart move by colt and AA if you ask me.
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Looks like this has been fairly well hashed out, but I will reiterate that building your own lower is very simple, rewarding, and without doubt the most affordable option. About the trickiest part is the bolt catch. It's not that bad at all.
Recommend Aero Precision Gen 2 forged lower. Includes a couple nice improvements such as a second screw in the grip to remove any play between your upper and lower receiver, threaded rear takedown pin detent hole, and improved magwell. Can be had for as much as standard "milspec" forged lowers. Got mine for $40 on sale from Primary Arms, but you can search on sites like gun.deals
Personally, I also love Anderson "Sport" lightweight slickside upper receivers. No forward assist and dust cover. Two needless parts for anyone not deploying to the sandbox. Many still debate this hotly, but I have never ONCE missed these components. Think about... 9mm ARs are very popular now, almost always without forward assist and dust cover. No one seems to mind regarding those builds.
Regarding triggers, The ALG ACT is arguably the best duty style trigger. If you need that. If this gun will not be used for defensive purposes and marksmanship is the goal a drop in is the way to go. I like my POF straight 3.5 lb trigger myself. Only set me back $120 with KNS pins. Hard to beat. There are many good options now. Can't go wrong with Geisselle, but they are not the only quality option. POF, CMC, Elftmann, Hyperfire, etc etc
It is a fantastic market right now. I have no "need" for more rifles, but the deals I keep finding keep me building haha enjoy your new addiction!
