M855A1 62gr 556NATO, M80A1 130gr 762NATO, M80A1 derived 150gr

Last crawled date: 1 year, 11 months ago

The M855A1 and M80A1 bullets for 556 and 762 caliber. .223 and .308 projectiles.

.224" and .3086" as bullet diameter. Sources: "Hatchers Notebook" page 15, and https://en.wikipedia.org/wiki/.223_Remington .

The M80A1 was drawn first. I used the "g73" file and a photo of a bullet that was cut in half. I came one 149.96 gr, to me thats right about 150 gr, so that is right in the middle of most bullets for 762NATO. So it should work fine. But it was not the 130gr talked about in articles. So i looked further.

I found some files on websites, with all the info i needed. I found that .733 inch for the penetrator made it to long to look like the cut in half bullet, weight wise the bullet would be to heavy if i would have done that. So the penetrator ended up being a bit shorter. The final weight: 131.84gr, so thats right about 130 gr. It should work fine, and do "its thing", that is; shatter on impact with the perpetrator flying straight bending of, and the core flying more straight making a really big wound cavity right after impacting.

The M855A1 did not have so much information on it. It was noted on websites it was about 1/8 inch longer than greentip bullets, and 62gr. The bullet diameter being .224", armed with some cut in half bullet pictures. I went on to draw this thing. The bullet ended up being 1.01" long... Really American of course... The weight being 62.33gr in the end, that confirmed the length and shape to me. It is a devastating bullet with great terminal ballistics and a higher ballistic coefficient.

All the bullets are fitted on 556NATO and 762NATO brass. Drawings are added in the files.

The bullets have their material added in solidworks, exept the penetrators, i chose 1020, or regular steel. In the adds there is a post with the chemical composition of the penetrators. You could look for the proper steel type, and add the weight to Solidworks. That is what i did with all the other components of the bullets and that gave me their weight, and the center of gravity. That is what you need for the following books:

I also added "Modern Exterior Ballistic" by "R. Mc Coy" and
"Theory of the Interior Ballistics of Guns" by "J. Corner", so you can fool around with the ballistics of the rounds, and make those fancy curly diagrams as listed on page 236 of Mc Coys book, also listed in the "Public Release EPR" file.

I advice you to use a copy of "Maple" Math program, or a similar program for all the formulas, otherwise these formulas dont make sense at all...

Good luck with your bullets! If you want to know how these are made i refer to my earlier upload: https://grabcad.com/library/7-62-nato-bullet-factory-cartridge-case-feasibility-study-1

Next upload will be: 300Blackout, 6.5 Creedmoor, 45 Raptor and .22TCM, all 556NATO and 762NATO derivatives.
M855A1
https://www.youtube.com/watch?v=d8IvDPuVuho
https://www.youtube.com/watch?v=fX4ODh1g4eM
M80A1
https://youtu.be/yW-jlvNQA8w
https://youtu.be/aH_gijsxr9E

Note: These rounds still perform subsonic, and thus at extended ranges if shot supersonic at full speed.