Requirements for Replacement of Currently Issued 5.56 M-855 and 7.62 M-80.

[stanc]

Stan, Your post has two paragraphs. One is posed as a question -- I responded to it.

The other question is posed as a statement. I did not address the issue posed there partly because it wasn't a question and partly because the point made is a valid point. My apologies if it's the one you wanted commentary on.

Joe, there was only one question. The second paragraph was just meant to elaborate on the first, in an attempt to make it perfectly clear what my concern was. Obviously I failed in that regard. Perhaps my writing skills are deteriorating from insufficient practice. After all, it has been over a year and a half since I wrote my last magazine article. :o

As for trajectory matching to save money on sights, there are precedents for new loads (e. g. M855A1) mapping more or less into existing trajectory tables. I personally don't like the notion because I believe it to be a false economy compared to what one could get with appropriate ammunition. This is particularly true with optical (vice iron) sights.

Thanks! Now you're providing feedback I was wanting to get.

But, I'm not sure that I'd agree with it being a false economy. Have you seen the prices for military optical sights? List price on the 6x48 ACOG the Brits use on their L129A1 rifle is nearly as much as for the rifle! The M145 Machine Gun Optic is less expensive, but it still ain't something that a fiscally responsible agency would want to discard.

There are also precedents for not matching the existing trajectories when new ammunition types (e. g. Mk 262). The difference is in the role the ammunition is to play.

Yeah, but Mk262 is a special purpose, limited issue load. I think we should be primarily concerned with general purpose, ball ammo.

Even so, the differences in trajectory between the M855A1 and the Mk 262 are small enough that a silhouette will still get hit most of the time with a standard center of mass hold all the way out to 300 meters. (I haven't run the trajectories, but it would be better if someone actually tries it with a rifle sighted in at 25 meters using the M855A1. Then shoot both rounds at 100, 200, and 300 meters using a center of mass hold. The bet I would make is that this has been done. I would wager a little less that my claim is valid!)

No bet here. At 100-300 meters there is negligible difference in trajectories, even between 5.56 M855 and 7.62 M80. It's at 500-900 meters where the difference in trajectories between bullet types becomes very noticeable.

It is less difficult to dumb down a trajectory than it is to make an existing design do better.

Of course.

My vote is for an "equal or better" trajectory for our discussions and let the sighting implications sort themselves out.

That may be a little short sighted. (Pun intended.)

However, I was thinking less about applicability to the discussion, and more to incorporation into a new magazine article I've been contemplating.