Can you guys share your opinion about advantages/disadvantages of each. - I'm not conserned about brass/reloading.
From 65grendel forum:
"I seriously looked at building a 6 PPC gun at least 3 times in the last 7 years or so. I was turned back by some very knowledgeable people including Scott Medesha. Two problems are brass and feeding.
Brass is usually made from .220 Russian, slow, and then it gets hell beat out of it in a gas gun compared to a nice single round feed tight neck bolt gun. Case prep for the AR requires full length sizing and some fair neck clearance for feeding. All this works the brass a bunch so it dies quicker.
Feeding the PPC has always seemed to be a problem peculiar to case length, shoulder angle, feed ramp position and angle, and magazine design. Nobody has gotten it consistently right.
The Grendel, through the patient work of it's creators, has solved all those problems. The brass will still get beat up, but at least it can be purchased. And since it's Lapua, ya can't go no better.
"Paul hit many of the points, but I would like to add a few.
The 6 PPC is an awesome cartridge, people building them in the past were hindered by a few key areas.
1. Use of .223 Rem / 5.56 NATO barrel extension - in simple terms, the feed ramp angles were all wrong. The Grendel utilizes a barrel extension with proper feed ramp angles. In addition, the shoulder area is smaller on the Grendel due to the 6.5mm caliber.
2. Attempting to make use of .223 Rem / 5.56 NATO magazines - The ribs used to space the smaller diameter cartridge did not allow proper double stacking of the larger diameter cartridge. Bill Alexander took the time to design the magazine for the Grendel from the get go,,, being a manufacturer has its benefits over one off custom guns.
3. Pressure and bolt thrust - the 6mm bore raises pressure levels as well as bolt thrust when people were seeking to push bullets like the Sierra 107 Matchking from the magazine. In 6.5mm, a Sierra 107 can reach the same velocity as a 6mm can, but at lower pressure, or at equal pressure will rung 200 fps faster due to a larger piston area at the base of the bullet.
Of course, one of the great advantage of the 6.5mm Grendel over a 6 PPC is bullet selection. With 6mm, you are pretty much done at 107 grains (exception for the limited 115 grain Sierra). In 6.5mm, you can go all the way up to 156 grains and down as low as 76 grains.