Benchmark or 8208xbr or maybe even something else

[GjGary]

8208xbr and AR Comp....jury still out on Tac still in testing phase.

X2 tac did well in my 18" BA with the 107smk but more work to do

[Popeye212]

X2 tac did well in my 18" BA with the 107smk but more work to do

Thanks for that info I am about try some of the 107's. I'll stuff a few with TAC.

[Jeepster18_88]

Thanks all! I saw it online but I refuse to pay hazmat unless I'm ordering large amounts. I'm not sure if Cabela's charges hazmat? I really don't want to order 8lbs out of the gate. I ordered a couple of boxes of 123gr SST and Eldm as well as a case of wolf just because a gun without ammo makes a crappy paddle. I couldn't shoot it today because someone has stolen every package shipped by the USPS since I've moved here. I don't plan on buying new manuals because I have them back home. I appreciate all the help. BTW, my Grendel Reloading manuals shipped USPS so I've got my fingers crossed.

[CaptnC]

Jeepster,
Take a look H335...if your reloading 7.62X39 you might have it already.

In my limited experience loading for a gaser, I've found 8208 a bit picky. When you finally find the sweet spot your good to go. But when your not in the node it shoots pretty loose. I burned a pound in two AR Grendel's trying to find an accurate load.

The H335 was easy...I could have nearly stopped at about any powder charge and had very acceptable accuracy. It didn't take near the powder to findicate a good node.

I'm also gather brass to start reloading for a couple 7.62X39 AR's and see H335 supplies the fastest velocities o I'm hoping it behaves the same way.

I'm also favoring 123 SST for both. And I also have the same concerns about getting ammo swapped...but they are too good of a bullet to not use them.

[Jeepster18_88]

CaptnC, glad to see someone from close to home. Thanks for the advice and I'll keep that as an option. I don't currently use H335 but I know it has a big fan base. My 7.62x39s are Radical Firearms and with factory ammo, they shot well enough to not give away, but barely. I wasn't looking for tack driving accuracy. I tried almost every 308-311 bullet that I could find and tried several different powders (I don't have my Log books with me). Accuracy was better, but not by much. Someone recommended 2 powders, I am trying to remember the other but the only one I found locally was Reloder 7, which many manuals have data for. Every group I've fired has been MOA or less with each of the bullets. Some have feeding issues such as the 130 SPFN Speer, but that's only with a full magazine. I would definitely recommend that powder as an option in the x39. Velocity has been better than factory ammo also at .5 great below max listed charge out of the 16" barrels. With the SST, it seems to be much more powerful than numbers on paper suggest!

[MarkS]

I've had extremely good luck with Benchmark shooting 123 SST's in my 12" PSA upper. Velocities max out just below 2300 fps, but that's not bad for a short barrel.
Unfortunately I don't have my data handy right now, but the SD and ES were both single or near single digits with my preferred load.

** Edit **
It looks like I misremembered my data. The very low SD/ES were for the 95gr VMax. Also, the 123gr ELD-M is retail Hornady Black ammo.

** Disclaimer: These are my loads for my specific rifle and may not be safe in any other setup. The use of CCI400 primers is highly discouraged in free-floating firing pin designs and some members of this forum have first-hand knowledge of slam-fires with primers that are not specifically designed for use in AR style firearms. **

6.5G_Data.png

[Jeepster18_88]

Thanks, feel free to share it when you get a chance if you don't mind. I'm open to all suggestions.

[LRRPF52]

8208 XBR is very temp stable and is common for .223 Rem as well.

Just follow good procedure, and don't exceed book max values.

We were shooting Friday and my buddy tried his 28.5gr XBR load under 123gr SMK in his 12" Grendel, and it had noticeable ejector shadows, but didn't look like significant extrusion from a hot load.

Hodgdon's published max load with that combo is 28.5C (compressed), but I would approach it carefully. Speed will be consistent across a wide temperature range.

8208 XBR does very well with 100gr class bullets like the 100gr NBT and 107gr SMK.

What's your barrel length and gas system length?

[Jeepster18_88]

24" RLGS now, but I'm already planning a 20" build soon

[roor]

To all the 8208 xbr with velocity data, how is your SD? The one time I ran it is was getting some kinda big numbers. Which showed in stringing. I switched over to n135 and got less stringing but don't have a chrono to get real info.

Anyone wanna donate a magnetospeed or lab radar?

[Jeepster18_88]

I just picked up some XBR but it'll be a little while before I can start reloading for the Grendel. I should be heading back to Texas next week so I will be getting everything together for testing before I come back to WV this time. I just got my scope mounted despite the mounts not fitting and I'm really happy with how it looks and feels. Hopefully it shoots as good. Thanks for all the help everyone!

