Reading groups OCW - input requested

[Checkmate101]

I’ve been doing quite a bit of reading about group reading and OCW reloading. Tried taking a stab at this to understand it better from a practical perspective. Looking for input to see if I am understanding this correctly.

Rifle/load:
ARC CDG, PVA 26” barrel, 7 twist
Barnes Match burner 112gr seated .020 off touch
6GT alpha virgin brass
N150
CCI 450

I realize the barrel needs to break in, however, this is more to further the learning process for myself and get a better handle on the reloading process/reading targets. All groups are 3 shots. Data is presented, only because it was collected. I’m not putting much stock in numbers from 3 shot groups. Was more looking for speeds produced is all.

I think there is a potential space to test further at 32.0-32.6 and maybe a bit outside those ranges. The 32.9 group I think may be the start of the scatter node. Maybe also something starting at 33.5, but I’m not intending to run it that hard unless I can’t find anything lower to work with. Planning to run 2800-2850. Let me know your thoughts. And as always, thanks for the help in advance.

 

[SVT_Tactical]

Any pressure signs at 33.5? Certainly stands out as the better 3 shot group. Maybe start at 33.2 and do a ladder test at 33.2, 33.5, and 33.8 if no pressure was there at 33.5.

Not super familiar with the 6gt but I'm thinking of should run a tad faster than 2850-2900

 

[Clancy]

32.3, work on your depth in .003 steps.

Check back after 200 rounds.

That’s exactly how it’s supposed to work. Well done.

 

[Checkmate101]

Any pressure signs at 33.5? Certainly stands out as the better 3 shot group. Maybe start at 33.2 and do a ladder test at 33.2, 33.5, and 33.8 if no pressure was there at 33.5.

Not super familiar with the 6gt but I'm thinking of should run a tad faster than 2850-2900

No pressure signs at all. With hornady brass I got pressure around 34.8 of n150. It can definitely run faster, I have just enjoyed shooting it at a lower velocity for PRS. Seems easier to spot impacts/misses.

I also plan to do some more F-class matches with this.

 

[jelenko]

32.3, work on your depth in .003 steps.

Check back after 200 rounds.

That’s exactly how it’s supposed to work. Well done.

But, 32.0 is left of the POI. 32.3-32.9 looked like they had POI's closer

 

[RegionRat]

Sorry, my vote is it is either the loading, wind, or just all within the dispersion.

There is too much back and forth between AZ and EL between steps.

That would mean no load stability, or, it is all within the dispersion, or there was a problem with the test. I would keep working on it but either the gun, the load, (or both) is/are not ready to show us any sweet spots.

I wouldn't despair, if we aggregate all those shots and consider the charge range, it means the rig will be okay, just probably not in the 2s or 3s yet.

BTW, When you only have three shots, you don't need to bother with calculating SD, the AVG and ES is enough.

Make sure you are either shooting round robin, or watching wind flags, preferably both. Good Luck and in for the range reports.

 

[jelenko]

Any pressure signs at 33.5? Certainly stands out as the better 3 shot group. Maybe start at 33.2 and do a ladder test at 33.2, 33.5, and 33.8 if no pressure was there at 33.5.

Not super familiar with the 6gt but I'm thinking of should run a tad faster than 2850-2900

OCW looks for the three loads that have the closest POI - not the group with the smallest size.
The idea is once the OCW powder charge is identified, accuracy is improved through seating depth.

 

[CharlieNC]

32.0 to 32.9 is where the vertical poi is flat, explore seating depth in the middle around 32.5.

 

[jelenko]

Sorry, my vote is it is either the loading, wind, or just all within the dispersion.

There is too much back and forth between AZ and EL between steps.

That would mean no load stability, or, it is all within the dispersion, or there was a problem with the test. I would keep working on it but either the gun, the load, (or both) is/are not ready to show us any sweet spots.

I wouldn't despair, if we aggregate all those shots and consider the charge range, it means the rig will be okay, just probably not in the 2s or 3s yet.

BTW, When you only have three shots, you don't need to bother with calculating SD, the AVG and ES is enough.

Make sure you are either shooting round robin, or watching wind flags, preferably both. Good Luck and in for the range reports.

Well, that takes care of my guess at 32.6

 

[jelenko]

32.0 to 32.9 is where the vertical poi is flat, explore seating depth in the middle around 32.5.

Is it just vertical? I thought OCW was done on both vertical and horizontal. But, I am no where expert on OCW.

And, to clarify - when I do an OCW, I shoot prone with a sling - 1/2 MOA groups are just great for me.

