30BR - High node or low node

[Gollum]

Doing some load testing with the 30BR. Using BIB 118 10 ogive bullets,Tungsten coated), over H4198 and Fed 205 primers.

Loaded up 5 rounds each 32.4, 32.8, 33.2,33.6,34.0,34.2,34.4,34.6,and 34.8 gr. Loaded 100 rounds total, 50 0.030" off the lands, 50 0.015" into the lands.

Shot everything @ 200 yards, pretty calm conditions, but a wisp of a breeze occasionally. The 0.015" jambed bullets shot all over the place, I was getting pretty disgusted at that point. The I shot the 0.030" off batch- -wow, what a difference. This is how they should shoot! a lot of cutting the same hole stuff, with a few fliers.,I ain't the best shot, lots of learning to do)

I did find 2 loads that were outstanding, compared to the rest: 32.8gr, and 34.4gr. I'm assuming these are the "high" and "low" nodes. The loads on either side of both of these were acceptable, these loads were noticeably better. Notice that there is a .4 grain step around the 32.8, but only a .2 gr difference around the 34.4 load.

My question for discussion - should I load for the high node, or the low node?

What band do you usually find more forgiving in different temperature conditions?

Is there any other variable I should try? Deeper? Closer? When you're 0.030" off, how far do you need to change it to be significant?


Strange thing on the jambed loads vs the 0.030" off loads. The recoil from the jambed loads was "sharper". don't know how to describe it, but the gun seemed to come back into my shoulder faster. I don't have a chrono, so I have no idea of velocity.

 

[AlNyhus]

Gollum:

Approach #1: Here's what I would do: using a bushing that's .004 under what a loaded round measures,ie: .328 use a .324 bushing) and the 34.4 weight, start at .030 jam and shoot 3 shot groups @ 100 yds. changing the seating depth .005 at a time.

Once you identify some good groups, go back out to 200 and fire 5 shot groups of those. Then, when you find a good shooting 20oyd. load, load 25 rounds and shoot 5 groups to verify.

Approach #2: Use the same method as above, but at the lower charge weight that gave the best accuracy. After identifying the best 'jam', go up in powder charge until they start hammering into a hole...that should be in the 34.0-34.8 range. It will be compressed, but that's fine. Most 30BR shooters I shoot with use loads in the 34.0 range but your gun will tell you what it likes. No problems shooting the 34.0 in the heat,90 degrees+) with my gun..but they can vary depending on throat angle, freebore, barrel internal dimensions, number of lands, etc, etc.

Editted to add Approach #2.

Good shootin'! Let us know what you find, okay? -Al

 

[Aussie_bob]

I don`t have the long experience of Al on this but i have just been through this exercise and now have my 30BR shooting very well over many ranges 32.8grs is where i ended up but .2 either side doesn't seem to make a lot of difference but try to load all the same i was jamming .020 but had some one give me a nudge and mention push back so loaded and chambered quite a few loads and found that it was consistently pushing back so that i was only .015 into the lands so i adjusted my seater and that's where i load i have .002 neck tension and can unload a round without having to worry about pulling the projectile.
It is now shooting low .2xx at 100 down into the .1xxs and low .2xxs at 200 shot 2 inch groups at 400yards and one at 1.25inches it is getting better the more i learn about it now i will weigh each load as i have been throwing with a Harrell and there can be a .2 grain discrepancy either way.
I mainly shoot Varmint for score but intend to take on the PPC crowd latter in the year if i can keep my groups consistently low i can do it as i will be using heavier projectiles so should buck any wind better. What i should mention my rifle was chambered for this particular projectile so i do not have to seat long to be into the lands and the powder comes to the bottom of the projectile i don't believe i could fit 34grains with out compressing fairly well.

 

[TDuley]

I shoot my 30BR, right at jam. With vv130 at 33.0 Gr's. It just don't seem to me that the hot loads shoot any better,but I have not shot that munch. And I like the cci primers, that's just me, I guess. AL shot your postal?????