300 Norma Improved 35 degree

[Ledd Slinger]

I tested Remington 9.5M in my first 300 NMI with the single shot Defiance and 30” Broughton 8 twist barrel. As far as accuracy, they shot good groups at 500 yards. Never did ladder test them tho because the 215M seemed to edge everything else out in that barrel. Haven’t tested 9.5M in my current NMI with the Proof barrel yet.

The only primers I will NOT waste time testing anymore is Winchester. I’ve never had WW primers shoot good in anything. Federal, CCI, and Rem primers are all good quality and all can give great accuracy.

 

[tom]

Round two for today. Will be shooting the same ladder/pressure test with a bushing change next. Switched to cci 250s and gave the barrel a scrub. 80 rounds down it at the start of this session.




Maybe this time she'll shred one! 245s v570 cci250, ff only brass. It's a bit windy, but should be good enough to get the data I'm after.

Tom

 

[Alex Wheeler]

Barrel dimensions

 

[Ledd Slinger]

Holy crap that’s fast! No flattened primers? What about case head measurements, any notable expansion on the top charge?

 

[Ledd Slinger]

Barrel dimensions

And maybe the fact that the barrel is a mile long. Lol.

How do you spec groove diameter on a button pull barrel? Not like cut rifling when less or more cuts can be made. Would need to make a new button and most manufacturers won’t do that for a one-off barrel. Then with manufacturing claimed tolerances of +/-.0002” on both cut and button pull barrels, I’m not sure how anything could end up that exact anyway. So do you just measure multiple barrels and select them to your liking? Similar to sorting bullets perhaps.

 

[Alex Wheeler]

It's not a button and I can order whatever i want. This ones unique.

 

[tom]

Almost crossed myself up in the wind, but here's how they printed. Will check these out when I get home, but I can not make out any pressure signs, the bolt lifted easier than when dry firing with everything shot to this point.

Tom

 

[Ledd Slinger]

It's not a button and I can order whatever i want. This ones unique.

Thought it was a Broughton?
Makes more sense being able to tweak if it’s a cut barrel

 

[Alex Wheeler]

Thought it was a Broughton?
Makes more sense being able to tweak if it’s a cut barrel

Not a broughton. But a button can be tweaked too

 

[Ledd Slinger]

Almost crossed myself up in the wind, but here's how they printed. Will check these out when I get home, but I can not make out any pressure signs, the bolt lifted easier than when dry firing with everything shot to this point. View attachment 1227093

Nice. Looks like the 245s have the same 3175-ish upper node spot that I found with the 220s

 

[Ledd Slinger]

Just went back and looked at the barrel brand in the thread. Don’t know why I thought it was a broughton. My mistake.

Another fast Brux. Very nice

 

[tom]

Just went back and looked at the barrel brand in the thread. Don’t know why I thought it was a broughton. My mistake.

Another fast Brux. Very nice

Brux Bullet Shredder. And despite the obvious brass being a tenth or so bigger each increment, nothing i can measure is scaring me. Now this was "ff only" brass, and I have one more set of that cycle to run some seating tests on. Then I'll decide on what to do with the ff + 1 cycle. Obviously back to powder work, but maybe with the 250 a tips. I'm not 100% sure though, depending on what groups look like playing with seating on these 245s. I am right on 100 rounds fired now, and it might creep up yet. Although the node (charge) is exactly where i would've predicted despite the speed up today. We also have to remember this brass won't settle in until a few firings. My past experiences with 338 lapua based cases also tells me this might well be capable of things on "FF ONLY" brass, that won't be able once settled in.

Tom

 

[taylorw]

Great test. I wouldnt give up on the 210 or 250, they may tune up with a powder tweak. If you plan to hunt cold weather I would be looking at the 250 and 215. Have not tried remington primers yet but plan to. Great input, thanks.

Ok. I think I’ll run the 250’s & 215M’s side by side at distance since this was a small sample. Probably stick with those 2 since I’ll more than likely only be using this rifle in cooler weather. I added the other 2 bcs I was just curious. Lol
I think I’ll try some different bushings once I get powder roughed in. I have a .336, & .334 bushing but may grab another one at .332 since I think GlennK had good luck with higher tension?

 

[taylorw]

I always found great accuracy with 215M. It’s the ladder testing where the 250 worked better for me. My groups with the 215M are actually smaller than groups with the 250. But the POI with the 250 is much more consistent with my rifle in a ladder test so that’s why I use them.

Appreciate the advice.. Where did you end up on bushing size?

 

[Alex Wheeler]

Yes but hes annealing. 336 has worked best for me without annealing.

 

[taylorw]

Yes but hes annealing. 336 has worked best for me without annealing.

Oh ok. Makes sense.. thanks

 

[Ledd Slinger]

Appreciate the advice.. Where did you end up on bushing size?

My chamber is a bit different with a .339” neck so my bushing size won’t apply to your rifle. I have to turn case necks.

However, I started with a .334” bushing, but ended up using more neck tension with a .332”. Most loads in the two rifles I’ve had seem to shoot better with a thou or two extra tension if that’s any help.

 

[tom]

When I run the same exact powder ladder with different bushings, ONE of the things I'm looking at is how wide does it kick sideways when I hit a node. Of course if you shoot them in big wind it's even more obvious which is less wind sensitive. But in good conditions I can still pick up on it. I've not seen much effect on the actual charge/velocity the node is, but have sometimes had a bushing widen that spot as well.

Editing to add this...When you can't get the width to go away, switch the dang powder! Lol

Tom

 

[Dm6]

With a no turn chamber for lapua brass what size range of neck bushings would one need to cover all the bases? Also is does anyone have data for the 230 atip since the Berger’s are hard to find?

 

[Alex Wheeler]

.336" is a good place to start. Thats about .002"neck tension. 230 Bergers are out there keep looking. They are worth it.