Parts list for an upper:
Barrel
Gas Block
Gas Tube
Forearm
Upper Receiver Assembly w/dust cover and forward assist
Carrier
Bolt
Firing pin and retaining pin
Charging handle
Am I missing anything?
Any recommendations on were to buy good quality parts.
most of the time you can get the whole bolt carrier with the firing pin, retaining pin and a .223 bolt for around 100 bux. Then just switch the grendel bolt in. I use mostly milspec overrun parts and have goodluck.
Grendel-Gene
Unregistered
From your list you are missing the pin that secures the gas tube to the gas block; a bolt cam pin; the bolt has to come with extractor, ejector and related springs, gas rings.... then a barrel nut... muzzle device and washer..... did you want a complete list of every little part?
Grendel-Gene
Unregistered
As for which brands to recommend, i like vltor stuff. Their MUR uppers are nice... i guess a lot of it depends on how much you want to spend.
Posts: 441
Threads: 11
Joined: Mar 2011
I posted a spreadsheet a couple of weeks ago with all the parts you need.
Many items come with the small parts. Or should, anyway. Ex: Gas tube should come with the roll pin. Flash hider should come with the washer. You can get the barrel nut complete with spring, etc.
Regarding bolt carriers: If you can use a spare 5.56 bolt your best bet is to get a for sure mil-spec M-16 setup like LMT or BCM. Or Colt. (yes, you can buy a complete BCG from colt)
If no need for a spare 5.56 bolt, then just get a GI contract complete BCG ($60'ish from G&R tactical), add the firing pin, bolt key, and cotter and the GRendel bolt that should come with your barrel. Not just supposedly "mil-spec", but for sure the real deal.
There are many BCG's sold as mil-spec that are not. They may have mil-spec staking on the carrier key, or claim mag particle testing on the bolt, etc. But the rest of the BCG is the wrong alloy, sub-standard coating, etc.
So I like using a contract M-16 carrier & key, then add the small, less critical parts from known sources. Grendel does better with the extra weight of the M-16 carrier, and it was what the AR was designed for. Most people don't realize the various "semi" bolt carriers have reduced contact surface, with the extreme being the old colt commercial AR-15 carriers. ("Half moon"). But even current semi carrier can be very different when compared side by side in both mass and bearing surface.
I do not care for the miracle coatied BCG's at crazy prices. I would consider a Young chromed BCG, but more for fit/finish than any magical quality.
Ultimately, the bolt is a more critical component and it will likely come with your barrel. It's more likely to have problems, wear out, or cause problems if wrong spec. So all the agonizing over the BCG will not make as much of a difference than the bolt will, as long as the BC has certain characteristics.
Pinz,
found and looked at your spreadsheet, very helpful, thanks
Gene,
no, I don't need every little part
question about receivers, billet 6061 vs. forged 7075 is the extra $40-$50 worth it, if so how, functionally, accuracy, strength, durability?
6061 is used by a lot of companies to ct costs on machine time and tool head replacement, since it is softer. It makes a great material for handguards and other parts, but I have a personal preference for 7075 T6 aluminum uppers, whether billet or forged. I also prefer 7075 lowers.
Posts: 441
Threads: 11
Joined: Mar 2011
There are volumes of debates on the various forums around 6061 vs 7075. To be clear, the spec is forged 7075 of a specific type (T6?). You can have 7075 and not be the correct spec. But most forged receivers in the last couple of years are of spec materials, and made to spec.
Likewise, there are 6061 grades that are comparable to the 7075 spec. There are also advantages & disadvantages to forged vs billet. Grain structure vs dimensional accuracy, etc.
The better billet CNC receivers are made from 6061 comparable in strength to the spec 7075. Certainly approaching the spec, to the point that you don't hear of billet receivers failing in duty. (There have been some failures from people force fitting parts with excessive force. This is strictly due to tighter tolerances on the billet)
Regarding strength of forgings, you have to also account for the fact that the billet material used in AR receivers is forged to make it a billet. so the only advantage the forged receiver has besides the material is any additional strength in the grain from the forging process, etc. It's not like the billet is "butter soft", or cast.
