Howa Mini Load Development Journal

[Paringa]

Started the process today. Virgin Norma brass so decided to form it all up doing some powder/chrony testing first.

100gr NBTs over ADI Benchmark 8208 (Australian Powder). CCI 215s.

Seated around 24thou off the lands just for powder/chrony testing.

I’ve gotta say, very very stable with this combination. ESs maxing out at 30fps but most in the low teens.

ADI published 29gr start and 30.8gr as max although this seemed too compressed in the Norma cases, so I settled with 30.6. I measured case head expansion at each fired 0.2 increment and it stayed a consistent 1.5thou from min to max charge. Re-primed max load and still firm press fit, so pressure seems very tolerable.

Very pleased to find a nice stable patch over 2800fps between 30.2 and 30.6 with ESs 15, 12 and 13, so will reload them in formed cases to shoot for groups. Will pick best group and then try to improve that with seating depth increments of 3thou in formed cases.

Will repeat this whole process with 123gr SSTs.

Stay tuned

[LRRPF52]

Nice. What barrel length do you have?

100gr NBT is the first 100gr bullet I experimented with after I did load development with 123gr Scenar about 12 years ago when I first got into Grendel.

I had some good combos with 8208XBR and 100gr from my first 16” AA barrel/bolt combo.

8208XBR is a great powder for the 100gr cup and core bullets in Grendel for case fill/velocity optimization.

[Paringa]

22” Sporter

[Paringa]

Round 2 of powder/chrony testing, this time with 123 SSTs

Virgin Norma brass

123gr SSTs over ADI Benchmark 8208 (Australian Powder). CCI 215s.

Seated around 24thou off the lands just for powder/chrony testing.

Again, very stable ESs, low of 11 and high of 23, although in this case the ES node was at the lower end of the charge strings, with velocity avg 2395.

ADI published 26.6gr start and 28.4gr as max, just starting to compress. Again, I measured case head expansion at each fired 0.2 increment and it stayed a consistent 1.5thou from min to max charge. Re-primed max load and still firm press fit, so pressure, again, seems very tolerable.

2 things stood out with the 123 SSTs over the 100gr NBTs. Speed and Recoil. Working within ADI limits, the 123s ran 300fps slower, topping out bang-on 2500fps compared to the 100gr NBTs 2825 (and where the NBT's ES node was at the top end of the charge string). Felt recoil was significantly greater, and although still a pussy cat, it's probably stepping past the realm of a kid-tolerant round and into a place that makes the round less unique for power vs recoil.

Interestingly energy comparison puts the 100gr NBT at 1772 ftlb and the 123gr SSTs at 1707 ftlb so I'll take the flatter shooting, lighter recoiling, harder hitting 100grainer any day.

All my brass is formed now, so I'll first shoot some groups using the 100gr NBTs with 30.2, 30.4 and 30.6gr.....pick the best one, and see if I can improve with seating increments of 3thou.

Stay tuned

[PaulieV]

Thanks for sharing mate, it's got me interested in the 100gr NBTs for sure. I'm using factory Hornady Black/American gunner at the moment and will have around 500 once fired brass soon. Already picked up the 123gr eld-m and a kg of 8208, so will add some 100gr NBTs in the mix too.

[Paringa]

Will be dropping back to lower velocity nodes as reshooting 30.2 and 30.4 with the 100gr NBTs today went over pressure.