Help with OCW target analysis

A

ACRVIPER

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Full Member
Minuteman
Jul 5, 2014
8
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Kansas City
#1
image.jpgGun: Remington 700 AAC
Chassis: McRees Precision
Optics: Vortex 6x24 Viper PST
Barrel: stock 20" with JP brake
Temperature: 84
wind: 12 mph headwind from NE
Yardage: 100
Brass: Lapua, case fired
Primer : Wincheter
Bullet:178 gr A-Max
COAL: 2.871
OGIVE: 3.245-3.249
Powder: Varget

OCW from 41.9-45.3 grain Varget

Very disappointed with (lack of) grouping.

What do I do now?
 
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#3
with Lapua brass, Varget, and 178s you should see a node right around 44gr. Load a few a couple of increments down and a couple of increments up from 44gr about 0.010 off the lands and see what you get. Remember, you're not looking so much for a tight group as consistent POI between a string of charges. I suggest 43.6, 43.8, 44.0, 44.2, 44.4. Remember to include an extra as a sighter/fouler and to take your time.
 
#4
graduations are too far apart, and charges at the top end are way too hot (just because fresh brass doesn't initially show pressure signs, that doesn't mean you're okay there)...

your accuracy node would be at 42.6 grains, and there ought to be anohter at 43.8 grains

Did you only shoot one shot at the lower charges?

Shoot a group at 42.6 grains, and it should look good. And if you really have to push it, see what 43.7 to 43.9 looks like (but that'll be on the warm side, I would think).

Dan
 
#7
Thanks for the help thus far. I measured the COAL to the lands at 2.960 and the ogive at 3.335 (Hornady comparator) from my R700 AAC and I loaded them to 2.871 COAL and targeted the ogive at 3.247.

I only loaded and fired 1 at the lower ranges and bumped up by 1% for the last 4 loads.

I'll give a whirl at 42.6-43.6-44.4 ranges at .7 increments (and take a look At the excel file)



Worst case, I can always move back to my 168 SMK's which shoot very well from this gun.
 
#8
ACRVIPER said:
Thanks for the help thus far. I measured the COAL to the lands at 2.960 and the ogive at 3.335 (Hornady comparator) from my R700 AAC and I loaded them to 2.871 COAL and targeted the ogive at 3.247.

I only loaded and fired 1 at the lower ranges and bumped up by 1% for the last 4 loads.

I'll give a whirl at 42.6-43.6-44.4 ranges at .7 increments (and take a look At the excel file)



Worst case, I can always move back to my 168 SMK's which shoot very well from this gun.
Click to expand...

That .089" jump may not help things with the Amax, but I'm sure you don't want to be single-feeding, either. Let us know how your tighter-graduated ladder turns out.
 
#9
I think I can clear the mag with a 2.900 COAL, but that is still off the lands by .060. Darned ol Remington's with the long throat! I thought I would find the sweet spot and play a little more with the COAL to see if it tightens the groups. I have another load group ready to go to the range from 40-44.2, with 1 at 40, 40.8, 41.6 and 3 at 42.4, 42.7, 43,43.3, 43.6, 43.9, and 44.2.
 
#11
I set my range from 42-45 so my spotters were only x1. I am repeating from 40-44.2. My new set is 1 at 40, 40.8, 41.6 and 3 at 42.4, 42.7, 43,43.3, 43.6, 43.9, and 44.2. Hopefully the wind will die down tonight.
 
#12
oldfatguy said:
Loading 1 @ at the three lower charges that are .8 apart ? Why?

OFG
Click to expand...
The published OCW methodology calls for that approach.

I could be wrong, but (A) some spotters/foulers are needed to start (and after mid-way cleaning), and (B) hard to publish a methodology that does other than recommend "choose a published max and start 10% below it to work up" . . . but then you need to skip safely/quickly past the lowest charges you'd rather not use anyhow. Hence the bigger steps.

Personally I just make more of the lowest charge actually being tested. So in Viper's case I might make 6-9 more of 42.4gr (or some at 43.9) rather than 3 x 40.0, 40.8, 41.6 depending on how I decided to conduct my version of that OCW test.
 
#13
Right you are. Just re-read the instructions and will plead CRS.

The 2% steps serve both as sightseers and to check pressure, very efficient, but not getting to the max loads.

Being somewhat OCD I use the 0.010" jammed program in the sticky at the top to establish pressure limits up to two .3 grn steps (.6 grn total) above the biggest load I'll use for the OCW work up. Those will be backed off to jump 0.025". Belt and suspenders.

OFG
 
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#14
Well, I just got back from the range and the results were a little more promising. I still need to adjust my POI, but will do when I get a load dialed in.

My new set is 1 at 40, 40.8, 41.6 and 3 at 42.4, 42.7, 43,43.3, 43.6, 43.9, and 44.2.

So do I focus on the 43.3-43.6?
 

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#18
ACRVIPER said:
Well, I just got back from the range and the results were a little more promising. I still need to adjust my POI, but will do when I get a load dialed in.

My new set is 1 at 40, 40.8, 41.6 and 3 at 42.4, 42.7, 43,43.3, 43.6, 43.9, and 44.2.

So do I focus on the 43.3-43.6?
Click to expand...

Looks like Dan was right. 43.8gr is right about where I would tune things. Your POIs between 43.6 and 43.9 are about the same.
 
#23
ACRVIPER said:
Gonna look at 42.4-42.7 and 43.6-43.9. Then hopefully I can pick a clear winner. Thanks everyone.
Click to expand...


I've been playing around with quickload with the same components. Given your barrel length and seating depth, you should be on an optimal barrel time node at ~42.6g. Does it chrono at ~2475fps? Mostly trying to figure out of this darn program works.
 
#25
43.3 to 43.9 are starting to look good. Please remember that you are shooting a factory Remington and there is nothing that you can do to improve accuracy more then replacing the barrel no matter what ammunition you feed it. Shoot a 10 shot group with 43.6 and be happy with 1.5 MOA and call it a day provided your ES is 50 FPS or less for out to 600 yds and 25 FPS or less if you want to shoot 800. You can also buy and shoot a box of Federal GM match ammunition and it will provide you a good baseline or shoot a 168g with 41g H4895. I also suspect you will get slightly better results with a 168 or 175 BTHP bullet, the AMAX bullets are kind of long and pointy for a factory rifle.
 
#26
Did I read in your first post that you are shooting at 100 yards? If so, you might try backing up another hundred or two and see if the results become easier to interpret.

The loooooooonnnngg throats in my Remingtons always seem to prefer Sierra bullets.
 
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