Darn. I got the nasty flu but this doesn't stop me for following up on my favorite threads.
After extensive testing with the Grendel I don't think that anyone will not able to push a 130gr bullet past 2550-2,600fps w/o ruining the cases no matter what barrel or powder.
The main reason I got the 6.5BR in for the AR15 was to improve precisely those kind of loads like the 130gr partition. It cannot be done with a short case other than a BR,
BRX or then a WSSM wildcat obviusly but those are a lot more involved specially for the AR15.
This doesn't mean the 6.5G/LBC is a bad round. It works really well with 100gr solids and bonded for hunting in similar way the 6.8SPC screams with 85gr-95gr solids.
For paper punching at long range works too but there are many others. Even the 6.5G simply necked down to 6mm is a significant improvement in long range ballistics over
the 6.5G parent w/o doing much. A really simple wildcat.
Like Llama bob said, the big issue in the Grendel and x39 with the AR is to make sure one finds reliable bolt groups that do not break.
It is only recently we are starting to see more ARs with strengthened beefed up bolts or dedicated bolts and extensions but there has been always the option to simply invest
in an AK, SKS or other carbine, ideally longer than 16" for better speeds.
The original Grendel numbers were a tad inflated by B.Alexander and that is what also gave some confusion and bit optimistic expectations. After a lot of chatter back and forth
these were adjusted and people now got to more realistic expectations.
I think everyone is doing the same thing trying to sell so there is always difference between the data from the marketing guys and the real life tests.
This is another reason what made the 6.8spc a very attractive and powerful option for the ranges people normally hunt. Reliability has not been an issue with the 6.8 and reloading
to the full potential yields very good performance not found in the milder factory ammo.
Again the 6.5G round is a substantial improvement in ballistics over the baseline. For some people this means they can shoot factory ammo and then use that brass if they want to reload hotter or more
specialized loads included the bolt action. For other people the drivers are a more affordable and plentiful round like the x39 including cheap steel and use the brass for some specialty loads.
Shooters who like to shoot somewhat flat (lets say the 2,700ish speed at the muzzle with .4'ish G1 ballistics) these are not the calibers although some reasonable compromises and something
interesting can be done with the 100 and 100gr solids. Also the x39 can put some nice momentum with 150gr bullets at moderate ranges. Something handy for larger game given speeds
do not fall too low.
The 6.5G is a nice round for what it is just like the x39. Interestingly both are also perfect donors for easy wildcats that provide substantial advantages over the original calibers
w/o investing a lot and obviously depending on the intended use or specialty. the 6mm-Grendel and the 35 gunner and good examples. There are a few others obviously.
But also in their original form they have a lot of nice options for people who like to research projectiles and loads and test everything.
Ballistics arguments can go on and on for hours and days as they are a fundamental part of our shooting culture and great entertainment over a camp fire.
But in the end, like any other science based on physics, in order to gain something we have to give up something. We can also throw in there popularity due
to marketing or earned merits, availability and costs.
In the ideal world I would love to have a round with the size, weight, recoil and cost of the 22LR and the performance of a win mag. But we know the world of ballistics and physics doesn't work
that way. The more you want the more you pay one way or another.