EmericD said:

The current SOP with the 5.56 mm M4 is to fire only semi-auto, so I'm not really sure that full-auto firing behavior of the XM5 was something of real interest for the US Army. There is the XM250 for that job.

Butt SOP for the battle rifles and the FG 42 has been to fire semi auto allmost all the time as well. For full auto there have been LMGs and GPMGs. So it is as I say: the argument these rifles are "uncontrollable" in full auto is not valid.

EmericD said:

That could mean that full-auto firing with the XM5 will be of limited interest,

Again exactly how it has been in the past.

mpopenker said:

You see, the XM5 has a barrel almost twice shorter than a typical 7.62x51mm "battle" rifle, which means much greater bullet acceleration, and more sharp recoil impulse / higher peak recoil force, even if the total ME is about the same.

So you say the XM5 is worse than the old battle rifles or the FG42?

Please just let us know when you're taking pre-orders for TFW, 2nd edition.

schnuersi said:

So you say the XM5 is worse than the old battle rifles or the FG42?

I've never shot an FG-42 or XM5, and the closest thing that I fired in bursts was the AK-308, but I expect the recoil of the XM5 to be more brisk and sharp, and thus less comfortable to the shooter, especially without the thick clothing and/or body armor

EmericD said:

That also highlight the benefits of the .276 Pedersen, which was 25% lighter (with less recoil) than the .30-06 M2, while delivering the same amount of energy at medium & long range... a truly missed opportunity.

Emeric, do you happen to know how the BCs of the .276 Pedersen compared with the .303 Mk VII (flat based) and Mk XIII (boat tailed)?

dskellogg said:

Please just let us know when you're taking pre-orders for TFW, 2nd edition.

It will be a while yet.... with Autocannon now launched I am working on the compilations of my various presentations and articles, suitably updated. Next will come TFW for which I have already done a lot more research. 

autogun said:

Emeric, do you happen to know how the BCs of the .276 Pedersen compared with the .303 Mk VII (flat based) and Mk XIII (boat tailed)?

Hi Tony,

According to the data found in Jochem's book, the BC of the .303 Mk VII was around 0.211 (G7) in the supersonic domain, and 0.265 (G7) for the MkVIII.

The BC found in Hatcher's book for the .276 Pedersen was 0.247 (G2) which is equivalent to... 0.247 (G7) between 0 and 800 m, when launched at 820 m/s.

By the way, the current 6.8x51 mm Training Practice proposed by SIG (.475 G1 or 0.242 G7 between 0 and 800 m when launched from the XM5 at 808 m/s) is the ballistic twin of the .276 Pedersen when fired from the .276 Garand.

EDIT : and the .276 Garand is reported to have only half the recoil energy of the .30-06 Garand.

Thanks Emeric, that's very interesting. The Pedersen may not have been a perfect general-purpose small-arms cartridge, but was seemingly better than anything else around at the time.

It's an obvious choice for the revised TFW. Of course, there were no talented gun designers in the UK in the mid-1930s, but the best approach would be to give FN and CZ detailed specifications plus large quantities of .276 ammo, and see what they came up with.

autogun said:

but the best approach would be to give FN and CZ detailed specifications plus large quantities of .276 ammo, and see what they came up with

Anything you outsource to Belgians or Czechs will be automatically available to Germans by 1940, if not earlier. Including machinery, complete drawings etc. Especially Czech.

autogun said:

...the best approach would be to give FN and CZ detailed specifications plus large quantities of .276 ammo, and see what they came up with.

Is there some reason to think that that either FN or CZ would have done anything other than adapt their latest designs to fire .276 Pedersen?