Accuracy Standard for M1 Rifle Firing M2 Ball?

[Bill*B]

In "The Book of the Garand", page 277, Maj. Gen. Hatcher states: "In the spring of 1948 ... U.S. Rifle, caliber .30, M1, No. 3,595,949 was fired for group with 1939 Frankford Arsenal M1 ammunition. The 10-shot gave an extreme spread of 14 inches at 200 yards. On June 8, 1948, this rifle was taken to Quantico by a party of Ordnance officers and engineers, and Master Sergeant McKinney worked over the rifle while the group watched. The rifle was then fired by two members of the party, and each one obtained 10-shot groups at 200 yards which gave an extreme spread of 6.75 inches, or less than half the previous group size."

[mac1911]

In "The Book of the Garand", page 277, Maj. Gen. Hatcher states: "In the spring of 1948 ... U.S. Rifle, caliber .30, M1, No. 3,595,949 was fired for group with 1939 Frankford Arsenal M1 ammunition. The 10-shot gave an extreme spread of 14 inches at 200 yards. On June 8, 1948, this rifle was taken to Quantico by a party of Ordnance officers and engineers, and Master Sergeant McKinney worked over the rifle while the group watched. The rifle was then fired by two members of the party, and each one obtained 10-shot groups at 200 yards which gave an extreme spread of 6.75 inches, or less than half the previous group size."

Well what did Master Sergeant McKinney do to that rifle. See they where already using the better ammo M1 ball. In the article do they mention they used the same ammo from the same lot. Or did they use ammo that Quantico had on hand. Generally facilities had the better lots of tested ammo for testing.
Where the shooters the same at each test run?

[country gent]

One of the old tricks was to "shim" the receiver into the stock with cardboard and paper shims for a tighter fit along with under the trigger guard. Another was to peen on side of the gas cylinders splines to tighten them up, This made the gas cylinder a tight light press fit taking wobble out of the front sight. The fit and ease of movement of the op rod affects accuracy of the rifle a lot also. A well fitted op rod with no spring should open and close of its own weight by tipping up and down 60*. There are some things on the hand gaurds also. The big ones back then were the shimming and peening. another was to heat and anneal the base of the rear sight and peen it then lapp to slide for a tight fit along with re adjusting the spring cover for proper tension.
One mod that was popular with new High power shooters was to have the rear sight slide bedded to the base ( easier than the peening and more accurate) then drill out the aperture hole and redrill to a .052 or .059 aperture size. done right this never showed and made a big difference in sighting. Better still was to install a NM sight with 1/2 Minute adjustments. I used bisonite to bed the sights and then lightly lapped to a smooth fit. the spring covers detante was re bent to provide proper tension. The reason for the bisonite was the hardened steel filler in it made it hold up much better.

[Multigunner]

I've read of a method used by some USN teams. They semi permanently bonded the hand guards to the barrel with Black RTV sealant.

[Outpost75]

I've read of a method used by some USN teams. They semi permanently bonded the hand guards to the barrel with Black RTV sealant.

We always used Marinetex.

[Bill*B]

I threw that little note of Hatcher's into the conversation to simply say - if you have a well used Garand, hold on to your hat when shooting for groups! - and give thanks if it holds an honest 4 MOA. But to answer the question, Master Sergeant Emmet B. McKinney's procedure is described in detail on pages 274 to 276 of "Hatcher's Book of the Garand". Attention to fit of the stock; where there is no clamping action, the wood should not bear on the metal; an even fit of the recoil shoulders; cut away any wood bearing on the operating rod. Select an operating rod that does not touch any part of the rifle during its movement. Assure that the lower band has a tight fit with no play. See that the rear loop of the gas cylinder does not bind. It should have a good snug fit at the front end. Adjust the trigger pull to 4.5 pounds with no creep. Whew! A lot of work. I love the old M1, she's as sturdy as a fence post, and covered with a most glorious history - but I can see why the AR is the current darling of those who want "little bug hole groups". The Garand (may God bless her) is a service rifle pure and simple, and those who enjoy shooting her should love her for what she is.

[Pirate69]

Good exchange of information in this thread. Makes me feel better about the 3"-4" cast boolit groups I am seeing.

[LynC2]

I also recall reading years ago that the early "gas trap" M1's were extremely accurate, often out shooting the star gauge 1903's. Unfortunately they didn't hold up in bayonet practice and were changed to the present form.

[15meter]

Do a Google search for Mann accuracy barrel. I have no confirmation, but I suspect this is what was used to test ammo.

[Outpost75]

Do a Google search for Mann accuracy barrel. I have no confirmation, but I suspect this is what was used to test ammo.

