As a "serious" and relatively experienced reloader when working with a new powder in a known rifle: How far above a "book load" would you venture?

Specifically the .223 Rem using 77 grain Siera MK's and IMR 8208 XBR powder.

Book (Hodgdon's website) published maximum 23.2 grains for a velocity of 2792.

The known rifle is chambered in 5.56 Nato.

That's like asking how long is a piece of string. Every rifle is different and as an experienced reloader you should be familiar with what to look for in high pressure and dangerous situations.

quote:

Originally posted by Pegleg:
That's like asking how long is a piece of string. Every rifle is different and as an experienced reloader you should be familiar with what to look for in high pressure and dangerous situations.

Well said, Peg.

Some "books" occasionally list loads that are primer-poppers in certain individual rifles, although most recent manuals tend to be rather conservative in general. There is no useful rule of thumb.

You got some good replies there. The only way you would really know is have pressure testing equipment on "your" rifle to know whether you have tread into dangerous territory. The old suggestion about keep upping your loads in tenth of a grain increments is not fail safe. For one thing you really can't get an accurate reading of pressure from primer appearance. The measurement they recommend is measuring the case head expansion against the measurement of a factory load case head expansion. I say this to you: why do you need to go beyond the maximum load? If you feel you need more velocity from a 22 caliber then buy the next larger round up in that caliber. Also as an analogy do you drive your car everywhere you go as fast as it is capable of doing? No Be safe and load according to the book and even then work up on the listed maximum loads.

I agree with the above..

how many fps are you gaining really, in ratio to the increase in pressure..

it may be okay in a bolt action, but in an AR, how much are you pushing the recoil system and potentially straining it?

if 8208 XBR takes a max charge of 23.2 grains for an MV of 2800 fps or so, with a 77 grain bullet, then evidently its burn rate is pretty much the same as H 322..

I am interested in this subject somewhat.
I bought a pound of this powder to try with different calibers and from what I have read it is not the fastest out there but it seems to be more accurate in various cartridges.
I know it is used as a replacement for benchrest powders that have already been shot to near extinction.

In my 12bv-SS-s I've burned 22grains of 8208 behind a 75 grain bullet driving it at a little over 2800 fps.,with no obvious pressure signs. I never had any load data to work from but judging from the velocity it probably is close to the top.?.? roger

Thanks bartsche.
Every little bit helps.

quote:

Originally posted by bartsche:
In my 12bv-SS-s I've burned 22grains of 8208 behind a 75 grain bullet driving it at a little over 2800 fps.,with no obvious pressure signs. I never had any load data to work from but judging from the velocity it probably is close to the top.?.? roger

If it's a 223 the top load (according to just one reference...Hodgdon) it's 22.7 grains for around 53K pressure.

1/10th grain over .223 maximum, but fired in a 5.56 Colt 6724, yes 300 yards