Huge spread with IMR 4895 in Garand

[griff383]

I just got back from the range and had some undesireable results with IMR 4895 and my Garand.

I loaded 45 and 46 grains of IMR 4895 under 175gr SMK and had a very large spread. This is the data I got:

45 grains
Hi Vel: 2569
Low Vel: 2393
Ave Vel: 2463
Ext Spread: 176
Std Dev: 68

46 grains
Hi Vel: 2583
Low Vel: 2464
Ave Vel: 2507
Ext Spread: 119
Std Dev: 47

All loads were individually hand weighed with the same brass and CCI #34 primers. Weather was perfect, low humidity and 70 with a few clouds. Is this typical or did I get a bad lot of powder?

 

[243winxb]

Don't have a Grand, Maybe throw 47gr in for a try. What brass?

 

[MEHavey]

Because of relatively low case-fill ratios, 4895 loaded to Garand specs has a lot of room to move around in that 30-06 case. (≤ 80% case fill for your loads)

I find that if I tip the rifle vertical before firing (setting the powder against the primer, I'll get a 100fps increase over rolling the case horizontally to distribute the powder evenly and gently closing the bolt on it. Normally the Garand leaves the powder somewhat toward the far end of the case as the cartridge smacks up against the chamber shoulder and comes to a halt. If the rifle is then handled in such a way which redistributes the powder backwards.... Well there goes the 100fps rubber tree plant again.

 

[USSR]

griff383,

With such a low charge weight in a case with a fairly high case capacity, you will get high ES and SD numbers. Remember, LC M72 Match ammo with it's 174gr bullet is rated at 2640fps at 78'. Since we normally take chrony measurements at about 12', you can figure that M72 is generating about 2680fps at 12'. I normally use 46.5gr with the M72 bullets in my Garands, so try 46.5gr to 47.0gr, and see if both your ES and SD numbers don't improve with the increased velocity.

Don

 

[rg1]

My loads with IMR 4895 shooting 150 gr. pulled fmj-fb bullets. At 45-46 grains I was getting low velocity and bigger than normal spreads. At 47 grains it stopped and velocity was normal and spreads were low. I believe the above posts about powder position in the case and low case fill does have an effect. I thought it was unusual for just a half to one grain increase to make such a difference but it did. I shoot 150 fmj-fb surplus and Hornady 150 SST's and Hornady 150 fmj at 47.5 grains in LC, RP, Win cases with RP 9 1/2 primers. Accuracy is good and velocity is in the normal range. I've read that IMR 4064 performs better with the heavier bullets in the Garand?

 

[griff383]

Don, thanks for the info. Ill get some loaded up at 46.5 and 47 and see if those numbers dont change for the better. May I ask what is "normal" for your ES DS numbers?

I also have IMR 4064 and could try that with the heavier bullet

 

[MEHavey]

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