Headspace and Timing

[KenWats]

First time I saw it done was in ROTC, and my recollection is about the same as Pete's- the NCO showed us how, but I didn't get a warm fuzzy on how to do it and I didn't get any hands on (although I know I wasn't complaining at the time, I was freezing my butt off). Later, as a PL, I made my squad leaders teach me how to do it, but I don't recall having to ever do it myself (I had a good track driver who took care of it before the LT could mess it up).

[Stan]

Pete, From way back when and then some

The posts start here.

In the 70's at MacGregor Range (Ft. Bliss) just about every swingin' Delta had all three of these "tools" on him while operating the M2. Sadly, few actually knew the difference .004 (four thousandths of an inch) would make in head space (NO GO is .206 and GO is .202) and what .002 would do to the timing on either the .50 or .30 BMG.

The demo pocket knife almost worked for head space and the P38 was just .002 too much for timing FIRE for both the .50 and .30.

For some strange reason, the real head space gage and pair of timing gages were simply too difficult to use

BTW, the demo knife is not pure stainless and one should not use it for EOD work.

[Fuchs]

You guys still don't have the Fabrique Nationale Herstal quick change set that eliminates the headspace issue?

IIRC four of five such sets were developed decades ago by different companies, even including U.S. companies.

What`s your military budget? Half the world's military spending?
Still suffering from a 1919 machine gun design flaw???


edit:
globalsecurity.org says

The M2E2 Quick Change Barrel (QCB) Kit enhances the M2 with new features and design improvements that make the weapon easier and safer to use. The kit features fixed headspace and timing reduce the time required to change the barrel and eliminate the need to reset headspace. The quick change barrel itself has a removable carrying handle that provides soldiers with a more expedient and safer way of changing barrels. The barrel also has a flash hider that reduces muzzle flash, making the M2 night friendly. The kit was incoprorated into the type standardized M2A1 design, which also featured a modified bolt and trigger block. By Spring 2011, all new production weapon were to be built to the M2A1 standard and older weapons would be retrofitted witht he QCB Kit.

http://www.globalsecurity.org/milita...d/m2-50cal.htm

[Stan]

You guys still don't have the Fabrique Nationale Herstal quick change set that eliminates the headspace issue?

IIRC four of five such sets were developed decades ago by different companies, even including U.S. companies.

What`s your military budget? Half the world's military spending?
Still suffering from a 1919 machine gun design flaw???


edit:
globalsecurity.org says


http://www.globalsecurity.org/milita...d/m2-50cal.htm

Fuchs,
In principle the design seemed to be good and the E2 versions tested at APG, MD puportedly saved 10 minutes on a hot barrel change. But, most of us that trained and regularly qualified with the M2 can perform an HST (or HS&T) in less than a minute. The differences in barrels are ever-so-slight, that a seasoned marksman can be up and firing in less than a minute.

There are a number of issues that Global Security doesn't cover at the link such as Safety of Use Messages (SOUM) 06 and 07 from TACOM (AKO login required).

In short, and much like most SNCOs believe, this seems to be a training deficiency combined with money-hungry companies than a problem with the BMG.

I'd say keep it simple (KISS)

Going by feel is always a bad idea though it will work.

Yep, concur. Then there's this...

Spin the barrel in and back off two clicks.
A dime and a nickel can be used as field expedient gages.

And for timing you would then use what?

How many E-1s have a dime and a nickel at the end of the month?

[EPA]

Not to mention if you have a head space and timing gauge in an Inf Bn you're a lucky man. Those are worth their weight in gold in Weapons Co.

Pete

[Fuchs]

Less than a minute? How much less?
Changing the barrel of a MG 3 takes ten seconds at most (if you keep a minimal target silhouette). That's a 1942 solution and already outdated as quick change barrel concept.

A barrel change of more than 20 sec effectively denies a barrel change in many if not most combat situations.

[Pete]

Pete, From way back when and then some.

