303 British box question

I have no idea who this ammo was loaded for or what they are H/S FN 40 with a yellow tip. Are they smoke tracers that are a lot of fun to shoot on a calm day? Thanx

Machine gun cartridge
Do not store in excess of 40 degrees celsius

Not sure on smoke trace?

I believe these were on a contract for the Finnish Air Force.

Thank you for the replies I may have to try a few of these to see if they are smoke tracers. I had a few of them years ago and on a calm day they would leave a beautiful trail of smoke rings.

You ARE going to invite me to that “Trial” aren’t you Gerry???

If these are smoke tracers (incendiary) I’m sure I have read that they are banned in CA. You never know who is watching these forums.


ERIKOISLUOTI=Special bullet

Last two lines: Do not store in heated storages.

Can you post a picture of the headstamp and cartridge?


The purpose of smoke tracer was not the same as incendary although there may have been an overlap in functionality. Smoke tracer was common on aircraft guns to give the pilot visual confirmation of where his shots were going.

So who knows, if you are going to shoot it, once its gone who’s to say?

Smoke tracers are all derivatives of the original Buckingham design whereby the bullet contains phosphorus which is expelled from a weep hole in the side of the bullet during its trajectory and leaves a distinctive smoke trail. The primary intention of these bullets however is the incendiary effect on striking the target. They were originally designed in WWI for the ignition of hydrogen in observation balloons, but later versions (B Mark IV) remained in service with the RAF until about 1943. The smoke trails can often be seen in gun camera film from the Battle of Britain.

The term “Smoke Tracer” seems to have been coined by Kynoch as a trade description of their version of the Buckingham bullet, which was itself subject to several Kynoch patents. The British military never used the term for the Buckingham, always describing it as an incendiary. Normal type tracers were referred to as “Flame Tracers” and these were always preferred by the British for aim correction even in WWI.

Kynoch supplied large amounts of air service ammunition including Buckingham type to Finland and other Baltic states in the period between the wars and I suspect that “smoke tracer” became a generic name for this type of ammunition. Kynoch export packaging for these rounds usually had blue labels conforming to British colour coding and were described as “Mark VII Smoke Tracer” or sometimes “Mark VII Smoke tracer and Incendiary”. A typical headstamp would be “K 27 VIIB”. Example label attached.

However, as these FN rounds are labelled “Incendiary” they may not be smoke tracer/incendiaries. One way to tell would be to pull one and see if there was a soldered weep hole in the side of the bullet below the neck level.

I appreciate this does not directly answer the original post, but it does illustrate the origins of the term “smoke tracer”.