Realistically, Sundevil or better billet lower receivers have given excellent service. I use them on bench guns. For "hard use" guns (or at least those I would like to have hard use capable), I use a top tier mil-spec forged lower receiver. Not exotic, just a known quantity, for sure, mil-spec receiver (LMT, DD, Etc). Upper receivers it's a bit more difficult to find a "for sure" mil-spec in stripped form. After looking at many options for upper receivers, I came back to AA's deal. It's as good as any non-exotic, made from a quality forging, and excellent fit/finish.
There are volumes of debates on receiver material / mfg on other forums. I lean toward trusting some of the armorers with relatively high volume experience in Iraq on one of those forums. Their conclusion- most people worry way to much about lowers. And often spend too much on exotic lowers. Then go and put substandard components in far more critical roles (bolts, barrels, etc) Which do fail, make bigger difference, etc.
My learning from all this is that I used to build lowers and buy uppers. I now do the opposite. I can get a very good mil-spec lower assembled for not much more than I can build one. The uppers, I build with parts that I know the mfg & provenance, using as much "for-sure" milspec as I can.
I want:
- forged 7075 extension/buffer tube, mil-spec threads & dimensions
- Mil-spec lower receiver
- The best trigger group of the best mfg I can get. I'd consider Colt, LMT, or DD as the only standard trigger groups I'd use. DD can be had for the same as generics. There are other std triggers that are probably OK as well, but I go with known mfgs. I don't have as much experience with high end triggers, so won't comment on them.
Don't think there is a difference in trigger components? There are some pretty good side by side comparisons with Colt, LMT, DD, and then the generics. They are not the same! Nearly all vary, some are noticeably better than others in fit/finish.
I found LMT complete lowers provide the above at a reasonable cost. Not much more than I could build one for. DD used to, but they no longer sell assembled lowers. But would also use them or a Sabre one if available. Or one from a Colt 6920, etc. With the LMT you can also upgrade to a very good two stage for much lower cost than adding the same separately.
On uppers, most of my focus is on the barrel & bolt carrier
- specific barrels depending on caliber/usage. 4150 cold hammer forged if in 5.56 carbine. There are less hard duty options for Grendel, and more target options. So for my Grendel carbine I went with an SS M4 profile minus the M203 cuts on my most recent build. With a real Grendel chamber for reliability. Shoots pretty good for a carbine!
- Proper material & finish bolt carrier (8130 carpenter?? or something like that)
- Colt or military contract barrel nut
And I'm more likely to want different gas blocks, handguard/free float setups. So those I build the way I want them. But I'm more of a carbine guy of late. There are probably bench types who would have significantly different preferences.
OK, way more than you asked.
Hi guys, not to beat a dead horse, but in want to make sure I understand this correctly. You can take an entire 5.56 mil spec BCG and swap just the bolt for a Grendel bolt. You can still use the 5.56 firing pin and cam. Correct?
From what I understand, compared to a standard AR15, the only Grendel specific parts you really need are:
Barrel assembly with ramp
Just the bolt
Magazine
Muzzle device sized for 6.5
Perhaps some work with the buffer assembly
Maybe an adjustable gas block.
Reason I am asking, is because I am assembling the bolt before getting my barrel, since bolts have been the big log jam lately.
Yes, that's correct. The barrel extensions need to be done with more attention to detail as well, but that's largely out of your control.
The correct gas port diameter is more important and preferable over an adjustable gas block, balanced with an optimal recoil system for your charge and projectile weights.
customcutter
Unregistered
LRRPF52 Wrote:Yes, that's correct. The barrel extensions need to be done with more attention to detail as well, but that's largely out of your control.
The correct gas port diameter is more important and preferable over an adjustable gas block, balanced with an optimal recoil system for your charge and projectile weights.
I finally got lucky and got in on a group buy on the Liberty barrels. I was thinking of getting an adjustable gas block because of some of the issues I've read about over the years with cycling? What buffer/recoil system should I look at? Planning on starting another thread for my build but saw your post.
thanks,
CC
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