Kicking around the idea of building an upper for precision work. I already have a custom built 6.5 Creedmoor bolt-action for Tactical Matches but would like something else to maybe shoot some matches with. So far I have already considered .223 Remington, 6 PPC, and 6.5 Grendel. Grendel is favored so far. What else should I consider?

Whether you go with a 6mm or 6.5mm, just remember:
- You CAN'T push an auto-loader as hard as you can a bolt gun. If you do, you will be trashing your brass, and you can run into reliability issues with failures to extract/eject.
- Make sure that your build has a good adjustable gas block, you will only want to run as much gas through the system as you need in order to save your brass and insure reliability.
- You will be limited to mag length loads, so make sure that your round/load will work well with a Factory/Mag Length OAL.
- Given you will be running mag length rounds, consider that when you have the barrel chambered/throated (most autos will have very long throats), and pick a bullet that is jump tolerant.

I have run both a .260 and .308 auto-loader, and I learned most of the above the hard way!

Whatever you are looking at, make sure that you can get the components to reload. There are a number of rounds right now that it is next to impossible to find brass for. Also consider the cost of the reloading components, especially the brass. No matter what you do, most auto-loaders will trash brass fairly quickly, and full length sizing it every time will also wear it out quicker. It sucks to have a rifle that you can't shoot because you can't find what you need, or you can't afford to pull the trigger!

You can argue ballistics all day long, and there are a lot of rounds that will work well in auto-loader for long range. As long as you look at everything, and have a thorough objective decision making process, you should end up with what you ultimately need. Don't just let popular internet opinion make that decision for you!

If you have specific questions or concerns, fire away and I am sure someone here can help you out.

Best of Luck,
M Richardson

EDIT - you are asking a very open ended question at this point, so you will need to narrow it down, if you really want good feedback. Going from a .223 to a 6 PPC, is like going from a Ford to a Ferrari. You are going to have to nail down things like:
-Application
-Range(s)
-Custom or Factory
-Budget

I'm just comparing AR-15 Precision Long Range cartridges for now. Once I nail down the cartridge I'll be looking to decide on barrel length and twist.

This will be a scratch built upper, I already have a lower it will go on. Budget isn't a concern... buy once, cry once.

For competition the max range I would shoot it would be 700 yards. It's not a requirement but I might possibly go out to 1k just playing around.

Some of the local tactical match guys shoot .223 bolt guns out to 700 really well. I imagine they push them pretty hard though.

6PPC was only considered because my brother in law is also interested in it. From what I have read though it seems they may not be that reliable feeding and the brass selection may lack.

For 6.5 Grendel it seems the brass selection is good. I know the bullet selection is good. And there is quite a bit of off the shelf ammo available if needed. Sounds like the performance is what I need also.

But what else should I look into?

6mm Hagar. IIRC, Carl Bernosky used it in the first semiauto to win the National High Power Championship a few years ago. Like mentioned already, brass availability may be an issue.

Sorry, I had originally missed that this was strictly going to be an AR15 platform (versus possible AR10).

6mm Hagar, the issue is running heavy bullets in a mag length load which kills the case capacity. As such if you are going to mag feed, you are pretty much stuck with small/light bullets.
http://bulletin.accurateshooter.com/tag/6mm-hagar/


6mmAR, probably the best option if you want to sling the 6mm bullets.
http://www.6mmbr.com/gunweek068.html


6.5 Grendal, if you can live the availability issues associated with them, it is probably the best option if you prefer to sling the 6.5mm bullets
http://www.6mmbr.com/65grendel.html


The 6mm vs 6.5mm is a very hotly contested debate. If you want to follow the trends with the PRS, the 6mm is winning the battle, but also bear in mind that is with .30 cal based rounds.

Per my comments above, IMHO you will have to look at all of the factors to come up with your best option, I don't think that there is going to be one overwhelming absolute answer.

Sorry for not nailing it down further, but hopefully you can start to work through the process as to what will ultimately work best for you.
M Richardson

I sort of want a 6mm AR Turbo

If you don't mind a wildcat check I to the 5.68dmr. It is a 6.8spc case necked down to .224 with the shoulder pushed back. Using 6.8 mags it will seat 90 grain bullets to magazine length, and push them to 2900fps. Mod ahay from snipershide is working on this project. At his elevation he posted some numbers that show this cartridge to be viable past 1200 yards. With the 90 berger vld it was supersonic past 1400 yards,  I believe he said it transitions at 1510 yards. All these numbers were from his location, IIRC his elevation was 5200 asl.

If your interested you could try contacting mod ahay on snipershide,  or contact Youngs manufacturing. This sounds like a great long range round for the ar 15th platform.

