New to Handloading…need a second opinion

[cbn]

I have a friend who is an experienced handloader, retired local swat sniper, load up some 6mm arc for my bolt gun.

We are using once fired Hornady brass (not annealed), CCI 450, Hornady 105 gr Match and Leverevolution. Loaded to factory length using Wilson full length sizing die.

The attached 10 round group is 29.2 grain charge weight. Hole 9 & 10 the bolt was heavier than normal when opening and closing. 6 & 7 I’m confident were my fault. If I remove these four shots it’s about a 1/3 moa group. At the start of the session I shoot 1/2” groups with Hornady Black 105 so I’m confident in my fundamentals, ability to call the shot and gear.

Below are the velocities. ES 68 and SD 16. Both are obviously too high.

2900
2909
2861
2889
2881
2887
2881
2881
2929 (heavy bolt)
2908 (heavy bolt)

Is the heavy bolt due to improperly sized brass?

For my purposes a group 1/2” or less is fine.

Any recommendations on how to move forward?

Friend wants to try 29.0 and 29.4.

 

[Kadams1563]

What speed does the Hornady black run? Your speeds seem fast to me but admitted I haven’t messed with the 6 Arc yet.

 

[cbn]

The lots have been about 2820, 2850 and current lot is 2910.

Very similar to 6br.

 

[cbn]

One item I should mention is that I’m using the 6 arc MDT metal mags. 10 rounds of factory ammo fits; however, I’m only able to fit 8 rounds of the handloads.

 

[Kadams1563]

Boot heavy on closing would indicate the cases need to be bumped back or sized down some more.

Do you have a comparator set to measure your shoulder bump?

On thing you could do is disassemble your bolt, resize your brass, then close the bolt on the brass to see if it falls with no resistance.

If you have any resistance at all they are not bumped back far enough.

 

[Mike Casselton]

The velocity you're getting seems quite high.
I shoot mostly 6-BR and if I tried to run 2900+ fps, I'd have hard bolt lift too.

I'd recommend you targeting 2800-2825 fps and enjoy longer brass life and zero extraction issues

 

[cbn]

@enginerd

 

[spamassassin]

Was some of the brass fired in another rifle at any point in its life?

 

[cbn]

No.

 

[spamassassin]

No.

Well, that shoots down one idea. I'd had a problem very like this with hard bolt lift on some rounds after someone who shall go unnamed used my ammo in his gun. I never got those cases to work again without a hard bolt open/close. I'll show myself out.

 

[cbn]

Well, that shoots down one idea. I'd had a problem very like this with hard bolt lift on some rounds after someone who shall go unnamed used my ammo in his gun. I never got those cases to work again without a hard bolt open/close. I'll show myself out.

I appreciate the thought though!

 

[cbn]

The velocity you're getting seems quite high.
I shoot mostly 6-BR and if I tried to run 2900+ fps, I'd have hard bolt lift too.

I'd recommend you targeting 2800-2825 fps and enjoy longer brass life and zero extraction issues

Thank you. Will look at this further.

 

[cbn]

Boot heavy on closing would indicate the cases need to be bumped back or sized down some more.

Do you have a comparator set to measure your shoulder bump?

On thing you could do is disassemble your bolt, resize your brass, then close the bolt on the brass to see if it falls with no resistance.

If you have any resistance at all they are not bumped back far enough.

I think this is the problem. Ordering the comparator now.

 

[cbn]

I think this is the problem. Ordering the comparator now.

Thank you guys!