[Mad Charlie]

What did you have to do to your scope mounts?

[Jeepster18_88]

I ended up filing the bottom because it wouldn't begin to fit the rail. It's been an issue apparently with the Nikon P-SERIES mounts as many reviews online have stated that they are undersized. By slowly filing it out, it allows an exact fit so I'm not really disappointed. My first reaction was disappointed, but I'm really happy with the results. It's snug enough that even if the bolt loosened on a hunting trip, it should still be accurate enough to get the job done at my hunting distances (it's happened before when an old bolt finally gave out at the valley of the thread). The only downside is that it scuffed the edges of the rail but I've already been considering duracoating the rifle if it I can get decent accuracy out of it.

[Popeye212]

To all the 8208 xbr with velocity data, how is your SD? The one time I ran it is was getting some kinda big numbers. Which showed in stringing. I switched over to n135 and got less stringing but don't have a chrono to get real info.

Anyone wanna donate a magnetospeed or lab radar?

Ballisitic Advantage 20" Sierra 120 Pro Hunter seating depths 2.55.2.50.2.45. 2.40 Corrected....Thanks Nuggin..get into to big a hurry sometimes.

Synced on: 2019-02-25 10:28:40
Series 2019-02-25_10_28_40 Shots: 5
Notes 28.0 8208xbr
Min 2473 Max 2503
Avg 2489 S-D 14.4
ES 30

Shot Speed
1 2473 ft/s
2 2503 ft/s
3 2503 ft/s
4 2493 ft/s
5 2476 ft/s
---- ---- ---- ----

Synced on: 2019-02-25 10:33:28
Series 2019-02-25_10_33_28 Shots: 5
Notes 28.0gr 8208xbr
Min 2482 Max 2505
Avg 2490 S-D 9.5
ES 23

Shot Speed
1 2485 ft/s
2 2495 ft/s
3 2485 ft/s
4 2482 ft/s
5 2505 ft/s
---- ---- ---- ----

Synced on: 2019-02-25 10:40:20
Series 2019-02-25_10_40_20 Shots: 5
Notes 28.0 gr.8208xbr
Min 2470 Max 2486
Avg 2475 S-D 6.4
ES 16

Shot Speed
1 2474 ft/s
2 2486 ft/s
3 2474 ft/s
4 2471 ft/s
5 2470 ft/s
---- ---- ---- ----

Synced on: 2019-02-25 10:45:39
Series 2019-02-25_10_45_39 Shots: 5
Notes 28.0 8208xbr
Min 2469 Max 2483
Avg 2478 S-D 5.4
ES 14

Shot Speed
1 2469 ft/s
2 2483 ft/s
3 2477 ft/s
4 2480 ft/s
5 2481 ft/s

I was testing different seating depths this session
Taken with Magnetospeed Sporter

[NugginFutz]

Synced on: 2019-02-25 10:28:40
Series 2019-02-25_10_28_40 Shots: 5
Notes 28.0 8208xbr
Min 2473 Max 2503
Avg 2489 S-D 14.4
ES 30

Shot Speed
1 2473 ft/s
2 2503 ft/s
3 2503 ft/s
4 2493 ft/s
5 2476 ft/s
---- ---- ---- ----

Synced on: 2019-02-25 10:33:28
Series 2019-02-25_10_33_28 Shots: 5
Notes 28.0gr 8208xbr
Min 2482 Max 2505
Avg 2490 S-D 9.5
ES 23

Shot Speed
1 2485 ft/s
2 2495 ft/s
3 2485 ft/s
4 2482 ft/s
5 2505 ft/s
---- ---- ---- ----

Synced on: 2019-02-25 10:40:20
Series 2019-02-25_10_40_20 Shots: 5
Notes 28.0 gr.8208xbr
Min 2470 Max 2486
Avg 2475 S-D 6.4
ES 16

Shot Speed
1 2474 ft/s
2 2486 ft/s
3 2474 ft/s
4 2471 ft/s
5 2470 ft/s
---- ---- ---- ----

Synced on: 2019-02-25 10:45:39
Series 2019-02-25_10_45_39 Shots: 5
Notes 43.6 gr H4350
Min 2469 Max 2483
Avg 2478 S-D 5.4
ES 14

Shot Speed
1 2469 ft/s
2 2483 ft/s
3 2477 ft/s
4 2480 ft/s
5 2481 ft/s

I was testing different seating depths this session

Popeye - you mention nothing about barrel length, bullet weight or type. Mind adding that information?

Also, 43.6 grains of 4350 seems to be excessively compressed, from a .308 sized case, or is a typo. I'm guessing typo.