Calibration & Reference Components

One more time, with clarity.

We have discussed this before. I went back and re-read the most recent threads and I’m still not certain that I understand Calibration and Reference Components. Can somebody put it in simple, everyday, farm-boy language for me.

Reference - I believe that these were intended to give to contract suppliers as a “reference” or model for what the end product was to look like. Right or wrong?

Calibration - To be used by manufacturers to “calibrate” certain machinery. But what machinery? And how were the Calibration components to be assembled into Calibration Cartridges or were they two seperate and distinct items?

Boxes - Why the unusual boxes, such as the 30 round box shown here? Was it a standard size box from some other use that was simply utilized? The one here has some added coardboard fillers so it obviously was not made to hold thirty 7.62x51 cases.

Any answers, even if they’re simply guesses?


My 2 cents which may well be wrong & I’m hoping like you Ray, for someone to provide the full & correct information.

Reference- To be held in house, to provide a “reference” to check further production aginst.

Calibration- Not for calibration of machinery but a “bench mark” of the component(s) and when fully assembled used in testing aginst production lots. So - making sure production levels fall within the accepted calibration tollerances. (not sure I said that very well)

5 October 1984


This specification covers a Cartridge, 5.56MM, Ball, (Heavy Bullet) Reference to be used for calibrating, proof testing, and inspecting equipment for the performance tests of the Cartridge, 5.56mm, Ball, M855, and Cartridge, 5.56mm, Tracer, M856.

With some of the equipment I have had experience with in the past the folowing was correct.

The calibration device was set towrds the closest tollerance. This is what you set your equipment to as it wore to a larger dimension. (example overall length no shorted than this)

The fererence was a maximum tolerance. ( example overall length no greater than this) You used this device used to compare your finished product to.

I am however only assuming this is correct with the ammo indusry also.


Pete, Daniel, Doug

Thanks. Every little guess helps.

Since all of the FA Calibration and Reference cartridges and components, that I have seen, appear to have a “Y” in the lot number, that must be a clue of some sort. It probably remains for HWS III to tell us what the “Y” means. I’d guess it’s some sort of internal FA designation. (During WW II FA used a “Y” designation to replace the “E” but that was short lived because it was too confusing.) I’ve never seen it listed anywhere.


From the Mil Specs I’ve read, the Reference ammunition was meant to be fired. They have accuracy, velocity, and pressure specifications.

The information I have had has always been that our “Reference Ammo” is what England calls “Ballistic Standard,” and that they were made for testing firearms so that the ammunition would not be suspect in any malfunctioning of the weapons tested, being carefully loaded to proper pressures, velocities, case and bullet measurements, bullet ogive, etc. etc.

I could be wrong. It is just what I was told when I got my first Reference box of .45 (Still full, as the cartridges have zero identity outside of the box, and therefore were not even of enough interest of themselves for me to slip one into my singles collection, since I have the box), and have been told again many times in suceeding years.

I can’t say for Calibration components.

Thanks John. Every bit helps.

Being ever inquizitive I put the cases to the Benchrest shooters test - I weighed them for consistency. I had an opened box of thirty 7.62x51 Reference, hs FA 60, and a box of twenty Cal 30 Calibration, hs FA 46.

The 7.62x51 cases had a variation of plus or minus 1.15%. The Cal 30 cases were even better with a variation of plus or minus 0.95%. Even by Benchrest standards those are very good cases.

50 cases is not really a laboratory type sample but if they are even close to being representative of both Reference and Calibration components, FA did a very good job.


Found at : … Portatives

Reference cartridges system

In order to solve the problems of conflicting industry standards, efforts are currently made to produce a notion regarding “reference cartridges” similar to the system used by NATO armies (NATO EPVAT testing). In this system every manufacturer has to set aside a batch (also named “lot”) of ammunition they consider to be of very good quality and representative of what they need to produce later. This batch is sent to the C.I.P. proof houses and to SAAMI approved centers where “reference firings” are performed. The results of the reference firings are recorded and published. A number of these reference cartridges are distributed among all C.I.P. proofing houses and SAAMI approved centers for later use. Then, when a new ammunition batch (lot) arrives to be tested, the proof-house or shooting range fire a set of 20 reference cartridges to see how they behave with the local equipment and with the current atmospheric conditions. Results are then compared to the reference values as published and correctors (delta values) are computed. Then, the current batch (lot) ammunitions are fired and the correctors are applied on the measured value giving a result “comparable” to the reference itself. This procedure is very accurate, almost not disputable but more complex to perform than the procedures used up to now by C.I.P. and SAAMI. It requires the use of a computer connected to the measuring instruments.

Here is a box of

… And a couple more!