Replace factory S&B projectiles?

[biometrician]

I've got an AR10 in 6.5 creedmoor that shoots about 1-1.25moa with Hornady 140gr ELDM. I got several cases of S&B 140gr FMJ for ultra cheap from a buddy, and my rifle only shoots about 3moa with that ammo. However, when I shoot both factory loads over a chronograph the S&B has an SD of 6-8 and the Hornady an SD of 14-16. I know SD isn't everything, but it got me thinking.

So, my question is, why not just replace the projectile on the S&B with a better projectile?

What I'm thinking is pull the projectile with a cam lok puller and then seat an ELDM in place of the old bullet. I can see the difference in bearing surface between bullets leading to pressure issues. Also, might need to run cases through a neck die to get enough neck tension to work in a semi-auto.

Has anyone here given this a try?

 

[Mike Casselton]

It's called Mexican match.

I recommend pulling 5-10 and replacing the bullets to see how they shoot and to check basic pressure. If they are good, rock on.
I doubt you'll need to resize the necks. I've never had to.

 

[fdkay]

You may want to pick up a Lee factory crimp die and put a lite crimp on the new bullet.

 

[BuildingConceptsllc]

I've got an AR10 in 6.5 creedmoor that shoots about 1-1.25moa with Hornady 140gr ELDM. I got several cases of S&B 140gr FMJ for ultra cheap from a buddy, and my rifle only shoots about 3moa with that ammo. However, when I shoot both factory loads over a chronograph the S&B has an SD of 6-8 and the Hornady an SD of 14-16. I know SD isn't everything, but it got me thinking.

So, my question is, why not just replace the projectile on the S&B with a better projectile?

What I'm thinking is pull the projectile with a cam lok puller and then seat an ELDM in place of the old bullet. I can see the difference in bearing surface between bullets leading to pressure issues. Also, might need to run cases through a neck die to get enough neck tension to work in a semi-auto.

Has anyone here given this a try?

How many rounds did that SD hold for with the SB ammo?

 

[biometrician]

How many rounds did that SD hold for with the SB ammo?

I've shot 2x 20rd strings and a 10rd string. It's quite remarkable.

 

[BuildingConceptsllc]

I've shot 2x 20rd strings and a 10rd string. It's quite remarkable.

Wow! That is incredibly good. Yeah it may be worth Mexican match of you can pull em without damage and test a few first.

 

[stello1001]

I wanna say that I've shot S&B grendel ammo that actually jams into my rifling and shoots poorly accuracy wise. It also shoots with pressure and I get stiff bolt lift but boy the SD & ES numbers are good for being factory ammo.
I say go for it