M-1 Garand Loads

[slamfire1]

The part you have quoted was posted by MEHarvey, not me.

Right, sorry. If MEHarvey swings on by, I would love to know where he got the port pressures for the different powders.

Parashooter: I have the utmost respect for your postings.

As for powders and burn rate. The table below came from AMCP-706-260. The pamphlet was analyzing a M60 type gas system. I assume the powder is IMR 4895.



If you notice, the little table inset is the residue pressure. That is very important as all these gas operated mechanisms open up when there is residual pressure. The system is designed not to open up when at a pressure which will rupture the case. You can figure when unlocks happens by adding the times in the cycle table below.

Anyway, I have always believed, and correct me if I am wrong, that a slow burning powder would shift the pressure curve to the right. That is it would take longer to reach a peak pressure, and the pressure drop off would take longer.

If that were true, then having higher residual pressures at unlock would be hard on the mechanism, and the brass.

Here is a little table on time and cycle time for a M60 type mechanism.



And the pressure time curve for the M1 Carbine.



For me, I have had excellent luck with IMR 4895/AA2495 in the Garand, and when I open my keg of H4895, I expect to have excellent performance with it.

I also purchased a lot of WC852 powder and got the lot acceptance sheet with my powder. This powder was tested for use in the M1 Garand. My lot takes 60.1 grs of WC852 to push a GI 150 FMJ 2700 fps. Somehow they got the pressure curve right with that long powder column.

[cary m2a]

See its so simple when you can see whats going on in there

Thank you

Cary

[Parashooter]

"Anyway, I have always believed, and correct me if I am wrong, that a slow burning powder would shift the pressure curve to the right. That is it would take longer to reach a peak pressure, and the pressure drop off would take longer."

That would be correct when all other factors are equal. If we use a heavier bullet, however, its added inertia brings the peak back to the left, allowing the use of a slower powder. When we use a lighter bullet with less inertia, the curve moves right, allowing the use of faster powder to bring it back to the normal position. If we use a lighter charge, the entire pressure curve, including the portion at the gas port, moves down - as compared with a heavier charge and the same power/bullet.

As for residual pressure, your illustrations give an example of why that's not the problem some claim. Add up the times to unlocking (.003665, .000220, .001116) and we get about 5 ms. The pressure decay table shows zero pressure at just 4.3 ms. That gives a pretty wide margin for variation without having any significant residual pressure when unlocking is complete - at least with the mechanism for which the times are given. (I'd sure like to see a similar table for the M1.)

I have a quantity of similar "slow lot" WC852 and use it gladly in several bolt guns. While it's possible this is an exceptionally low mass/energy composition, I would choose another powder when loading for my M1 with 150-grain bullets. If it works for you, that's one more indication how all of us who don't have a ballistics laboratory handy are basically making guesses about what's really happening between trigger pull and muzzle blast.

[slamfire1]

Did you purchase your WC852 from GI Brass (Jeff Bartlett?). That is where I got my lot. It is Lot No. BAG 47287, tested in accordance with Mil-P-3984E 20 Nov 1972. A DoD Government offical witnessed the acceptance test, and signed that it met requirements.

WC852 was purchased and tested for use in M1 Garands. In my lot acceptance sheed they fired 100 rounds each in two M1’s to check for peening.

They don’t list a port pressure, but the “correct pressure” with a 152 FMJ was between 40,200 and 41,800 pounds.

This stuff if fine in Garands.

Jeff told me that there were several different 75,000 pound lots of WC 852 auctioned off. Accurate Arms got one, a faster one, and that became their AA2700 powder. I believe all their old stock is sold, so they stuff they are selling must be new manufacture.

It has given me excellent results with stuff in a bolt rifle with 168’s in the 30-06





And it has performed well with the 200 SMK in the few 1000 yard matches I shot.

It has given me excellent results in the 6.5 Swede, 7 mm Mauser, the 7.5 Swiss.