That's a really interesting sounding cartridge!

Sounds like a fun wildcat. Really wish I had the time and range to work on something like that.

Per what is listed here, there are a number of options out there, at some point the devil will be in the details!

What matters the most?
- Factory of Custom
- Availability of Upper Components
- Availability of Reloading Components
- Budget: Cost of the Upper, Cost Per Round
- Ballistics: Internal, External, and Terminal
- Application: Hunting, Targets, Defensive
- Barrel Life
- Recoil

Every round listed above has both Pros & Cons, and you will get different answers to the topics listed above.

You are now going to have to figure out what will work the best for you given situation. If you have more specific questions, fire away.

Thanks,
M Richardson

Wildcats sound great on paper, they aren't as much fun to live with day in day out. .223 is a very accurate cartridge that is easy to reload, find brass in quantity at a reasonable price and it is totally reliable. You won't need custom bolts or magazines either. 69 grain to 77 grain match bullets makes this round rock. I would suggest building a premium .223 Wylde upper and using match grade bullets.

Of the specialty rounds 6.5 Grendel is the only real option, not because it's the best, but because it is mainstream. 123 grain match bullets feed and function from Grendel magazines. 6mm wildcats limit you to 87 grain Hornady hpbt match bullets. Anything heavier can only be loaded long and fed directly into the chamber one bullet at a time. This destroys the semi-auto ability of your rifle when using the best long range bullets.

I have two 6mmWOA spaceguns and they are very accurate. 95 grain and 107 grain 6mm Sierra Match Kings must be loaded longer than magazine length for use at long range. 6mmHagar suffers the same problem. 6mmWOA and 6mmHagar are very close to each other in performance. I can get 107 grain SMK's up to 2750 fps from a 26" barrel.

Visit Robert Whitley's "6mmAR" website. He offers a host of custom AR15 chamberings and knows more about getting them running then anyone else around. Be advised that he sets his rifles up for NRA match rifle competition and 26" barrels are the norm. There are two reasons for this, it's required for gaining maximum velocity from these underpowered rounds so they can compete at distance and increasing sight radius for better focus and finer sight adjustment.

For what it's worth I load 107 grain 6.5mm Sierra Match Kings in my 18" 6.5 Grendel and get amazing accuracy @ 2600 fps. The B.C. is nearly identical to M80 7.62x51mm  ball ammo and only 150 fps slower. They don't "fly" as well as 107 grain 6mm's, but they are impressively accurate at closer ranges.

Try 77gr bthp match ammunition if you 5.56 upper is a fast twist barrel.

Not really much reason to kid around with the big rebated ctgs if you have a precision match-quality 5.56.

Came to the same conclusion for the AR-10 platform.  .308win with match bthp is the ticket.  Maybe you go .260rem
or 6mmXC for a  bit higher BC, but are you competing or looking for all-around accuracy w/o reinventing the wheel?

Got match loading gear?   Know the case prep and gauging techniques?  Comes down to tailoring for YOUR Chamber.
Got a min oal chamber?  Run only your handloads and all is well and you're looking at benchrest precision; your rifle
will deliver the goods.

surprise no one said the .277 wolverine.... its a 5.56 case with a 6.8mm bullet.

packs about the same punch as the 6.8 spc

The 6mm Fat Rat is intriguing when considering the AR-15 platform. It is based on the Grendel case, but allows for better velocities with some of the heavier projectiles.  Info can be found here (as well as elsewhere...)

http://www.accurateandreliablerifle.com/products.html

Mind you, I have zero personal experience with it, but I was looking at it when considering the chambering of my last AR build.  As it turns out, I'm boring...stuck with the good ol' Wylde chamber.

A local guy showed me his 22/6.8 wildcat.  It's simple to make brass (1 step through FL size, load & shoot).  He showed me this data from his testing today. If you load it may be a contender.


http://mbd.scout.com/mb.aspx?s=541&f=5515&t=13339872&p=1&sto=MS_164109975

I had a gun in 6mmAR and it was great. As far as powder capacity goes in anything that you can fit into an AR15 platform and feed from a magazine the 6mm bullet is definitely the ideal bullet for the best external ballistics. In a 24" barrel I was pushing 105 Hornady HPBT bullets to 2770fps with no trouble, and the rounds had no trouble fitting into 6.5 Grendel mags. I know there are other rounds that go a little faster if you fireform or whatnot but I just wanted something that I could size initially and then be off and running, so the 6AR was an easy choice. I didn't shoot it much before selling it and building a 6XC AR10 gun, but I shot a match with it and took a long range class with a friend and those little 105s at 2770 are pretty nice.



Pulled one


The ammo even looks cool