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Anyone got a minute to load some numbers into quickload? I'll be your best friend.







#1
I reload for Grendel, but I'm not able to get my usual bullets or primers, so I'll be grateful to anyone who can run some numbers on what I was able to get. I'm happy to share results after the next range visit.

So 6.5 Grendel:
Case capacity is 35g h2o
Cci400 primers
Hodgdon cfe223
130gr Sierra TMK. (1.38" length boat tail)
COAL 2.275"

My barrel is a 22" 1:8 twist 5R

Thank you in advance to anyone who can help me out here.
 

rw blakemore

Member
Forum Supporter
2019 Supporter
#2
Assuming your H2O case volume is for a fired case I would use one of the following (ambient temp of 70F). If you choose to try these, remember they are estimates. Proceed with caution and always check the case for signs of over pressure.

26.7 gns Mv~2355 fps
27.4 gns Mv~2420 fps
27.9 gns Mv~2465 fps

Recommend you start with the 26.7 gn charge. You may have to increase or decrease the charge slightly to produce a muzzle velocity of 2355 fps When you have a charge at or near 26.7 gns that produces a muzzle velocity of 2355 fps , try the 27.4 gn and 27.9 gn charges to determine which one produces the best precision.
 
#3
Assuming your H2O case volume is for a fired case I would use one of the following (ambient temp of 70F). If you choose to try these, remember they are estimates. Proceed with caution and always check the case for signs of over pressure.

26.7 gns Mv~2355 fps
27.4 gns Mv~2420 fps
27.9 gns Mv~2465 fps

Recommend you start with the 26.7 gn charge. You may have to increase or decrease the charge slightly to produce a muzzle velocity of 2355 fps When you have a charge at or near 26.7 gns that produces a muzzle velocity of 2355 fps , try the 27.4 gn and 27.9 gn charges to determine which one produces the best precision.
Thank you sir! I'll keep fingers crossed and post results sometime this weekend.
 
#4
I suspect my powder scale may be reading a bit high, but here we go...
With 5 shot groups
26.7 averaged 2160fps e.s. 41fps
27.4 averaged 2248fps e.s. 23fps (best group @ .75 moa)
27.9 averaged 2318fps e.s. 21fps

Primers look fine throughout. I appreciate the help. Gonna have to double check calibration on my scale, but I'm on the right track. Grendel does like the TMK's.
 

rw blakemore

Member
Forum Supporter
2019 Supporter
#5
I hope you find that your scale reads high. I ran QL again to determine what the powder charge would have to have been to produce such low muzzle
velocities. Looks like your scale reads approximately 1.6 to 2.2 grains high.

1616469917301.png
 
#6
I weighed a 130gr bullet as a test and got 129.9, so it seems to be pretty spot on.
There's some sort of unaccounted for variance, but no biggy.
I'll go a wee bit higher, like .3gr at a time, and just keep a close eye on primers and any unusual extractor marks on the rims.
 

rw blakemore

Member
Forum Supporter
2019 Supporter
#7
The variation is significant and may be attributable to the case volume we worked with. Both SAAMI and CIP case volumes are listed as 37.5 gns H2O. We used 35.0 gns H2O for our QL estimate. In my experience the "fired" case volume is always greater than the SAAMI spec volume. If your "fired" case volume is nearer 38.5 gns H2O, for example, the velocity estimated by QL drops to 2260 fps for the 27.4 gn charge. That is within 1% of the observed velocity (2248 fps) for that charge. If you find your "fired" case volume is actually larger than 35.0 gns H2O, let me know the new number and I'll run QL again if you think it would be helpful. If not, it's been a pleasure. Take care.
 
#8
I think you’re on to something. You may be right. I was going off the Wikipedia entry and what I measured via water displacement test, but that can be off due to cohesion. I’m good though. You’ve been a big help and I think I can take it from here. Much appreciation for getting me on the right track.