[Parashooter]

I don't know where my WC852 came from. A buddy dragged a heap back from Camp Perry many years ago. Based on my experience with it in .256 Newton, 6.5x55, 7x57, and 7.5x55, I'd guess it's a little slower than IMR4350. For example, in the .256 with 142-grain MK's, 50 grains of 4350 gave me 3005 fps (too hot!) and 52 grains of WC852 went 2848 fps with no sign of abnormal pressure.

If you like it in your M1, that's good. It's excellent powder and was dirt cheap when I got some. I just don't plan to use this batch in my M1.

[cary m2a]

I think WC852 is alot like AA3100 or H4831 SLOWWW stuff and AA2700 is junk had bad time with it in the .06 and .303 in bolt guns.

[MEHavey]

>
> So given the IMR 4350 port pressure is about the same, HOW
> are you getting the mass in there faster than IMR 4895?
>

>
> I would love to know where [the port pressures come from] for
> different powders
>

Second question first: The pressures come directly from QUICKLOAD, an internal ballistics program that I have found to be amazingly accurate as long as I do my part by insuring the combustion chamber/case volume are correctly entered by making sure I had case water volume (by weight) right on; as well as bullet seating depth/barrel length.

While Quickload actually gives simply reams of data, the pressure/velocity-vs-time & distance graphs below give you the idea. I ran a dozen powder combinations for 150gr/2,775fps through the system, from the slowest I could get until I ran out of case capacity to get the speed; and the fastest powder possible before I ran out of pressure at allowance at 56,000psi. (RL-19 on one end, and IMR4227 on the other. 4895 and 4064 falling right in the middle, naturally.)

I arbitrarily chose 1 second and/or 20 inches as the circumstances wherein the OpRod first sees pressure. Note that the OpRod moves under pressure over time no less than the bullet does -- that time being from the moment the bullet passes the port until the bullet exits the muzzle and pressure goes to zero. So it's an integration problem, not an instantaneous spike/slap.

Note the comparison (the pink/blue bars) the [U]huge[U] difference in energy transferred from gas to OpRod depending upon whether the powder burn rate is fast or slow.

As to Question #1: This is a fluid-flow problem, not that pressure spike we spoke about above. It's the application of pressure/force over both time and distance, and that pressure is actually the combined mass of each gas molecule banging up against the OpRod face. So mass come with the pressure by definition (or there isn't any pressure) and the mass flows through the inlet port like water. The higher the pressure, that more/faster that mass flows in as the piston moves away from its starting position over time, building up speed.

Someday I gotta work the equations out….

[heckinohio]

I am not as tech savvy as you guys, probably shouldnt comment at all. However, after years of successful casual target shooting with many Garands, I use IMR 4895 at 45.5 gr, military pull bullets at 150 gr (??). Reason for that charge is pure old guy cheapness as it works my 7.7 Jap. machine guns just fine. I can set a Lyman powder dispenser for that charge, load two different rounds without changing anything but the dies. Have done the same thing with other loadings. I have a bunch of powder dispensers but find that easier than constantly changing settings on them. Casual targets may not require the competition shooter demand, but golf balls at 30 yds are kinda a challenge........

About that op rod thingy, I made up an 8mm Garand as I was offered a new barrel for el cheapo and I have 3000 rounds of rusty WW 2 German MG steel case ammo. Powder and bullets are just fine. I duplicated the WW 2 German loading and promptly blew the op rod off. Investigation showed that the gas hole provided by the barrel mfgr. was .101, considerablly larger than the .080 (?) 30-06 hole. I used a repro solid gas plug, calculated the areas of the holes and drilled a .050 bleed off hole, wasnt quite big enuff as I got a couple of short strokes, so I opened it up to .052. Smooth operator now. PJHeck

[MEHavey]

`Glad the OpRod didn't wind up anyplace "serious."

:-)


.

[cary m2a]

I seen the same thing happen with a couple doses of 180gr BT with 57.5 gr of H4350 under it, and pop went the oprod Well it worked good for Elk.