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1,901 Posts
Discussion Starter #1
New load data for you today. As I said in my last thread with IMR 8208XBR, I wanted to get a base line for this powder using 147 gr FMJBT bullets so I can adjust for different grain bullets. I still need to work the load up some more to produce velocities close to that of PMC or Federal XM762D. This would be around 2600-2650fps without over pressure of the chamber or port. Last load was at 42.5 gr at an average of 2544fps with no pressure signs. Will have more data for you in two weeks.

Heres what was used.
Socom 16 Rifle
Winchester 147 gr FMJBT bullets (shapes varied)
IVI once fired brass
IMR 8208XBR powder
CCI BR2 Primers
Case length; 2.005"
COAL; 2.775"

40.0 gr.
Lo; 2328fps
Hi; 2425fps
Av; 2374fps
ES; 96.59fps
SD; 37.93fps

40.5 gr.
Lo; 2384fps
Hi; 2420fps
Av; 2398fps
ES; 3575fps
SD; 12.08fps

41.0 gr.
Lo; 2420fps
Hi; 2498fps
Av; 2465fps
ES; 77.93fps
SD; 30.18

41.3 gr.
Lo; 2424fps
Hi; 2503fps
Av; 2473fps
ES; 78.70fps
SD; 31.12fps

41.6 gr.
Lo; 2493fps
Hi; 2512fps
Av; 2503 fps
ES; 19.14fps
SD; 6.7fps

41.9 gr.
Lo; 2485fps
Hi; 2522fps
Av; 2502fps
ES; 37.28fps
SD; 16.00fps

42.2 gr.
Lo; 2509fps
Hi; 2547fps
Av; 2528fps
ES; 37.50fps
SD; 16.7fps

42.5 gr. (only made two rounds, will start next test at this load)
Lo; 2535fps
Hi; 2555fps
Av; 2544fps
ES; 19.80fps
SD; 13.45

I did survive my first squib today. Stayed up too late last night to make some ball powder loads from pulled Georgia Arms bullets. Had a round with no powder inside. cleared the case thinking it was a magazine I was testing and the next round hit the bullet and did not close the bolt. I carry a one piece 18" SS rod in my rifle case and tapped out bullet. Need to Keep sharp when reloading!

Weather permitting, in two weeks I will try to get to my target velocity, and will keep you updated.


2,405 Posts
Looking forward to your follow up. I noticed that Hodgdon places 8208XBR's burn rate right between AA2460s and 4895. Seems like this powder should have some good possibilities.

166 Posts
I just worked up a load to compare the 8208 to the imr 4895. Using the same everything except for the powders, this is what came out of my socom 16.

Brass- Federal 762M1A/ FC/09, 2nd firing
Bullet-Sierra 155 gr. Palma Match HPBT
Primer-CCI 34
Charge- 40.5 gr
O.A.L- 2.847 ( .030 clearance in mag )
Ogive length- 2.262 ( .072 jump)
Taper crimped
Oehler 35 chrono @ 10feet to start screen ( worth the 4 month wait ! )

With IMR 8208 XBR: 20 rd test
2496 H
2397 L
2391 AVG
34 SD

With IMR 4895: 20 rd test
2375 H
2178 L
2263 AVG
SD went out the window because I did not reset from the previous string. Thought hitting the summary reset it. Sorry I'm new at this!

Keep up the good work Glenn! I always look forward to your research feedback. Good to hear you did'nt get hurt.

1,901 Posts
Discussion Starter #4
Keep up the good work Glenn! I always look forward to your research feedback. Good to hear you did'nt get hurt.
Thank you TonyMo, One more blessing to be thankful for this Thanksgiving.
The IMR 8208XBR looks like a promising powder. I went with the CCI BR2 primers because of IMR 8208XBR being faster and builds up pressure quicker than IMR 4895. I have been trying to find where it sits exactly on the burn chart. On some burn charts it sits right above H 4895, but Ramshot Tac also sits there on other charts. I have yet to see a burn chart that has both IMR 8208XBR and Ramshot Tac on them. I may also put a few rounds together with the GGG once fired brass I have. That will give me a little more case pressure( hard brass) and see what my limits are.

Thanks again,

1,901 Posts
Discussion Starter #5
Update... Load testing IMR 8208XBR and 147 gr. FMJBT bullets.

I was able to reach my goal velocity of 2600-2650 fps with out over pressuring my Rifle. Primers are flat with rounded edges, and no cratering of the primer strike. The primers look like PMC and Federal after firing. I figured about 43.7 grains would get me to my target velocity, so I stopped there.
I did start this round of tests at 42.5 gr. of powder since I had only made two rounds of that weight the last test. I also did three strings of GGG brass from 42.2-42.8grains, so lets get to it.

Rifle; Socom 16
Winchester 147 gr. FMJBT bullets (shapes varied)
IVI brass, new
IMR 8208XBR powder
CCI BR2 primers
Case length; 2.005"
C.O.A.L.; 2.775
Slight kiss with a tapered crimp(i did the last ones like that but forgot to add it.)

42.5 gr.
Lo; 2496fps
Hi; 2562fps
ES; 66.8fps
SD; 24.67fps

42.8 gr.
Lo; 2522fps
Hi; 2558fps
Av; 2544fps
ES; 36.26fps
SD; 12.16fps

43.1 gr.
Lo; 2560fps
Hi; 2615fps
Av; 2581fps
ES; 54.22fps
SD; 19.67fps

43.4 gr.
Lo; 2596fps
Hi; 2636fps
Av; 2607fps
ES; 40.15fps
SD; 15.09fps

43.7 gr.
Lo; 2584fps
Hi; 2628fps
Av; 2610fps
ES; 43.76fps
SD; 16.27fps

GGG brass
42.2 gr.
Lo; 2450fps
Hi; 2530fps
Av; 2484fps
ES; 79.41fps
SD; 27.34fps

42.5 gr.
Lo; 2476fps
Hi; 2541fps
Av; 2505fps
ES; 65.02fps
SD; 22.89fps

42.8 gr.
Lo; 2550fps
Hi; 2576fps
Av; 2565fps
ES; 25.51fps
SD; 10.63

Theres a different velocity curve with the GGG brass. At 42.2 and 42.5 grains it has less average velocity than the IVI brass. At 42.8 grains the GGG brass over takes the IVI brass in average velocity. Interesting....
At 43.4 grains the average velocity was on par with factory PMC ammo. I do not wish to push the pressure envelope and try to reach factory Federal XM762D ammo at 2654fps average.
I hope this information helps.
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