Why 6.8 instead of 6.5?

[panzerr]

I've seen a lot of garbage issued by the Army, so i don't take stock in 'if the military uses it, it must be good'. When i see data that says one product is better than another and I don't see the better product in production I wonder, "why the hell not?" Marketing aside, there are sometimes legit reasons the public doesn't realize for one product being more common than the other. Sometimes not. Thank you for shedding some light on the subject.

[rob_s]

When i see data that says one product is better than another

Somewhat off-topic, but I'd be wary of proclaining one thing better than another off of one single-page pdf of unknown origin. and I know you know this, but "better" for one person may not fit another person's needs.

[Sevcrist]

While I can agree that the 6.5 Grendel is "better" at long range, there are other variables involved as alluded to earlier. Is the Grendel better than the 6.8 for durability and longevity of the barrel, bolt and other components? Does it feed as reliably as the 6.8? Does it have as good or better than penetration characteristics? Etc., etc.

[Gunpowder]

I think that's a great point because it appears they are both great products. I say appears because I only own the Grendel and haven't shot it enough to offer any authoritative statements. It looks like its going to do the job I bought it for. Nothing tactical, just whitetail and yotes near and far. There are plenty of better rounds for the job but none that fit in a AR-15. For me that includes the 6.8 and I base that statement on bullet selection only. To me they are basically equal other wise. Just one man's opinion.

When it comes to Alexander Arms and the Grendels future, I can't tell if their slowly growing or fading away.

[mark5pt56]

Maybe I'm taking the bait here but...Apple does put out a great machine and is gaining market share all the time. As long as you don't compare the 6.8 to Vista, that would be low.

I think that's a great point because it appears they are both great products. I say appears because I only own the Grendel and haven't shot it enough to offer any authoritative statements. It looks like its going to do the job I bought it for. Nothing tactical, just whitetail and yotes near and far. There are plenty of better rounds for the job but none that fit in a AR-15. For me that includes the 6.8 and I base that statement on bullet selection only. To me they are basically equal other wise. Just one man's opinion.

When it comes to Alexander Arms and the Grendels future, I can't tell if their slowly growing or fading away.

Based on my non scientific obserservations over the last 3-4 years--colorfast bleach should've been used on that load.

[motorwerks]

My answer is simple......

go to your local gun store and try and buy a box of each. At least locally you cant find 6.5 anyplace but my walmart has a box f 6.8 once in a while.

[Suwannee Tim]

You can, using careful mathematical calculations prove that 6.8 mm is superior to 6.5 mm. You can change the assumptions slightly and prove 6.5 mm is superior to 6.8 mm. One fact, there are a number of long, slippery bullets available for 6.5 mm and comparable bullets can't be had for .257 or .277 (6.8).

[500grains]

The point is proprietary / licensing vs. put out for everyone to use. Microsoft put theirs out for everyone to use and immediately they dominated the market, in contrast to Apple who kept their OS proprietary and had a very small market share. It seems that the 6.5 Grendel is following the Apple model with the early years Apple results.

If the 6.5 Grendel would push a 120 grain bullet to 2800 fps out of a 16 inch barrel, or a 140 grain bullet to 2600 fps out of a 16 inch barrel, I would get one. But I am not fooled by hopeful numbers from a 24 inch barrel, because there is no way in heck I am carting around a monster 24 inch barrel on an AR15. I would much rather just carry an AR10.

[LockenLoad]

it doesn't make sense to me that a cartridge would be supported by the industry and a small portion of the military over a similar cartridge with superior performance so I was asking for some reasoning behind the madness.

What I'm gathering is that, in essence, the reason 6.8 rifles are more prevalent is due to the fact that 6.5 would cost a few bucks extra for companies to produce since AA owns the rights to the 6.5 design.

I thought most of what I have read, is the 6.8 is better out of SBR's, but I could be wrong the 6.5 excelling in the long range roll more.

[Bubba FAL]

"Clear superiority", eh? Superiority at what?

As others have mentioned, one should be very careful reaching such a decisive conclusion based upon one ballistics chart on one website. Especially if the 6.8 data is pre-SPCII era.

The two cartridges are very closely matched over most of their capabilities. It is only at the outside edges of performance where there is any significant difference.

For example, the 6.8 does not gain much velocity in barrels greater than 18-20". The 6.5 can take advantage of barrels up to 24". Conversely, the 6.8 loses less velocity out of short barrels than the 6.5 (this is a factor of the burn rate of the powders generally used in the respective cartridges for proper pressure curve in the AR15 platform).

As to inherent accuracy - any difference exhibited is the result of differences in firearms, not difference in capability of the cartridges. Generally, due to the high BC bullets available for the 6.5, trajectory is flatter, making it easier to hit at long range, but this is not important for most shooters as most will never fire a round beyond 200yds, let alone 600+.

So, it all comes down to what the end user desires. For some, the 6.8 is superior because it meets their needs. For others, it's the 6.5...