Consistency Matters

[rodell]

I've been working up a load for my Blaser 30-06 barrel and Nosler products.

In this picture, the top row is 180 Accubonds and the bottom row is 150 Partitions. No sight adjustments were made, a minimum of two minutes between shots, minimal wind at the time of the shot and a distance of 100 yards. No scope adjustments were made. Each type was shot round-robin.

The AccuBond was .080" from the lands and the Partition .025" from the lands. Powder is the new Enduron IMR 4451 (approximately equivalent to H4350). The orange dots are 1.5",

I had both new Lapua cases that had been sized, and, once fired Lapua that had been sized. Both sized in the same die, using the same lube and press.

A "0" indicates a new case, and a "C" indicates the load was crimped with a Lee Factory Crimp die.

If nothing else, this test shows the importance of consistency when doing load development! Even small changes mean a lot.

(There is no third shot on the 150 line and the "0" column. The round failed to ignite - the primer failed. First one I've ever had. It burned, but very little and not enough to ignite the powder.) Too bad, I might have had a 150 PT load that had the same POI as a 180 load! I'll shoot it again when I have time.

 

[DrMike]

Well, at a minimum, you have a great load in the 180 grain with a case that has been fired once. Crimping doesn't appear to make a great difference. Hard to make a statement concerning the 150 grain Partition. It is possible that seating the bullet closer to the lands with the 150 will tighten the accuracy..

 

[Polaris]

The left/right shift is interesting. Likely causes if no wind: parallax, cheek weld, tension/pressure changes on barrel channel.

The Blaser is a switch barrel yes? Not very familiar with this type of rifle, may lend additional variables inherent to the design.

I would shoot a 5 round group with each without any extra time between shots before tweaking them too much. See if you still get the left/right shift with a steady string of fire.

 

[rodell]

It is clear to me the once fired cases are more consistent. In the absence of any once fired, I should crimp. That didn't hold true for the 150's though.

This barrel is the sporter weight, so I always allow the two minutes to cool. It never gets too hot to touch, at least at our usual ambient of 60 degrees or so.

 

[ElmerThud]

Yes consistency definitely matters. Fired cases are without doubt always better than new - IF -
They are carefully prepared for reloading with accuracy.

Personally, I now never neck size.
I decap separately from F/L resizing with a universal decap die.
Always full length resize to fired headspace dimension. (With the decap rod backed off and correctly centralised in the die)
Every third firing anneal the brass.
Care with bullet seating and finally always crimping using a Lee FCD.. in my view, gives better neck tension consistency...I always see lower ES and consistent MV with crimped rounds.

Works for me...

 

[Wyo7200]

Neck tension has a significant influence on the burn rate in QL. I can see a good 30+ fps swing between using a mandrel and the ball expander on the rcbs dies. I haven't found the ratio yet as I do not measure the tension, but I'd say its .001-.002 difference in tension. Tried this on 22-250, 6.5 creed, .260 rem, .308, and 25-06, powders R17, H4350, R25, and varget with similar results.

Cool test

 

[sask boy]

Thank you for the post as again I learned something new :wink:!!!

Blessings,
Dan

 

[DON]

This thread is very interesting to me. I have found with my 300 RUM I get better results with 1x fired casings verses new brass, even though I full length re-size. trim etc and deburr the primer pockets and trim to length as needed for both. The outcome is always the same.

Don