Author Topic: Seeking advice on CMP for an M1 Garand  (Read 599 times)

C.N. Double

  • Newbie
  • *
  • Posts: 23
Re: Seeking advice on CMP for an M1 Garand
« Reply #15 on: February 26, 2019, 01:58:10 PM »
I replaced the clip latch spring and the op rod spring -- not sure if those were a problem, but they were cheap, and I wanted to rule them out. When I got this rifle apart, it was very clean and well greased. I only had to add a bit of grease to the bulge in barrel where the op rod rides. When I try it later this week, I'll also see which clips are causing problems.

I'm up and running with the IMR4895 load, but it doesn't meter very well in my RCBS Uniflow. I'm going to try H4895 since has a very similar burn rate and supposedly meters better. I'm trying to extrapolate the load data for both IMR and H4895, but it almost looks like I could use these two powders interchangeably for this load. I think I'll start with 35.0gn of H4895 and adjust until I get ~1850fps.
C.N. Double
(formerly Lobo Too Slow)

Garrison Joe

  • Hero Member
  • *****
  • Posts: 861
Re: Seeking advice on CMP for an M1 Garand
« Reply #16 on: February 26, 2019, 02:06:07 PM »
IMR 4895 and H4895 do not load to exact same weight.  But for cast bullet use, weights for same velocity will be fairly close, and certainly safe to interchange.

I get better results with a slightly faster powder, like Reloder 7, in 30 cal cast bullet loads.

Most folks can't get target accuracy throwing powder with measures.   That's what tricklers are for.   I use a measure, then dribble a few grains while on a good scale.

Good luck, GJ
"Ride hard, shoot straight and speak the truth."   Col. J Cooper
Why else would you want to be here?

60708 Life/Regulator

C.N. Double

  • Newbie
  • *
  • Posts: 23
Re: Seeking advice on CMP for an M1 Garand
« Reply #17 on: February 28, 2019, 12:59:05 PM »
I tested my loads today, and the results were interesting. IMR4895, despite throwing +/- 0.4gn on each charge, was the most consistent in both velocity and accuracy. H4895 did OK, but I had a couple of malfunctions with the lighter loads. Overall, I think I'll keep loading the "tried and true" load with IMR4895 and not worry about the powder measure throwing imperfect charges. If I start shooting longer distances or more competitively, I'll have to tighten up these numbers.

I only had one 6th round stoppage (in 9 clips), so I just gave that clip to a guy at the range who got excited every time he heard the *ping*. Win/win.

Here is all the data I collected today. All loads used Winchester LR primers, .310 Hi-tek GCSil 170gn bullets from Norm Purcella, and mixed brass. 16 shots each.

H4895
charge: 33.0gn (+/- 0.2gn)
Avg velocity = 1899fps
Std Deviation = 31fps
High/low velocities = 1963/1839

H4895
charge = 34.0gn (+/- 0.2gn)
Avg velocity = 1960fps
Std Deviation = 52fps (yikes)
High/low velocities = 2048/1823

** I didn't shoot the ones loaded with 35.0gn of H4895 since velocities were already higher than I expected.

IMR4895
charge = 35.8gn (+/- 0.4gn)
Avg velocity = 1963fps
Std Deviation = 31 fps
High/low velocities = 2011/1899

Thanks again for all the help.
« Last Edit: February 28, 2019, 01:30:51 PM by C.N. Double »
C.N. Double
(formerly Lobo Too Slow)

Goatneck

  • Moderator
  • Sr. Member
  • *****
  • Posts: 299
    • WBAS Committee & Ambassadors
Re: Seeking advice on CMP for an M1 Garand
« Reply #18 on: February 28, 2019, 09:43:02 PM »
CND

Keep in mind the higher elevation ( above sea level) velocity will change and point of impact will change also.  Where Dusty and I live elevation is about 650 above sea level.