1.5"/1,5 Caliber/38mm Flare Help?

I just dug out my British 1.5", No4 Mki* Aircraft Flare Pistol, and noticed the short chamber: 1 5/16" in a 4" barrel.

My ONE kilgore No. 52 fits, but wiggles around just a tiny bit, and my modern, reloadable, polymer case round also fits, (closed on this round in the last photo), but…

… I have noticed that some 1.5" flares have a slightly larger diameter base that extends above the rim, sometimes to about 2 inches, which prevents them from chambering in several 1,5" flare guns.

I have a Sedgely, 1 5/16" chamber, & an International, 1 5/16" chamber, that the two flares shown willl not chamber in.

They will, however, chamber in my Signal Pyrotechnic, bored through with no distinct chamber, and my Kilgore, with a 1 5/16" chamber, (which are otherwise the same design), just fine.

Then there is the Federl Laboratory Gas Gun, 1.5 Caliber, which is also bored through, and has accepted every 1.5" flare/smoke/teargas shell that has been put through it.

So, my ultimate question:
Is there something/someone/somewhere that has good, hopefully detailed, information on 1.5" flares and/or chambers, and differences in rounds?


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The British No4 Mk1* does not have a short chamber but has a ring with 3 raised sections .
Must be to stop the case falling out when used in aircraft. This would possibly put lines on paper case walls too when chambering and visible after firing?
I have one with this ring removed also and it is a straight bore, no chamber.
Fits all British 1.5" shells.

It is the USA Kilgore etc with brass and alloy barrels that I find the British shells will not chamber in.
I think this is why USA shells are called 37mm? Differences in diameters to be noted.

O.K., taking a closer look with my finger, I do ‘see’ the ring milled into the barrel, but not anything that looks like “3 raised sections” ever existed in my Mk4 No 1*, shown above. The ‘chamber’ and ‘bore’ appear to be the same diameter.
Looking closer at the others, the Sedgeley [steel bbl], International [steel bbl], and Kilgore, have a distinct chamber, (like that of an autoloading pistol), before the larger diameter bore.

Any suggestions for where one might obtain 1.5" flares, & find detailed information on them?

Here is a better photo of the inside barrel of the No4 Mk1 (no safety) and Mk1* (with safety).
It shows a slot in the ring and the three raised dimples. Your pistol is like one I have with the ring removed and has just the groove about 1.2" from the breech.
I am pleased to see some interest in flares and signal pistols. I never fire any of mine.
It does chamber the current aluminium 38mm flares by PW (Pains Wessex) and others .

I only see the 26.5mm on the PW web site.

We have a few Flare Gun collectors in my gun club [Virginia Gun Colectors Association], and a couple of us shoot them, when and where we are able to.
I have 5 to 7 [?!] 1.5" including the Fed Labs rifle version, 3 to 5 26.5mm,and one 25mm French made pistol with US markings, dated 1917 [which needs a new mainspring].
I recently picked up a case of 26.5mm, because one never knows when one might have the need to launch a barrage of light, does one?
I have a few of the German Rocket Assist Fin Stabilized 26.5 left, but I will say be cautious when you fire one of those off, especially if you have hair you do not want to loose!

Badgerjack, I have a whole bunch of 37mm and 1.5inch flares and flare launchers for sale if interested.

Jack, not sure if I got it right but the crates you are showing are Czech.

That is correct.
Label inside lid:

Flare Packs, Green, Red, Red 3 Star:

Individual pack label:

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Definitely interested, PM sent.