Thanks, I looked at the older thread. I wonder what Schmedlap is up to these days and I hope he's doing OK. He's a no-BS soldier's soldier, emphatically not a careerist or feather merchant.

[Cavguy]

In the Armor/Cav community a H&S gauge is pretty much found on every vehicle commander and gunner. Big deal if you blow the cover off and didn't check the H&S!

That said, H&S is usually set in the beginning and verified as part of Pre combat checks prior to roll-out.

[Pete]

That said, H&S is usually set in the beginning and verified as part of Pre combat checks prior to roll-out.

In retrospect that's something I should have been doing as the XO of a four-gun 175mm battery in 1980. The four M548 tracked cargo carriers in the firing battery had M2 .50-cals. Our main concern at the time was keeping the 175 rounds within 50 meters of our targets.

[Stan]

In retrospect that's something I should have been doing as the XO of a four-gun 175mm battery in 1980. The four M548 tracked cargo carriers in the firing battery had M2 .50-cals. Our main concern at the time was keeping the 175 rounds within 50 meters of our targets.

Jeez, Pete, don't you mean the M35 Deuce and a half? I only know of one other person herein that drove the M548 when Christ was a Corporal (Ken)

With that, a little history...

INTRODUCTION
The author’s introduction to the “fifty-cal” was the opportunity to fire a few rounds for familiarization during infantry training in 1967.

That was after we had been shown the basics of its operation: how to load, cock, fire, and clear it. Such was the extent of our exposure to the legendary “MaDuce,” officially known as “Machine Gun, Caliber .50, Heavy Barrel, M2.”

The instructor explained that the M2 had been in use since 1933. Some of the trainees, including myself, gazed curiously at the guns placed before us, thinking that they didn’t look that old.

Observing a US mechanized rifle company “trim the tree line” with a dozen “fifties” made me appreciate that the receiving end of such fire was a place no-one would want to be.

[Pete]

In his book Mounted Combat in Vietnam Donn Starry said the Cambodian incursion couldn't have taken place without the M548 hauling cargo but that the vehicle had reliability problems. Based on my experience with them I agree wholeheartedly regarding the maintenance headaches. Ours in 6/9 FA in Germany had ring mounts for the .50 cals.

[KenWats]

Jeez, Pete, don't you mean the M35 Deuce and a half? I only know of one other person herein that drove the M548 when Christ was a Corporal (Ken)

Hah, now you know three. I had an M548 in my Combat Engineer platoon in 1997 (used as a Volcano carrier). Generally referred to as the "Short bus" (I'll leave it to folks here to debate whether that was aimed at the vehicle itself or the operators).

[Pete]

Jeez, Pete, don't you mean the M35 Deuce and a half?

Back when we had the Deuce and a Half our rifles were of .45-70 caliber and our politically incorrect C Rations still had cigarettes in them.

[Stan]

In the Armor/Cav community a H&S gauge is pretty much found on every vehicle commander and gunner. Big deal if you blow the cover off and didn't check the H&S!

That said, H&S is usually set in the beginning and verified as part of Pre combat checks prior to roll-out.

Thanks, Neil (never could get your name spelled correctly)

Something about all those fancy (ahem) upgrades to replace HST training (and result in death). Great video of what often means blowing the top cover off.

BTW, you may be the only person colder than I am here

[Cavguy]

Thanks, Neil (never could get your name spelled correctly)

Something about all those fancy (ahem) upgrades to replace HST training (and result in death). Great video of what often means blowing the top cover off.

BTW, you may be the only person colder than I am here

Thanks Stan.

Alaska is warming up, high's in the 30s this week. Breaking out the shorts after the -40 degree spells of Nov-Jan.

Actually lost most of my acclimatization while at NTC during Jan and Feb, and then some pre-deployment block leave to Hawaii. Rolling out the door to Afghanistan with our unit in the next month.

Niel <==