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

[JASmith]

Tony / Joe:

It appears that no one is willing to be specific about requirements...

One of the reasons for the reticence is some of us are hesitant about displaying our naivete...

Flip responses aside, you really have made an excellent start. One of my mentors from years ago suggested a spiral approach to getting at a conclusion when the topic is particularly complicated.

Your expansion of Tony's list is something we can work with to spiral in to the specifics. Shotgunning the list is likely to lead to a lot of wandering. I propose that we start with the first item, check for redundancy with other items, and then beat on it until the specificity, testability, and reasonableness tests are satisfied. After that, we tackle #2, and so on. Other items can be added as we work down the list.

So, let's start with #1:

Originally Posted by LR1955
1. To match the retained energy, vertex height and wind-drift performance of the 7.62mm M80 ball round at 1,000 metres.

This is a clearly stated requirement but I would ask what is so important about equaling the exterior ballistics of M-80? If one can only equal the performance, why a new cartridge?

I resonate with Gene's critique on this point, but understand the hesitation to ask for more. The balance of minimum acceptable versus desired performance normally handled in requirements documents by specifying a threshold and an objective performance level. Failure to attain the threshold level means that the candidate is automatically rejected. The objective level is what the requirements team would really like to see within reasonable technical limits.

So, item 1 should have:

• Threshold: At least equal the vertex and wind drift seen by the 7.62X51 NATO M80 at 1000 metres.
  
• Objective: Reduce the vertex height by at least 10% and the wind drift by at least 20% compared to the M80.
  

The 10% and 20% values are place-holders for now. Part of our discussion should explore what is possible within the projected case volume and bullet design limits.

Second, I'm sure that we are tacitly assuming the same barrel lengths in our discussion. We need to specify that so that someone doesn't try to compare the performance of the 7.62 in a 20" barrel with that of the new cartridge in a 14.5" barrel. (Now if we want that we need to so state, but bear in mind the velocity difference puts a significant handicap on any new design.)

I've run out of time for this morning, but we will need to check for redundancy against the 5.56...