Is there any chance that the P-47 load-out can be corrected to 2x1000lb and 1x500lb?

[IceFire]

Originally Posted by Grach

After doing some digging in various books & pamphlets it seems the following .50 BMG rounds were available in WW2:

(In rough chronological order of introduction.)

Ball (B) M2 (mild-steel core) 46g, 858m/s replaced earlier ball (lead cored) rounds and was available pre-war. Mainly used for training during the war although early on in the Pacific it seems to have been used.

Armour Piercing (AP) M2 (hard-steel core) 45.88g, 885m/s proof required penetration of 22mm RHA plate at 91m. Available pre-war, it was used extensively throughout the war until completely supplanted by M8 API.

Incendiary (I) M1 (Phosphorous, mild-steel core) 41g, 901m/s contained 2g of white phosphorous. Available pre-war, widely used until M8 API appears and then to a lesser extent except in Pacific.

Tracer (T) M10 (lead core) or M17 (mild-steel core) 41.67g, 873m/s it was observed that at ranges under 91m the burning trace had a similar incendiary effect as that of the early .30 cal (phosphorous - not Dixon-De Wilde type) Incendiary round. Both available pre-war, mostly replaced by M20 APIT and M21 HT.

Armour Piercing Incendiary (API) M8 (IM fill hard-steel core) 42g, 888m/s contained 0.9g IM (Incendiary Metal) compound. This burned far more fiercely than phosphorous and was estimated to be 2x as effective on a weight for weight basis. M8 API proof required minimum 90-95% of the performance of both the M2 AP and M1 I rounds. This was a pre-war design and was hurriedly put into production after combat reports from Europe were analysed in the first two years of the war. It started appearing in 1942 and was effectively standardised in Europe by the beginning of 1944.

Armour Piercing Incendiary Tracer (APIT) M20 (IM fill hard-steel core) 39.66g, 888m/s contained 0.9g IM (Incendiary Metal) compound. This was the trace partner of the M8 API. The trace cannister meant that the penetrator was shorter and lighter than the M8 API penetrator. It was expected that M20 APIT should penetrate with 90-95% of the M8 API performance however. Developed and issued alongside the M8 API.

Tracer "Headlight" (HT) M21 (lead core) 45.3g, 867m/s designed as a high-intensity tracer, holes in the jacket made the trace visible from all around. Designed and issued starting in 1943 for use by bomber defensive guns. The theory was that it would unnerve attacking enemy fighters as they would see the vivid tracers approaching them. Some incendiary effect noted at close ranges.

Incendiary "High-Intensity" (HI) M23 (IM fill mild-steel core) 33.18g, 1036m/s contained 5.8g of 'improved' IM (Incendiary Metal) compound. This bullet was designed to ignite jet-fuel and by all accounts was extremely destructive. Issue only started during late 1944 though and it was not widespread during the war. IIRC it was only issued in the ETO.

I have some information on belting compositions if anyone is interested.

Also of note is that the .50 BMG was tweaked during the war and it's rate of fire was routinely around 850rpm for unsynchronised installations at the end. (Compared to around 750rpm for pre & early war.) Synchronisation really slugged the rate performance though, dragging it down to around 500-550rpm! I can see why there were so few synchronised M2 installations, but I digress.

Thanks for digging that up. It's the M23 improved incendiary that I was referencing before. Couldn't for the life of me remember what it was called.