Help me shrink my group size....

Koda

Koda

Hammer Time Executive member
Ive enjoyed learning to handload hammers and have produced usable results but I would like to shrink my group size. Last year I developed hunting loads for my 280ai and my 6.5 Grendel to use on elk and deer, respectively. Both of these loads are getting me around 1.5moa, which to me, is usable at the distances I hunt with (though I would like to increase my range) which currently is out to 300yds. I can repeatably hit 400yds with my 280ai but not comfortable yet judging wind to hunt that far out but learning.

Some caveats; likely someone might recommend a different component which is fine, but I'm not likely to switch right now due to supply chain availability plus the cost of powder and primers. Feel free to mention it, but really I would like to learn if there is something I can do with what I have.
Also, feel free to ask about my shooting technique and rifles, it might not be my handload recipe.

But I believe both rifles and my shooting skill are more capable than 1.5moa as I have held 1moa groups before, I can discuss as needed in the discussion. Open to any advice and critique. Is there anything I can do to achieve at least 1moa?

I will start with the recipes:
280ai, Peterson brass annealed, CCI BR2, 58.1gn H4350, 1/8t crimp (FCD), 140gnAH, 2.520 coal, .079" jump, 3200fps, Browning Xbolt, 26in bbl, 8 twist zeroed at 100yds with a CDS dial for drops.
6.5Grendel: Starline Brass annealed, CCI 400, 32.2gn A2520, 1/8t crimp (FCD), 97gnAH, 2.250" coal, .075" jump, 2813fps, Satern barrel, 20in, 8 twist AR15. The Grendel is intentionally zeroed 1.5" high for a 200yd zero.

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Forgive the grainy photo taken thru my computer screen so I could use the ballistic x app, original target photos taken last summer. The 280ai label has a typo in the bullet weight, should be 140gnAH.
 
LightTheTower said:
That’s an option. I’d go 1/4, 3/8, 1/2… unless you’re current 1/8 load is border line high pressure.
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Id have to look at my notes from last summer, I think Im at least .5 to 1gn below first sign of pressure. Im not familiar with how much crimp influences pressure so Id have to approach this with caution...
 
Koda,
What load development steps did you take to reach these loads? For example, for the 280ai what charge testing did you do and why did you settle on 58.1g? What jump testing did you do and why did you settle on 0.079”? You’ve answered re. your chosen crimp.
 
OutdoorEdventure said:
I’d be more interested in hearing the rest of the shooting system and how well the cartridges shoot with non-Hammer Bullets as a medium.
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Both rifles are new last year, and have never shot anything but these hammers.
The 280ai I started out with Nosler brass and that recipe did get me under 1moa groups. Ive thought about going back to Nosler brass over this.
 
BigGame said:
Koda,
What load development steps did you take to reach these loads? For example, for the 280ai what charge testing did you do and why did you settle on 58.1g? What jump testing did you do and why did you settle on 0.079”? You’ve answered re. your chosen crimp.
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For both my process was start with a pressure ladder and find the first hint of pressure. Back off at least .5gn charge weight and zero. This is all I know to do based on tips from the reading here.
Seating dept was based on keeping the bullet closest to the lands and placing the crimp into a pdr valley. Crimp was selected at random since Ive never crimped before I just started at "1/8 crimp".
Note: on the Grendel I have to crimp to keep the gas operation from moving the bullet during cycling. I dont need to crimp the 280 but just did it when I switched to the Peterson brass cause I read its better to start with a light crimp if you need to adjust later on. Im tempted to load 5rds with no crimp and see how they do.
 
Koda said:
Id have to look at my notes from last summer, I think Im at least .5 to 1gn below first sign of pressure. Im not familiar with how much crimp influences pressure so Id have to approach this with caution...
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My 280 REM load is 58.5 gn of Acc 4350 with 131 HHH and 1/2 crimp. It is definitely at pressure, but 1/4 to 1/2 crimp didn’t increase pressure much if any, and improved accuracy by at least a quarter moa.
 
LightTheTower said:
My 280 REM load is 58.5 gn of Acc 4350 with 131 HHH and 1/2 crimp. It is definitely at pressure, but 1/4 to 1/2 crimp didn’t increase pressure much if any, and improved accuracy by at least a quarter moa.
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Its helpful to get a feel for how crimp affects pressure, thank you. I could try 3rds each on a crimp ladder, if needed can pull the bullets if I hit pressure early. I could consider backing off half a grain of charge weight if more crimp puts me over pressure but Id like to keep the 3200mv Im at if possible.
 
