Nosler 125gr partitions and 8208

[Splatt]

Shot my chrono some years ago, and haven't replaced it.
What should I expect for velocity from 28.0 grains of 8208, out of an 18" barrel.
6,000 feet elevation if that matters too much to some.
I'm thinking @2450 or so.

Thanks all.

[A5BLASTER]

2350 to 2400

[Splatt]

Ok. Still puts me to between 3 and 400 yards to shoot a deer, based on 1800 fps.

[TropicalVibe]

My 18 inch Grendel AR barrel will consistently move an 123g AMAX at 2450 over 28g of 2808. I have no expierance with the 125g Partitions in the Grendel. I hope this helps in some way!

Cheers,
TV

[Splatt]

Make that 425 yards but just over 34 inches of drop with a 200 yard sight in.

[CJW]

Thanks guys,

Keep the info coming in.

[1Shot]

My 18" Oden Works barrel gets average 2500 fps with 120 Speer Gold Dot with 28 grs IMR 8208 so my guess with the 125 Partition would be 2400 fps or a little above. I hope you can find expectable accuracy with the Partition. In my experience in different calibers is they will either shoot great or not at all.


Also keep in mind that the down to 1800 fps for expansion means ANY EXPANSION. Most bullets going this slow will only just barely widen the nose a little. The Nosler long range Accubond 129 gr on the other hand will expand pretty good at 1800 fps because they are designed to expand some down to 1300 fps. They also have a much better ballistic coefficient and cost about the same or just a little less IF YOU CAN FIND SOME. Good luck.

[LRRPF52]

You should expect excessive pressure unless you have a long throated chamber, as that load is 1-1.5gr higher than max.

The 125gr Nosler Partition really should be treated carefully, more inline with load data for 129gr and 130gr cup and core bullets due to its resistance to being forced into the bore. As most are probably familiar already, the Partition is literally a wall that separates the frontal and base lead cores of the bullet in order to deal with excessive impact speed at closer ranges that were being generated more and more as centerfire hunting rifles in the US latched onto the velocity-chasing trend in the early-mid 1900s. In order to deal with the fragmentation effects of closer range shots, Nosler developed the Partition so that hopefully the base core at least would be retained so that the hunter could still get significant penetration on those closer shots when the front came apart.

Because of that center wall, you now have a cross section in the middle of the bullet that is basically like a solid in that location, so when the projectile is forced into the bore, instead of the copper cup being able to compress around and inward on the soft-as-soap lead core, it has to compress on a solid little wall of copper as well.

This is why you want to treat it like a 129/130gr cup/core bullet and not a 120-123gr.

I'm referencing Volume II of the 6.5 Grendel Handbooks, as well as Nosler's own load data for this bullet/powder combo.

You'll find it on page 90 of Volume 2 with 27.5gr of 8208XBR as max with 2.250" COL and a Rem 7 1/2 SRP, and Nosler's data maxed at 27.0gr using Nosler brass, Re, 7 1/2 SRP, and 2.240" COL.

28.5gr of 8208XBR is pushing it well past any published load for the 125gr Partition.

I hope this helps.

Here's a pic from a forum member whose wife shot a bull elk with a 6.5 Grendel/125gr Partition from a 20" AR15:

[Splatt]

Just 28.0 grains....
Primers are fine, just resized, cleaned, and reprmed those test fired rounds.
Primers still tight going in.
With a 5 shot group like this at 100, I'm not changing anything.

[Splatt]

1shot,
There's a box of 100 lr 129gr Accubonds at my local sportsmans.

[LRRPF52]

With that load, I just ran it through a Grendel internal ballistics computer using reference loads with specific charge weights and speeds.

One says you're somewhere around 2523fps. I used Grendel Handbooks for this reference with a 20" barrel pushing 2526fps with 27.5gr max load, which seems on the fast end of what we'd expect.

The other says 2389fps. I used the Nosler 27.0gr max load from a 24" barrel for this one, plugged in 18" with a 28.0gr load.

What does your brass look like?

[Splatt]

Just fine. No shiny spots, and primers are very firm going in.
I've reloaded since the early 80's.
This isn't new to me.
Not that you think I don't know what I'm doing.
I'm also using federal small rifle primers.
Here's what I have left to load out of 100.
Oh, and yes these are my test batch casings from this 28.0 grain loading.

[LRRPF52]

Those are processed, re-sized, and re-primed.

I was thinking what fired brass looks like, not that brass and primers are a reliable indicator of pressure, but if we see cratering, flattening, and significant ejector channel extrusion, then we don't ignore those symptoms.

Even when you really push 6.5 Grendel, I haven't had any loose pockets with Hornady brass.

With Federal and the LRP PPU brass, I have seen loose pockets from normal loads in ARs.

In contrast, take the Federal brass and push it in a bolt gun, and primer pockets have been tight for me.

All I am saying is that based on the available published data we have from multiple sources, 28.0gr is .5gr-to-1.0gr higher than published loads, and that powder is a known pressure spiker with normal (non-partitioned) cup and core 123gr bullets in the 27.8-28.5gr region.

Using a 125gr Partition is now pushing that safety margin down below any of those charge weights. I don't think you're in extremely dangerous territory, but definitely looking to shear a lug, especially if you're running a Mid-Length Gas System.

You'd be fine in a bolt gun. What barrel make, gas port diameter, and gas system length do you have?

[Splatt]

I already processed the brass, yeah, primers were modestly flat, so that tells me I'm hot.
PSA, 18" stainless, with rifle length tube, non adjustable, steel GB. Dont know port size.
I am using a GB logo bolt.
I am very sure, I wont be using these a hot summer day, by what your showing me.

[Splatt]

As a side note, since I'm new to this cartridge, and powder, if you think its unsafe, I can always pull em, and reload lower.