Originally Posted by colodog
Another vote for, Use a Chronograph!

Look at it this way, the book says they reached max pressure with ABCD load, producing XXXX speed, in their rifle.
If you're not using the same primer and brass as the load manual it's not really the same load.
If you can't measure velocity, all we, or you can do is guesstimate.
Barnes bullets recommends their bullets be seated +-.050" off the lands for a running start, something to check.

Military brass is usually heavier and won't hold as much powder as commercial brass so dropping one grain may not be enough, I don't know!
You'd need a Chronograph to compare a single load between military and commercial brass. (I'll be checking 30-06 myself)

Lastly, your buddy's M855 ammo wasn't shooting monometal bullets which are usually longer than lead/steel core but you can't compare velocity anyway without a Chronograph.



Although this is true for the 308 and 30-06 Military Brass, it is not true for the 223 vs 5.56 brass.

In fact most military 5.56 brass has More case capacity then civilian 223 brass.

Note in this chart the Military brass had the highest capacity.

[Linked Image]

...and this from Sierra.

The conventional wisdom to reduce loads with military brass is familiar to most reloaders and is generally good advice. The rationale here is that the military cases tend to be somewhat thicker and heavier than their civilian counterparts, which in turn reduces capacity and raises pressures. This additional pressure normally requires a one or two grain reduction from the loads shown in most manuals or other data developed with commercial cases. While this is most often the situation with both 308 Winchester and 30-06 cases, it is less true with the 223 brass. We have found that military cases often have significantly more capacity than several brands of commercial brass. Again, take the time to do a side-by-side comparison of the cases you are working with and adjust your load as needed. There may be no need for such a reduction with the 223. Know your components and keep them segregated accordingly.

http://www.exteriorballistics.com/reloadbasics/gasgunreload.cfm

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