Getting there with 100gr A-Max

[Blacklab]

Wasn't getting the groups like I should with AA upper and 18inch barrel. I returned the barrel to AA for a chamber check. They returned it saying all is good. So now I know it's me and my build Put it all together very carefully making sure all is square. This Is what I got first 5 shots The first 2 went left last 3 went 10 ring. Not sure what was going on seems to be all good now. Didn't use the chrony. But very happy happy. Looking forward to more range time

100 gr A-max
Hornady brass
cci 450
8208 30.2
shoulder 1.210
coal 2.150
2.160 I'm touching lands

[Savage Shooter]

You only fired one 5 shot group - with a 2 inch spread? I am not sure I would declare "all good now" just yet. (Although if you were getting scattered 2"+ groups before, I could see the reason for being "happy happy".) What's your twist rate on your barrel? AA likes to go with faster twist rates as they shorten the barrel length, but if you have a 1:7.5 instead of 1: 8.75 twist, your barrel might be "on the edge" depending on your velocity with the 100 gr AMAX. The faster twist rate might like a slightly longer bullet. Have you fired more groups since putting it back together? Do you have different (i.e., better) results with factory 123 AMAXs?

[Blacklab]

Yes Savage Shooter I averaged 1.5-2.0 all day. Now it looks like I'm on the my way to sub moa finely. Barrel is a 18 inch 1/8.

Klem Not sure about normal lol but those are my numbers.

[LRRPF52]

Is it a lightweight barrel by any chance? I took 2 lightweight 18" Grendel's to the range last week, and the slightest errors in fundamentals will open the groups.

Firm rearward pressure and strict attention to fundamentals produced sub-MOA groups consistently. As soon as I relaxed the position a bit, ignored breathing, with inconsistent trigger break, and they would open up.

[Blacklab]

Thanks for the insight LRRP52. Yes it's a lite barrel.

[mseric]

2.16" touching lands...a fair bit shorter than the mag length, is this normal (never used the 100AMax)?

No, but it has happened.

http://www.65grendel.com/forum/showthread.php?224-6.5-Throating-Reamer

http://www.msrhunt.com/post/grendel-compound-throat-and-rounds-getting-stuck-6783926

[Klem]

No, but it has happened.

http://www.65grendel.com/forum/showthread.php?224-6.5-Throating-Reamer

http://www.msrhunt.com/post/grendel-...-stuck-6783926

That's a pity, for all the reasons in the links. Plus a shorter chamber is a loss of case capacity. Any load data from tables and the forum will need to be discounted by about 1/2 a grain of powder to be safe (ref: Quickload).

[rasp65]

With my AA barrel 100 A-Max OAL is 2.210"