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Discussion Starter · #1 ·
I'm planning on building my first personal use AR in the comming 2005 year. I've had some experience with AR construction with friends ARs and I do home-gunsmithing on shotguns and bolt action rifles. This will be my first assault rifle project but I feel confident on building it myself and I trust myself to seek advice as needed. I anticipate going through the proper procedures for a class III liscence to make it fully automatic with a selector switch (safe/single/auto trigger group)and a stamp for a silencer. I also plan to use 30 rounders, an adjustable M4 type stock, and a rail system. Most definately a performance carbine setup, not a full M16 size and certainly not a CAR15 POS. However I am stuck bvetween two cartriges.

Enter, the 6.8 SPC and 6.5 Grendel

At first I was feeling really good about going with a 6.8 rig until recently when I heard the 6.5 may be even better, but I cannot find any conclusive proof to show any victor in the performance race. I am looking for the combination of consistent accuracy and terminal performance. I doubt I'll ever use the thing past 300 yards. 1.5 MOA @ 100 would be acceptable, 2 MOA would not be. I know Barret's 6.8 can perform 1 MOA out of their setup given to review at gunblast.com due to the reviewer's pictures. I have also heard that te Army is considering upping the M249 SAW to 6.5 Grendel in the near future due to the weight/performance tradeoff that it needs to stop these hajis on khat. If the 6.5 can perform even a small percent better than the 6.8 I will go with the Grendel.

Does anyone have any input backed up by established data that would put me in the right direction? Oh, and just for andy, I refuse to use 5.56. There, I said it, don't bug me. Also, having studdied the 6.8 I have learned that regular 5.56 AR mags usually jam when using 6.8 unless you only insert 25 rnds and that only the Barret mags are reliable. If I do use 6.5, should I buy up some 6.8 Mags or are regular 5.56 mags acceptable, remember I want 30 rnds no problems.

I know that its a finicky and picky request open to opinion and partisanship. Any info would be most appreciated. Thanks in advance.
 

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since you don't have a clue what it's for, much less how to actually go about it, go for it, waste your time and money.
 

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Discussion Starter · #3 ·
Why I can't afford to use 5.56

Sorry for the mock off comment there andy but let me explain why 5.56 will not work for me.

This weapon will be used for three things:
1) Competition
2) Fun
3) (and most important) Property defence (when we move)
4) Utility

I pray that the need never arises for #3. Yet, if it unfortunately did, and it was me/familly vs. someone with malicious intent on my property I would not want to need a follow up shot. Yes, im making it auto but why risk it? I do not want a solid kill to mandate between 3-6 shots in the vitals to drop some assailent. Even though I am a skilled marksman, why take the risk with an undersized over powered cartrige. (as the .223 would probly do a tiny bit better if it went slower, not causing over penetration) A 6-7 mm cartrige allows for 1 shot kills, even in non vital areas. I would never leave an assailent merely wounded, I dont need a lawsuit, the bigger cartrige with more kinetic energy would make sure kills so I dont get sued for "undo pain and suffering," which is usually what a 5.56 does, simply cause pain.

And away from the gim reality of things, I want a base to shove me off in the way ARs are headed in the years between 05-10. Most armys are constructing plans for a 6mm cartrige of some type, that includes the U.S.

I guess its important to read both of my posts to determine what im really after. Sorry for the "sad but true" part behind the project.
 

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I'd do 6.8 SPC, from people I've talked to, there's a good chance it'll be the new standard Military cartridge for the US military, going in the XM8. The 6.8 is also more compatable with the current, and prevelant, 5.56 AR15s. All you need to change are the bolt and barrel, current AR magazines will feed 6.8 (but magazines designed for the 6.8 will function more reliably). There are also more conversion kits from (5.56 to 6.8) and at least three new production rifles with chamberings for it.


The 6.5 Grendal is more powerful and fires a heavier and more stable bullet. The bullet also (supposedly) maintains supersonic speed until 1000-1200yds. The downside is that you need to change more components. I think you may even need a whole different upper because the cartridge is much fatter than the 5.56 or 6.8. The 6.5 Grendal is also more difficult to find than 6.8 (not that either are particularly easy to find). The 6.8 is (supposed) to be on store shelves, but I've never seen it. Also, if the military adopts the 6.8, or remains with the 5.56, it will fall away pretty quickly. The 6.5 is, as far as I know, coming out for AR15 type systems.

In summary, both are excellent cartridges for the AR15. The 6.5 Grendal is a better performer, but the 6.8 SPC was designed as a 5.56 replacement and is more or less compatible with all 5.56 systems, with the least number of changes to the base firearm.

**EDIT**

Due to the design of the Grendal cartridge, it may suffer feeding problems.
 

