M1 Garand blow up

[CINDERS]

That's what I do Patrick I may have allot of powder out but there is only one powder on the bench at any one time the rest are on the floor and are locked back up when I have finished loading for the day, when I am changing powders I clear the bench of the just used powder container put it on the floor and grab the next one and up on the bench it goes for the rifle it is used in I do not even leave empty containers of the same powder on the bench if that happens straight in the bin with the empty grab a freshy. And another thing I do not do is drink alcohol when reloading a sure recipe for disaster......

[Bill Hollinger]

Great point fellas.

Because shotgun powder is near impossible to get I had three different powder brands to reload three cases of shells. I would make sure I didn't load odd numbers (all in 25 round increments) so I had no loose rounds. I would empty the machine (Pacific 366) of all hulls and rounds prior to moving on to the next brand of powder. Each brand takes it's own specific powder bushing to get the desired fps charge of grains. I then marked each 25 round box with the powder brand and grains so there was never any confusion.

No alcohol is a must also and thank you for bringing that up Cinders.

[DocAV]

Two factors here: Steel case and Unlocking speed.

Steel cases in Rifles designed for Brass ( as was the original .30/06 Garand) don't go very well ( I found this with French Grey steel cases (.30cal) and extraction problems.

But the major cause of this .308 ( for want of a better term) problem is in the Conversion from Normal "Garand" to Short Barrelled "Tanker" (Misnomer) in .308.

The Garand works at a certain Port Pressure ( not to exceed 15,000 PSI); the Longer Garand Barrel and the Progressive 4895 type powder of the 30/06 gives this Optimum operating Port Pressure. The delay in opening and extraction time allows the Brass case to retract from the Chamber walls, and be extracted.

With a conversion to shorter barrel, probably with the Same Gas Port diameter, the Port Pressure is much higher ( given the same or higher chamber pressure of the .308 cartridge)
and so the Case (Brass or steel) is being "extracted" whilst the cases is still "stuck" to the case walls. Hence the Partial Head separation and eventual Destructive Gas escape, splitting the stock. Effectively, the Increased velocity of opening, allowed the Bolt's extractor to over-ride the rim, and lose Bolt head support of the case whilst the Case was still stuck to the chamber walls. With steel cases, this is very Problematical.

Your Flattened Primers are not a sign of "Bad Loads" but of Incorrect (too high) residual pressures due to Short Barrel and early Opening of the action.

The Problem is how the rifle was converted, and using "Non-complying" ammo case material.

If you read all the Books on the Development of both a Full Auto .30 cal Garand, and subsequent development of the M14 rifle, you will see that balancing Gas pressure curves and Bolt opening velocities is not an easy Matter. SA/FA rifles which have "gas regulators" or "Gas expansion cutoff systems" will always work better with Both Brass and steel ammo, if properly adjusted. Those which don't have these Gas variability mechanisms, will fail (Case or Mechanism) if the "Wrong" ammo is used (or a Barrel length is changed, without changing the Gas Port diameter).

any further discussion as to the technicalities of this problem can be done directly, at
info@avballistics.com.au ( personal experience with both .30/06 and .308 shorty Garands, and other "shorties" as well (SKS, FN-FAL, etc) where position of Gas Port is changed, or calibre is changed ( ie, a .308 x 1,6" in a SKS).

Another example is Swedish Ag42B, if the Gas port gets burnt out, the action will tear case rims off Brass cases ( ie, opening cycle too fast for Brass retraction).

Doc AV

Maybe the Cabellas Herter ammo was not at fault after all, except for being Steel, rather than Brass.

[Skip]

Sunday a fellow shooter just purchased an M1 chambered in 7.62X51. He never owned or shot a Garand. While he was sighting in I noticed on certain shots there was a muzzle flash. I looked at his loaded clips and he had a selection of LC09 and steel zinc coated Colt ammo. When I see him again I will provide the Youtube video for his consideration.

[browningautorifle]

steel zinc coated Colt ammo

I've never seen that stuff. We get zinc cases MFS ammo up here though. I don't bother with it.

[Skip]

20 rounds Colt .308 Win 168 Grain FMJBT Zinc Plated Ammo - 421120, .308 Winchester Ammo at Sportsman's Guide

[browningautorifle]

Seen Skip, thanx...

[CINDERS]

Are they steel cased hence being zinc coated just asking.

[browningautorifle]

The ones I have around here are not steel, just the softer stuff. The don't rust.

[Skip]

Are they steel cased hence being zinc coated just asking.

Steel case and Berdan primed.