...or more correctly the 10th Cavalry Brigade, though often the unit is called the 10th Motorised or 10th Mechanised Brigade. Whatever one calls it, this unit will be well known to gamers of the September campaign. I thought I would offer some suggestions for representing it in BGB, as it doesn't appear in the army lists.
For a platoon of the 10th Mounted Rifles or the 24th Ulhans, the starting point has to be the organisation given in the supplement for a cavalry platoon (p.23). What few sources there are indicate a slight difference in the motorised version. My own reference is the Micromark list for the Black Brigade, supported by some of the posts in this online discussion:http://forum.shrapnelgames.com/showthread.php?t=46272
Platoon HQ - a bit smaller than the cavalry one, with 3 men in a motorcycle combo. Special rules officer, runner.
then 4, rather than 3, 'cavalry' sections, each with 8 men with a wz.28 lmg (i.e. a BAR)
Support options: the 46mm mortar appears to have been absent from these motorised units (as it also seems to have been absent from the mounted cavalry squadrons - a point of disagreement with the lists). So maybe leave this out. On the other hand, in addition to an MMG company within each regiment, each infantry company had its own MMG platoon with 2 wz.30 MMGs. So allow the 'HMG' option to be taken twice. The ATG and Tankette options seem fine as per the cavalry page (p.23). As for anti-tank rifles, one would be an acceptable support option, or it might be more realistic to have one permanently part of platoon HQ, making that unit up to 5, perhaps with another motorcycle for transport or having the whole platoon HQ in a PF508 Lazik.
Transport options would be to lift 2 x 8 man sections in a PF621 or Praga truck, so 2 trucks to lift the whole platoon at a minimum, with platoon HQ on its motorcycles or in its Lazik.
I think the 'Bren' rule would work well with this organisation, allowing the BAR to be split off from the infantry sections when needed.
Tank support would of course be from Vickers light tanks. The platoons were supposed to be 5 tanks strong. The split between mg armed tanks and those with the 47mm gun seems most likely to have been 3 gun tanks to 2 mg tanks. This is the organisation given on the PIBWL military site, which I rate as the definitive online source for 1939 Polish armour. We can also note that of the 38 Vickers tanks the Poles had, 22 were converted to the 47mm gun, with 16 having mg armament, which supports the proportions given above for each 5 tank platoon.
I would add here that I disagree with the AP stats given in the supplement for the 47mm carried by the Vickers tanks. The book gives the guns as L/32, but this is surely incorrect. Check out the appearance of the L/32 47mm on the Somua tank and compare it to the much shorter 47mm in pictures of the Vickers. I would go along with the PIBWL site again and rate the weapon as an L/18-21. AP stats would be 3-3-2-1-1, with HE staying at 3/5+.
The Brigade also had a tankette squadron, so a tankette platoon is fine, but there were no armoured cars in the Brigade organisation. Tankettes should be taken as recce choices, along with infantry sections or motorcycle sections. Recce command would most appropriately be a section in a Lazik car.
Other bits and pieces - the Brigade had a 75mm artillery battery and a 100mm howitzer battery, both of 4 guns. It also had an AA battery of 4 40mm Bofors AA guns. There was a bridging platoon, construction company and engineer platoon, so all these options from the Polish list are available. Regarding a couple of 'unique' SP guns on tankette chassis, don't get confused between the TKD and the TKS-D. The TKS-D is mentioned in the supplement, mounting a 37mm Bofors ATG, but does not appear in the lists. It seems the only 2 TKS-Ds built may have been used in combat in 1939, serving with the A/T platoon of the recce battalion of the Black Brigade. This produces an interesting 'motorised tank hunter' choice under recce support units. Stats would be as for a TKS tankette, but open-topped, armament being a standard 37mm Bofors ATG with 45 degree traverse. The TKD is as given in the lists, being a 47mm SP gun. The 47mm weapon was a wz.25 infantry gun, with AP stats probably falling between the 47mm in the Vickers tanks and the superior 37mm Bofors ATG. I doubt it was an L/45 weapon as given in the BGB lists. The 4 TKD prototypes only had mild steel armour. They might have been used in the defence of Warsaw, but don't seem to have served with 10th Mechanised. Of course, finding models of these 2 weapons is problematic. If anyone knows of either being available in 15mm, let me know!
Talking of Warsaw, there was of course the sister formation of the Black Brigade, the Warsaw Mechanised Brigade. The basic tank, tankette, artillery and infantry elements were the same as for the 10th. There were detail differences in other parts of the brigade, but this post has gone on long enough, so I'll stop there.
Hope this all might be of interest. I strongly recommend both the Micromark lists (http://www.wargamevault.com/browse/pub/3426/MicroMark-Army-Lists
) and the PIBWL site (http://derela.republika.pl/index.htm