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Discussion Starter · #6 ·
:) Wonderful

Thank you very much 84 C4,, those posts had all the info I needed. I can see from the chart the 6.8 performs better until you use a much heavier load in the grendel. I can also see where feeding would be a problem. If you ever do need a hookup on 6.5 or 6.8 I know some good online places that sell boxes of 50 for 18$. I guess its time to start buying parts. My wallet feels thinner already......

Thanks 84
:uzi:
 

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Personally, I wouldn't choose a rifle or cartridge that hasn't been combat proven extensively! Call me old fashioned. Just my $0.02 worth.
 

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Discussion Starter · #9 ·
Stuck on the critical component

I've done some research, found a gunsmith who will correctly install the barrel, and even have one of my friends working on custom 6.8 mags, as the Barret ones are only actually 25 rnds (I just learned that, allow me to correct previous posts that said they were 30) and I want 30. I've also decided that at the current time, the paperwork involved in a class III dosent justify the output at the moment. I guess I'll make a 2nd lower in auto after next year, when it may be justified. And now that I have everything planned, I cannot find a dedicated 6.8 bolt carrier assembly. If Im not mistaken, 84 was looking for an assembly as well. Anyone know of a manufacturer that sells just the carrier, not a complete upper? If I got a 5.56 assembly could a machinest fine tune it to 6.8 spec?
 

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Of the two, I’d recommend the 6.8; right now both cartridges are “non-standard”, but if the military adopts the 6.8 as it looks like they may, it will become much less so.


That said, (yes, I’m going to bug you about the .223, but I’ll be polite about it…)

If using <=300 yards, I’d still lean toward the .223/5.56. There are a lot of very good loads out now for it, that weren’t available just a few years ago. Also, 5.56 suppressors, accessories, etc are a lot easier to come by. I’m not familiar enough with the 6.8 to compare, but I believe the 5.56 is a very under-estimated caliber by many.

FWIW, you may want to pose this question at www.AR15.com ; but be warned there’s a higher level of snobbery you’ll likely run into over there.
 

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Just because you are IGNORANT about what a 223 sp can do, and about what sort of hits guys get in combat, doesn't make the 223 not a fine round. It just makes you ignorant. Go for it, kid. waste a couple of thousand $ on your stupidity.
 

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Andy its an old point that you keep trying to make. You arent going to change anyones mind, so just drop it, ok?
 

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If I got a 5.56 assembly could a machinest fine tune it to 6.8 spec?
Theoretically it possible, stuff like that was common whenever a major army changed calibres. It depends alot on the machinists skill and how much "spare" metal you have. It might be more cost efficient to get a custom made barrel. Because the machinist will probably be using the same drill bits, and you'll still need to rifle the barrel.
When I was looking for a 6.8mm barrel for my friend's Mini14, I found a couple places online that would do it for around $300-$400, which isn't much more than a standard AR15 barrel. Then again, those were prices for a Mini14. Couldn't find a bolt, though. A 6.8mm bolt will be the most difficult component to find.
**EDIT**
I doubt he'd be able to remachine a 5.56 bolt into a 6.8. It sounds like it would weaken the bolt. I'd consult a gunsmith on where to remachine/buy a 6.8 bolt. If I find one, I'll tell you.
 

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Discussion Starter · #14 ·
Andy and his 5.56, Friendly Competition to End All?

Andy, When I'm done with my 6.8 project we can go out to a CAR1 and CAR2 course at SMTC and see who has the most skill. I'll even pretend the movers are actual hostiles for you and assume its a one shot kill. If your as good as you say you are, and your 5.56 is such a bad ass mo fo that it is not limited by a weapons ability to project it and that your M177 is the ultimate weapon system of all time, you will exceede my resuts on every test and qualification. If you dont want to do something that $$ and organised, pick a range, if I'm by your area, ill drop you a line, I have no problem meeting a challenge on your terms. Hell, If you want to setup concrete blocks and gel tests for a little excitement, that would be grand. And if you want to go on the system weight issue, we can always do a full field gear ruck race :dgrin: . Im sure theres a wooded area somewhere near your location. Mabye you even do have a point that no one notices, but I doubt it. But im giving you an open invitation to prove it. I have nothing personally against you as you havent annoyed me to a sufficient level yet, just put some documented proof and even some personal experience that is verified by some source behind your posts. Without it they are simply ramblings.

Just let me finish putting the sucker together. PM me if you accept my offer. Just know that the results of this friendly competition, should you choose to accept it, WILL BE POSTED. Same as if you decline. I think every one would love to know the results. And I am willing to do it entirely on your terms, even if their for some reason biased and partisan on your behalf.

The only reason I'm even taking the time on you is because it seems like a fun idea that would ammuse half the people that come to this site. I'm sure theres a competitive yet honest sportsman in you... somewhere. Hell, if I come that way I might as well take you to dinner at your favorite resteraunt, win or loose. Added incentive.. hehe.

Come on, Andy, whats to loose?
 
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