Grouping?

[Wolf762x51]

For the life of me I cant tell if this is shitty shooting or if Im doing something wrong in the reloading process. The SDs ranged from 22 to 69 (f$#/!) with the center group being omitted due to it being too dark for the crony to function. Center group was the best and the only one that had uniformed flash holes. (They had been done first and sat for weeks because of the weather and I only recently got the flash hole deburring tool)

 

[Darkside-Six]

Regardless of how it is grouping, if your SD is that high then you need to find another load. Your SD should not be above 10.

 

[GhengisAhn175]

What's your CBTO or jump set at?

Youre range of charges is too low.

For proper load development start at a 20 thousandth jump and go up in .3-.5 increments.

Look for stable #'s across 2-3 loads and pick the middle the. Work seat depth (seating deeper only ) until you find a 1/2 MOA group WITH stable #'s

 

[MtnCreek]

"The SDs ranged from 22 to 69 (f$#/!) with the center group being omitted due to it being too dark for the crony to function."

I'd disregard all the velocities. If you couldn't get readings on the last group due to lighting, the rest are probably wrong.

If you're shooting a cartridge that has factory match ammo available, shoot a couple boxes of that for a base line. If it shoots the same, that may be the limit of your or your rifles accuracy. If that's the case, pick a load and practice shooting instead of focusing on load development.

 

[Wolf762x51]

I dont have a veocity baseline, but the rifle performs well with Fed GMM

 

[mrjinglesusa]

It would help to know what you're loading - 308, 6.5 creedmoor, 260, etc. and what you're shooting it out of. Also, what bullet and powder?

For example, if you're loading 6.5 Creedmoor and using H4350, that 41.8 is at a well-known node in the 41.8-42.1 range for H4350 pushing 140-147 gr bullets.

 

[Wolf762x51]

It would help to know what you're loading - 308, 6.5 creedmoor, 260, etc. and what you're shooting it out of. Also, what bullet and powder?

For example, if you're loading 6.5 Creedmoor and using H4350, that 41.8 is at a well-known node in the 41.8-42.1 range for H4350 pushing 140-147 gr bullets.

My mistake, the loading is as follows:
-Fed GMM brass (once fired from the same rifle)
-IMR4064 - varying charges, i found that the fed brass is much thicker than most cases, im crushing powder at 42gr instead of the published 44 max.
-CCI large rifle primers
-Sierra 175gr TMKs

 

[jmtyndall]

41.8 would be expected to replicate Federal GMM 175.

Lighting may have impacted your chrono readings and your sholting. I'd try again and work up 41.2 41.5 41.8 42.1 42.4

Try settling the powder with a drop tube or vibrating toothbrush to avoid excessive crunch

 

[mrjinglesusa]

My mistake, the loading is as follows:
-Fed GMM brass (once fired from the same rifle)
-IMR4064 - varying charges, i found that the fed brass is much thicker than most cases, im crushing powder at 42gr instead of the published 44 max.
-CCI large rifle primers
-Sierra 175gr TMKs

Just so happens that 41.8 IMR4064 pushing a 175 gr bullet is also a well-known node in .308. I'd focus on that area and maybe load up some 41.7, 41.8, and 41.9. You'll find your best load at one of those weights I bet. That 41.8 might even be it. I like to shoot at least 10 rounds minimum when getting velocity data - I bet if you shot 10 rounds of the 41.8 in good lighting you'll get a nice low SD.

 

[jwood1284]

I'm seeing a lot of chatter about having a hard time getting 175TMKs to shoot. I'd try the same workup with 175SMKs and see what happens.

 

[jmtyndall]

The new TMK has a different ogive shape that makes it less forgiving in regards to jump. The 175 SMK is the standard for a reason.

Although the 155 gr 2156s are pretty darn good too