King of the Grendel round count

[LRRPF52]

On the 10.5, I'm gonna assume you have already run this or gone over the ballistics in details vs 11.5 and 12.5? Which would you say ballistically is the sweet spot, for a dude like me that'll probably only have one 6.5G pistol?

I'd been hearing 12.5 but not necessarily stuck on that length either. I don't "need" super short, but yeah short is handy if it's only a small ballistic trade-off.

Ballistic sweet spot is the longest barrel you can get for the maximum mv that the case capacity will support.

Most compact is the shortest you can go and still have a reliable firearm.

A balance between the two meets somewhere in the middle.

I got the 10.5” so my kids can shoot something that is more friendly for them when looking at weight/balance, as well as doing some practical field-testing to see what it will do on-target and at distance.

With 123gr, a lot of the data I’ve seen puts 10.5” in the 2200fps region for mv.

With the 120gr Federal Match load from my 12”, it does 2384fps 15ft from the muzzle average.

That would be 2330fps from the 10.5”.

If a 123gr SST does 2300fps from a 12”, then it would do 2233fps (2183-2282fps) from a 10.5”.

For hunting with the 123gr SST, that would give me a very practical PBZ using a 200yd zero, and plenty of effective range (I’m using a more realistic and lower G1 BC of .462, not .510:

0___2233fps 1362 ft-lbs -2.5"
50__2146fps 1257 ft-lbs 1” high
100 2060fps 1159 ft-lbs 3” high
150 1977fps 1068 ft-lbs 2.5” high
200 1896fps 982 ft-lbs ZERO
250 1817fps 902 ft-lbs -5” drop

That exceeds the performance of a 16.3” AK (shooting the same bullet weight at 2350fps) at 100yds, then continues to run away from the AK from thereon out, with 400 more yards of supersonic reach.

The 10.5” Grendel shooting a 123gr at 2233fps has 112 more ft-lbs of energy at the muzzle than a 20” .223 Rem has shooting 55gr at 3200fps, and just walks away from it as well.

For target work, the 107gr SMK will do 2319-2412fps (barrel dependent) on the max load of 8208XBR, which even when compressed, is still at 49,300psi chamber pressure.

That should make a fun little blaster for the kids to shoot steel with.

Using the G7 drag model at 2400fps and the lowest elevation I can shoot in my State, that still puts it supersonic to 1000yds. Enters transonic at 800yds.

6 mils of drop with 1.6 drift at 650yds