Koda said:
For both my process was start with a pressure ladder and find the first hint of pressure. Back off at least .5gn charge weight and zero. This is all I know to do based on tips from the reading here.
Seating dept was based on keeping the bullet closest to the lands and placing the crimp into a pdr valley. Crimp was selected at random since Ive never crimped before I just started at "1/8 crimp".
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There are lots of load development methods that work well. If a dozen of us were to list our own, you'd have a dozen different ones to choose from. But I'll list the basic elements of mine because to my eye you have not yet conducted a charge test, a seating depth test, or a crimp test (if you want to crimp). At the broadest level, I consider the ignition side of things (charge, primer) to control gross group size and seating depth/neck tension to refine group size. Crimp fits into this latter category, but is hard to refine delicately, in my experience. Caveat, I like to test and don't mind expending components to do it, so my method may not suit many.

1) Measure distance to lands and pick a starting jump distance (pick your favorite).
2) If necessary, run a quick pressure test to find max pressure. This is for safety and it sounds like you've done it, but it's not a charge test.
3) Run a charge test. Pick a range of charges beneath max pressure and load/shoot a group at each while recording velocity over a chronograph. The number of shots in a group and number of charges you try is a function of your own testing principles. In analyzing the results, I'm looking more at the average velocity and SD of velocity for each group, rather than the group size. I want to find an area over ~3 charges where the velocity is more consistent both in terms of velocity increase and SD. Pick a charge in the middle of that zone (often called the velocity node).
4) Run a seating depth test using that charge. Same idea - take a range of seating depths and load/shoot a group at each. Here you are looking at group size, though you'd still like to see a trend where 2-3 depths are similarly small with larger groups on either side. Choose the depth in this zone with the shortest jump/longest OAL (this is so as your throat erodes you're staying in your seating depth node).
5) You're either done, or you commence going back and doing a more refined charge test with smaller increments using your chosen seating depth.

Crimp is an additional element that can also be tested/tuned just like charge and seating depth. For me, if it's a load where I know I want to crimp, I run all of these tests with the same light crimp (maybe 1/8) and then at the end possibly tune crimp if I feel it's needed. If it's a load where I may not use a crimp, I do everything without a crimp and then experiment with it once I'm happy with the load.

I lot of folks will disagree with my method (including you) and that's ok. The main point I wanted to suggest is that reloading and finding accuracy is all about tuning charge and seating depth at a minimum. You can also tune crimp, neck tension, case prep methods, different components, etc. It's endless, which is the fun of it.
 
I would play with fore end pressure. Assuming action and barrel channel are bedded properly.

Lay down strips of electrical tape increasing until "sweet spot" is found. For further experiment add until groups open up again.
 
BigGame said:
But I'll list the basic elements of mine because to my eye you have not yet conducted a charge test, a seating depth test, or a crimp test (if you want to crimp). At the broadest level, I consider the ignition side of things (charge, primer) to control gross group size and seating depth/neck tension to refine group size.
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This is very well written and something I will dig into. I feel like I got lucky with the Nosler brass group size though I was hoping for more velocity, but I let the rifle harmonics choose that load. When I switched to Peterson brass I simply started over except I attempted to stay with the most velocity. It sounds like your development is a hybrid or influenced with the traditional OCW test, and Ive wondered if refining charge weight around my current load might tune in group size faster. I dont know, my question now is if Im getting 1.5moa would that be considered a controlled "gross" group size?

I might start with a simple crimp ladder as suggested above, to see if I get lucky. But also test some charge weights or seating depths around my current. I could do this all in one range day to save time and make it a day at the range.
I really appreciate your tips here.
 
Koda said:
my question now is if Im getting 1.5moa would that be considered a controlled "gross" group size?
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1.5 MOA certainly is not bad. But whether or not it's optimal for your gun and load can only be answered through testing.
 
HARPERC said:
I would play with fore end pressure. Assuming action and barrel channel are bedded properly.

Lay down strips of electrical tape increasing until "sweet spot" is found. For further experiment add until groups open up again.
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I would rather tune the handload to the rifle, personally.... but, the rifle is floated and bedded from the factory and whats really odd is the instruction manual says in bold letters not to take the firearm apart. I'm kinda perplexed what to do with that since in Oregon I do hunt in the rain, a lot. Ive always taken stocks off after the season and let the rifles dry out inside.
At least it's a synthetic stock.
 
bodeen said:
If possible, maybe let someone else shoot the rifle and see what happens.
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Would it be beneficial to ask a random stranger at my range? I have only 3 friends that hunt, let alone shoot rifle. Im sort of on my own, with anything handloading and shooting.
 
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