Estate sale turned up unknown 20 cal vietnam era? RA 65


I obtained some empty brass cartridges at an estate sale that I believe are factory rejects or I believe these were pulled from the assembly line, possibly due to an inspection and defects found. They do not have the primmer flash hole in them and some have nicks and dents. I have many caliber cartridges like this that were also obtained at the Estate sale. One that sticks out and I cannot Identify is a case without the primer flash hole that is smaller in diameter at its base than a 223(5.56) and appears to be 20 caliber. It is stamped “R A 6 5”. I have several of them and I also have some 5.56 that are stamped “R A 6 6” which do not have their flash holes but have bullets seated in them. Did Remington attempt to develop a 20 caliber round for the government to use during the Vietnam conflict? I have never seen a cartridge matching the dimensions of the little 20 cal. round. If my eyes are not deceiving me, I measured a primer pocket at .137"; the base of the shell at .332"; the body, just below the shoulder is .321"; case neck length .285"; outside neck diameter is .237"; and inside neck diameter is .212". Any idea what I may have?

PS: Forgot to say that the cases measure between 1.782 and 1.80 in length. I have 5 of them. Most are around the 1.80 length.
Here are pictures of the 20’s beside the 5.56.



Welcome to the Forum. Here is a link to a post on the XM216 with “RA 65” headstamp: viewtopic.php?f=8&t=13006

There are several other posts on the subject of these and other flechette rounds such as the XM144.


The pics of the XM144 look familiar but what are the case dimensions? They are saying 5.6 mm?? My cases are not that big. Dave, what did the weapon look like that fired these little rounds??
Any pictures?


There was an entire book about the different flechette cartridges. It is not a simple task to describe the cartridges and weapons because there were so many of them.

The book is SPIW - The Deadliest Weapon That Never Was, by R.Blake Stevens & Ed C. Ezell. I don’t know if there’s an on-line version that you can download. Most of us collectors have the hard copy.

SPIW is an acronym for Special Purpose Individual Weapon.


An on line copy of SPIW - The Deadliest Weapon That Never Was is available here: … -Never-Was


I believe the dimensions you give are consistent with those of the XM216 other than neck dimensions and case length. That variation could well be due to the fact that your cases are unfinished as indicated by a lack of flash hole and fairly wide range of case length. There may be other varieties with that headstamp, but that is my best guess. Ray will set me straight if I speak without sound judgement…


Dave is correct.

The XM144 was a first generation cartridge. Headstamps of 62, 63, and 64 are those most often found. The XM216 is second generation. A headstamp of RA 65 is commonly seen.

I don’t remember if the book gave cartridge dimensions. It’s been a long time since I read it. But:

XM144 base diameter is .307", shoulder is .290", length is 1.730", neck diameter is .235".

XM 216 base is .331", shoulder is .318", length is 1.730", neck diameter is .235".

All dimensions approx as measured from a single example.

The XM110 and XM645 are completely different cartridges. Belted cases. Longer. A different primer/ignition set-up. The XM144WE4 is similar to the XM144 but a little fatter.

You need to read the book.

OK guys,

Thanks a million for all the replies. I will read the book, online version. I agree that the case neck length was not “finished” to the specs of their design. That explains the variables in the length as they were probably pulled from the production line, possibly due to inspection or “quality control”. Looking at all the diameters Ray has posted I now believe what I have are unfinished xm216’s. My measurements and those posted of the XM216 are very close. AND my eyesight isn’t what it used to be. I still refuse to replace a battery in my digital calipers every time I wish to use them (seems like) so I’ll stick with the analog dial type.

Again, thanks for all the help AND thanks for welcoming me to the forum.
I’ll dig into my ammo collection and see what else I can come up with! HAR!
Happy Independence Day to ALL


Don’t apologise for your eye sight. Mine can’t be any better. ;-)

The dimensions I gave are from one lone example and an average of several cases could be different.

We’d certainly like to see any other cartridges from your collection that you think would be of interest. There’s not a cartridge that someone on the Forum does not collect and you’ll always find us interested.


Thanks Ray!