Yes, pictured in Hatcher's Notebook.

In the 1960s they used a Remington 722 or later 700 action with 1-1/4" cylindrical, straight barrel with stop collar in V-block.

Boots Obermeyer made lots of the 5.56 barrels for TW and LC.

[Multigunner]

The .30-06 ammunition still in use for .30 synchronized cowl mounted aerial guns had to pass far tighter primer ignition consistency tests than infantry Ball ammo.
Apparently once the .30 aerial guns were all but phased out millions of rounds of this ammo was released for ground use.
The M2 AP round benefited from more aerodynamic shape and tighter primer tolerances, resulting in a higher degree of accuracy at longer ranges.

[Larry Gibson]

Multigunner

Given your vast knowledge I have a question; over the years I have heard constant reference to early M2 AP having boat tailed bullets and thus were favored by snipers and NMC shooters for use in M1903s and M1s. Yet I have never found nor seen a single .30-6 AP bullet (US of course) that was boat tailed. All I've ever seen were the 165 gr FB'd AP bullets. I haven't even seen a picture or official reference to ant M1922 or M2 AP bullets being BT'd. Have you any reference to such boat tailed M2 AP bullets?

[Outpost75]

Multigunner

Given your vast knowledge I have a question; over the years I have heard constant reference to early M2 AP having boat tailed bullets and thus were favored by snipers and NMC shooters for use in M1903s and M1s. Yet I have never found nor seen a single .30-6 AP bullet (US of course) that was boat tailed. All I've ever seen were the 165 gr FB'd AP bullets. I haven't even seen a picture or official reference to ant M1922 or M2 AP bullets being BT'd. Have you any reference to such boat tailed M2 AP bullets?

If memory serves, the steel core in APM2 is boattailed, not for any aerodynamic reason, but to facilitate closure of the jacket at the base when the lead filler is inserted and the open jacket turned in. When fellows pick up shed AP cores on the ground from bullets which have broken up, they see the boattailed cores and it starts another barracks story about boattailed AP bullets.

I once saw a WW2-era study on Browning machinegun barrels lasting longer before they would fail a stripping test if used with AP ammo, and which gave better performance in the ground mount role than ball. In the ETO AP ammo was preferred, but cal. .30 aircraft MG loadings remained incendiary-tracer until most aircraft machineguns changed to cal. .50 by late 1943 and the combat linked-pack was changed to 5-M8API-1-M20APIT, which remains to this day.

None of this has anything to do with rifle accuracy, but pilot debriefs complained about the tight beaten zone if the cal. .30 guns when used with AP and tracer, and they preferred the looser nozzle on the fire hose afforded by firing the incendiary-tracer mix. But ground use placed a greater premium on both accuracy and penetration, and AP was preferred in the cal. .30 MGs once Ball M1 stocks were depleted.

None of it has anything to do with BT bullets, so I was told by Col. Thomas Cosgrove and LTC William C. Davis, Jr.

[Larry Gibson]

Outpost75

You're observations are the same as mine. Still some old NMC shooters insist they used M2 AP that had BT'd bullets?

[Outpost75]

Outpost75

You're observations are the same as mine. Still some old NMC shooters insist they used M2 AP that had BT'd bullets?

Mythology and folklore lubricated by the traditional debriefing shot of medicinal rye whisky...

[Larry Gibson]

You're probably right.......

[Multigunner]

The improved aerodynamic shape I spoke of was not due to any external boat tail shape. The steel core was given a boat tail because they found that when flat base hardened steel cores struck a steel plate at a slight angle the nose dug in and the bullet turned just enough towards the perpendicular that side force on the heavy base snapped the core in half. The lighter rear end of the boat tail core didn't cause this effect as often if at all.

The steel vs lead core allowed a much longer bullet for its weight, just as the .303 MkVII lightweight nose insert did. This improved long range performance. The effect is much like the rule of thumb that longer ships can reach higher speeds all else being equal.

The M2 AP bullets I've examined used a copper cup inserted in the base to act as a spacer for the boat tail. I suspect this was to prevent cores from being blown through if fired in a worn MG barrel.
At the time boat tail bullets were notorious for eroding the throats of extreme high RPM aircraft MG barrels due to blowby so a flat base was preferred. Blowby could overheat the jackets causing core blow through putting the gun out of action. Improvements in barrel metallurgy and bore hardening techniques made the cup and flat base unnecessary.
Steel cores don't upset so the copper cup performed that function to better seal bullet to bore.

There was a 1920 experimental Boat Tail AP .30-06. These are collectors items. Don't know if any were surplused but I doubt it.