imr8208 question

[hoene72]

Does anyone have any idea were to start with this powder in a 243 ? Want to try it in a factory rifle with a 65 and 75 gr bullets. Also would like to know about data for the 6br norma with 75 and 105 gr bullets .
Thanks for the help

 

[Steve Blair]

IMR 8208 XBR is a little too fast for the .243. It falls between 4198 and 3031, but packs densely. In 6BR, the 75 is a good bet. The 105 is too heavy. Other powders are better suited, like H4895 and Varget.

The Hodgdon Reloading Data Center has a lot of data for 6BR and other cartridges.

 

[jo191145]

hoene

I've been pondering the same question. According to IMR's burn rate chart 8208X is just under H-4895. Theoretically it might be a good powder for the 243 and very light pills. Might be better yet if your using bullet lubes ande like to hot them up. Theres plenty of leftover room in the 243 case.
Its quite possible Hodgen does not agree judging by the absence of data. I might just try a few anyway.

I agree with sleepy. I'm thinking this powder is gonna be just as good if not better in the BR with light to medium pills as it is in the ppc. So far my ppc is liking it just fine.
It just may work with the heavies too. I just read a post on Benchrest Central (centerfire benchrest section)
Seems a fellow went WAY over book data with a 6BR and 108 Bergers. Claims 3100 fps and .25moa at 200yds. I won't post his charge weight. That has got to be a HOT LOAD!!!


Data is available online from The Hodgen Reloading Center for the 6BR.

75gn 28.0 - 30.8max = 3167fps

107gn 24.0 - 26.7max = 2555fps

 

[Steve Blair]

Take a look at my post about QuickLOAD and 8208.

 

[jo191145]

Take a look at my post about QuickLOAD and 8208.

Well I looked. Seems IMR and Quickload do not agree on burning rates. Nothing new about burn rate charts being off.

 

[Steve Blair]

I checked several known good loads against the IMR data and (surprise!) they seem a little conservative. My best Varget load in 6BR is 30.5, a little short of a full case with Sierra 107s seated at 2.385 and no pressure signs. IMR data shows that load at 2.25 OAL as compressed and 29.0 as a max load. As per usual, and what we already knew, use the data as a guide, start low and work up.

QuickLOAD is useful to quickly sort through a variety of combinations and find likely candidates. It is sometimes dead on, sometimes notably off, either high or low. I look for powders that have at least 90-95% loading density at full pressure, show reasonable velocity and burn all or almost all of the powder in the barrel. Otherwise, I treat it just like I would any other data.

 

[jo191145]

Yep, When your running a 6BR to be competitive book data is usually quite conservative ;D
I agree in the 243 theres quite a bit of room left over in the boiler room. Generally not a good thing and potentially scary. Never stopped me before tho ;D

I would/will start with a 58 V-Max. Pop a few downrange to see what happens.

 

[wapiti25]

Burn rates that are from a combustion bomb don't relate to cartridges very good. Combustion bombs work to about 30K not the 40 to 60 that a lot of our cartridges are producing.