Flatline Precision 300 NMI’s

[Wedgy]

If you want to save the peterson I would turn the thick necks down to match the thinner ones... or just stick to the Lapua.

 

[Huntnful]

If you want to save the peterson I would turn the thick necks down to match the thinner ones... or just stick to the Lapua.

Yeah that'd be the only way. I'm not set on the Peterson. I'd prefer not to turn necks, so I'll just shoot it as foulers and load the Lapua for hunting. I'm going to switch everything over to Lapua for all cartridges anyways honestly. It's just the best.

I mean they both shoot great. Lapua is just more consistent and more predictable on target

 

[Mike D Texas]

Yes! It does a great job!

The issue is with the thickness of the necks not being consistent, so they're not getting consistently sized down on the initial FL sizing. So after spring back, they just aren't that consistent. I had to load 85 rounds to get 51 rounds that felt like they seated "decently consistent". With lapua you cannot tell from one round to next. They all slide in with equal pressure.

How are you gauging this? Strictly by feel? And on what press?

 

[Huntnful]

How are you gauging this? Strictly by feel? And on what press?

It's a single stage MEC. Yeah by feel. I can feel the mandrel go harder into some necks and lighter into others. And the bullets end up seating the same way.

 

[6.5x300 WBY]

IMPORTANT NOTE.

I noticed I was getting really inconsistent mandrel pressure while expanding, and seating pressure while seating in the Peterson brass. The neck wall thicknesses must be fairly inconsistent. I switched to Lapua brass and seating is SUPER consistent, which in turn made my groups smaller and more consistent. I shot that .33 five shot group at 455 yards with the Lapua. So today I needed to shoot the rest of the Lapua so I could have enough consistent pieces to prep for season. So I actually wanted to retest the 208's.

I loaded 13 rounds with 88.5gr. H1000 and 208's seated about .020 off. They had a velocity average of 3110fps and maybe an ES of 25.

The far left shot is the first shot after switching from Retumbo (another test) to H1000. And then the following 12 shots of 208 ELDM's shot a 3/4 MOA group at 100 yards.

View attachment 485155

I think I'm still going to stick with the 225's at 2950fps because they still shooter slightly better and slightly tighter ES. But I think any of my previous weird group/accuracy issues is probably attributed to the Peterson brass more than anything else.

I didn't look into it but does Alpha brass make 300 norma? It's my top brass I look for in any serious rifles for me. Lapua is my backup if I can't find Alpha. The consistency is stupid and Alpha packages their brass correctly compared to Lapua which I can't stand bulk packaging.

 

[Huntnful]

I didn't look into it but does Alpha brass make 300 norma? It's my top brass I look for in any serious rifles for me. Lapua is my backup if I can't find Alpha. The consistency is stupid and Alpha packages their brass correctly compared to Lapua which I can't stand bulk packaging.

Lapua JUST started individual packaging! And the brass is beautiful now. I hated their bulk packaging also! Brass would look like crap and 1/2 would have dented necks.

Their latest batch of 300 Norma brass

 

[Wedgy]

It's a single stage MEC. Yeah by feel. I can feel the mandrel go harder into some necks and lighter into others. And the bullets end up seating the same way.

You should add one of these to your kit.

ball micrometer | Brownells

Brownells is your source for ball micrometer at Brownells parts and accessories. Shop our vast selection and save!

www.brownells.com

Regardless of thickness and annealing some just seat harder or softer than the rest. I cull them for fouling but yes, getting top notch brass should reduce the number of bad cases.

 

[Huntnful]

You should add one of these to your kit.

ball micrometer | Brownells

Brownells is your source for ball micrometer at Brownells parts and accessories. Shop our vast selection and save!

www.brownells.com

Regardless of thickness and annealing some just seat harder or softer than the rest. I cull them for fouling but yes, getting top notch brass should reduce the number of bad cases.

Oh I totally agree. It's just much more apparent and a much broader spectrum of pressure differences with the Peterson.

 

[6.5x300 WBY]

Lapua JUST started individual packaging! And the brass is beautiful now. I hated their bulk packaging also! Brass would look like crap and 1/2 would have dented necks.

Their latest batch of 300 Norma brass
View attachment 485312

That's great to hear . My last batch of LAPUA was bulk 06. Didn't make me happy but now individually packed is awesome To hear. That's my 2 favorite brass.
1. ALPHA
2. LAPUA. If I can't get Alpha

 

[Mike D Texas]

It's a single stage MEC. Yeah by feel. I can feel the mandrel go harder into some necks and lighter into others. And the bullets end up seating the same way.

I used to think I was pretty good with feel until I bought an arbor press with a force pack.

 

[Huntnful]

I used to think I was pretty good with feel until I bought an arbor press with a force pack.

That will be a future purchase I'm sure haha. Because I believe consistent neck tension is far more important than the amount of neck tension in general

 

[Huntnful]

100 yard 5 shot zero check and a quick 3 shot group at 603 yards after the barrel cooled down. This is with my freshly loaded batch of 50 in the Lapua brass. I'll leave the bore dirty for longer range cold bore testing again now.

 

[Mark37082]

I believe it is time to start a new build. It's going to be tough to improve this one.

 

[Barehandlineman11]

For guys wanting to know annealing seating pressures. I did 6 over annealed 12 under and 20 at what amp annealer says to use. Same batch huntnful is running and also norma improved.