XBR 8208 range results for 100 and 120 gr NBT

[PA_Allen]

I finally was able to pick up a pound of XBR 8208 to try. I only had time to try a few loads with the 100 gr and 120 Nosler Ballistic Tip Bullets.

All of the loads were fired through my 20" Lothar Walther Barrel with the CSS chamber.

Chronograph screens 12 ft. from muzzle, all velocities reported from chrono. (not corrected to muzzle velocity)

All loads used new Lapua Brass and Rem 7.5 primers. The velocities listed are average of 5 shots.


120 gr. Nosler Ballistic TipXBR 8208100 gr. Nosler Ballistic TipXBR 8208TOO HOT! approx 2900 fps!

My targets were set at 200 yards. All loads grouped well (around MOA) considering the switching winds that were present today.

With the 120 gr NBT, the 28 gr load looks like a winner, and the 30.5 gr load looks nice for the 100 gr NBT.

I would NOT recommend the 31 gr load with the 100 NBT. The velocity jump was highly nonlinear compared to the 30.0 and 30.5 gr load. I only fired 3 of the 31 gr load, and I am disassembling the rest.

I hope to test 8202 with the 100 gr TTSX soon. If my tests continue to be positive with this powder, I may start using this for all my 100 though 123 gr loads to simplify things.

Best,
PA

[gophernuts]

What is the max load for XBR 8208?

[mseric]

What is the max load for XBR 8208?

http://data.hodgdon.com/cartridge_load.asp

[mlmiller1]

interesting that Hodgdon doesn't show a LVREvolution load for the grendel.

[steel89]

120 gr. Nosler Ballistic Tip – Overall Cartridge length = 2.225”

XBR 8208
28.0 gr – 2513 fps, SD 13.6, ES. 33.2
28.5 gr – 2546 fps, SD 12.8, ES 34.1

PA_Allen,
My NBT/8208 range stats are very close to yours and I was getting sub-MOA @100yds. I really like the combo and plan on using that as my go-to whitetail round this season. What were your groups like at 200yds?

[PA_Allen]

steel89,
Here is a group at 200 yds using the 120 NBT and 28 gr of XBR 8208

[/IMG]

and here is one at 200 yds with the 100 NBT and 30.5 gr of XBR 8208



In general my groups were nice vertically, but had some horizontal spread from the switching winds (and my poor bag technique!).

Sounds like you have a good whitetail load. Let us know how it works out for you.

Best,
PA

[LRRPF52]

XBR 8208
30.0 gr – 2760 fps, SD 12.2, ES. 30.6
30.5 gr – 2785 fps, SD 9.2, ES 20.4
31.0 gr – TOO HOT! approx 2900 fps!

When getting past 29.5gr with the Grendel, I prefer to add charge weight in my load development in no more than .3gr increments, and usually .2gr so I can creep up on that non-linear pressure curve that others have commented on and experienced. I would not advise .5gr increases as you start to approach max loads.

Did you see any pressure signs on the brass? Cratering, excessive ejector extrusion, pierced primers, significant case length increase?

Excellent post, by the way. Your velocities and experience seem to be right with mine and all the published data on 120gr bullets and appropriate powders.

[PA_Allen]

When getting past 29.5gr with the Grendel, I prefer to add charge weight in my load development in no more than .3gr increments, and usually .2gr so I can creep up on that non-linear pressure curve that others have commented on and experienced. I would not advise .5gr increases as you start to approach max loads.

Did you see any pressure signs on the brass? Cratering, excessive ejector extrusion, pierced primers, significant case length increase?

LRRPF52,
Thanks for the comments and questions. Your advice to proceed in .2 gr increments towards the max. loads is very sound. Like so many of us, my range time was limited so I proceeded in .5 gr increments to "bracket" a good working zone for future loads. There was no significant pressure signs on the brass with the 100 gr NBT and 31.0 gr of 8208....that is the sobering part. Without the chronograph telling me I was in trouble, I never would have known anything was amiss. I am a firm believer that velocity is the best sign of pressure for the average handloader without proper lab equipment. If I am getting significantly more velocity out of a bullet weight/powder burning rate combo than the pressure testing labs have reported as safe, it tells me that I likely am over pressure. The nonlinear nature of the velocity increase with powder charge increase was also a flashing warning sign.

I am getting such good performance out of these loads that there is no need to push things to the edge. I look forward to testing this powder some more in the Grendel and in the .223 for high power XTC in the future.

Best,
PA

[LRRPF52]

Sometimes Chrony brand chronos, or others in that price range will register crazy velocities as an error with the chronograph, but if you had several in the 2900 fps range, then you're probably in insane pressure territory. I'd be interested to see what a model would indicate the chamber pressure was. You definitely do not have a lot of play to work with in the Grendel when it comes to loads using these long projectiles with significant bearing surface, and limited powder capacity. The case is extremely efficient in getting decent velocities for the size that it is. It kinda reminds me of .30 TC and how it gets higher velocities than .308 and .30-06', even though it has less case volume than both of them. Once we hit powder capacity though, things get unpredictable, which I will be more than happy to stay away from, even if I stay in the 2500's for velocity with 120's, and low 2700's with 100gr. When you start compressing loads in these cartridges, you're introducing different burn characteristics for the given powder, and that may be one major contributor to the non-linear spikes. I'm no engineer, so who knows...

[Bill Alexander]

Mv is not that important, what counts for hunting is impact velocity. I will always trade accuracy and sectional energy for velocity in a hunting load.

[StoneTower]

Mv is not that important, what counts for hunting is impact velocity. I will always trade accuracy and sectional energy for velocity in a hunting load.

So if in the case of PA_Allen's hunting loads:

120 gr Nosler Ballistic tip with **gr of TAC or RL15 - 13 deer 2417 FPS

100 gr Barnes TTSX with ** gr H335 - 1 pronghorn, 4 deer, and 1 coyote 2765 FPS

Where is the trade off between sectional energy and velocity? For my hog hunt down South I chose the 100 TTSX because I was required to use a lead free bullet. When I hunt where I live up North I can use lead bullets as I have a choice.

With the Barnes bullets one has to make sure that you have a impact velocity that will properly open the bullet. I like the fact that the Barnes TTSX did not leave any bullet fragments in the meat.

[sneaky one]

That's exactly why I use the GMX's in a lighter wt. , to up the speed to ensure great expansion. I am going to switch to xbr 8208 to get max. performance from these units, they open up perfectly, at 2700-2800. Yet another 100fps. ensures that I can add 100y. if needed , say to a max of 350-400y. Very accurate bullet also. I plan on contacting Bill A., and Hornady in the near future about possibly making an improved version of this lightened gmx- Grendel specific. If they would try some of my samples,- ( I'm 95% of the way to perfection on these- almost done- probably in a few weeks) - I think this is a winner for the Grendel guys, as these bullets hit like a Mack truck . The Accubonds in 115 grn. lost 30 grn. of wt. in my h2o tests last month, the GMX lost 1 grn.= the tip , awesome performance! If there is no interest, I'll be starting up a small scale bullet company next yr. BTW, I worked on the 100 Barnes unit last yr., yet lost interest for 2 reasons.- copper only, is not as clean as gilding metal. - the Freedom group bought Barnes. Phew !