 

[RegionRat]

32.0 to 32.9 is where the vertical poi is flat, explore seating depth in the middle around 32.5.

The vertical POI is cold comfort if/when the azimuth is shifting in a short range test. Look at how far to the left that 32.0 group sits, the groups go left, right, left, right for every step?

 

[Checkmate101]

I should have mentioned, it was quite windy today and switchy. I tried to wait for conditions, but did not have flags. For a variety of reasons I couldn’t wait for better conditions to shoot in.

Certainly not a perfect test, but more trying to utilize these shots rather than just break the barrel in without gaining any knowledge as I go through it.

 

[RegionRat]

I should have mentioned, it was quite windy today and switchy. I tried to wait for conditions, but did not have flags. For a variety of reasons I couldn’t wait for better conditions to shoot in.

I'm not surprised.
No worries. It is all part of the game. Few of us are trust fund babies or have our range on our own property.

When you round robin in wind, you tend to need more shots to even out the odds of bad luck on three shots for any given step. By the time you go around more than 3 times, the chances you got a singular direction on every shot for a given step is greatly reduced.

It does help to run this on a calm day, but still get some wind ribbons or flags to be able to make note if you missed a big shift.

Like I said earlier, the gun will do fine but we don't know from this test if it can do great. Taking all the shots in composite tells us as much as all the rest. Be patient, you will get there.

 

[Bill Norris]

I'm not surprised.
No worries. It is all part of the game. Few of us are trust fund babies or have our range on our own property.

When you round robin in wind, you tend to need more shots to even out the odds of bad luck on three shots for any given step. By the time you go around more than 3 times, the chances you got a singular direction on every shot for a given step is greatly reduced.

It does help to run this on a calm day, but still get some wind ribbons or flags to be able to make note if you missed a big shift.

Like I said earlier, the gun will do fine but we don't know from this test if it can do great. Taking all the shots in composite tells us as much as all the rest. Be patient, you will get there.

Totally agree concerning the wind. Not too long ago Bart scoulded me about not using wind flags and I listened to him. It does make a difference especially when one is trying to test. I won't ever attempt to test again without at least a surveyor's ribbon stapled to a stake. Simple but it works.

 

[RegionRat]

Not too long ago Bart scoulded me about not using wind flags and I listened to him

Yup, guys like Bart forgot more about shooting than some of us are ever going to know....

 

[Bill Norris]

Yea when one of those will take the time to get on the phone with you and try to help it pays to listen no doubt.

 

[Clancy]

But, 32.0 is left of the POI. 32.3-32.9 looked like they had POI's closer

Left and right isn’t important if you’re just looking at vertical POI, which is what matters in a GT, or matters to me anyway.

But, when his barrel speeds up, 32.3 will be more like the 32.6 that some of y’all liked. (I may be the odd man out, but the better our barrel quality gets, the less I’ve seen then speed up. Not much of that 50-100 fps stuff anymore.

I don’t think he can go wrong in the 32-32.9 range. The barrel is just a baby anyway.

 

[Bc'z]

Left and right isn’t important if you’re just looking at vertical POI, which is what matters in a GT, or matters to me anyway.

But, when his barrel speeds up, 32.3 will be more like the 32.6 that some of y’all liked. (I may be the odd man out, but the better our barrel quality gets, the less I’ve seen then speed up. Not much of that 50-100 fps stuff anymore.

I don’t think he can go wrong in the 32-32.9 range. The barrel is just a baby anyway.

I'm liking 32.3 as well

 

[Clancy]

@Checkmate101 if you’re working with a cartridge that you’re comfortable with, I’d recommend doing seating depth first 100% of the time. It’s way more important, and it’ll make these tests easier to read.

If I work with something new, I’ll run 5-10 rounds of powder just to make sure I’m safe and within my expected velocity range, then I’ll do depth testing followed by powder.

But, you’re gonna make out fine on this one either way.

 

[Checkmate101]

@Checkmate101 if you’re working with a cartridge that you’re comfortable with, I’d recommend doing seating depth first 100% of the time. It’s way more important, and it’ll make these tests easier to read.

If I work with something new, I’ll run 5-10 rounds of powder just to make sure I’m safe and within my expected velocity range, then I’ll do depth testing followed by powder.

But, you’re gonna make out fine on this one either way.

I had read about depth testing first recently. I chose the powder first this time because I was changing a bunch of variables. Alpha brass instead of hornady and a new barrel/reamer as well. So I wanted to make sure things were safe and also get some velocity data at the same time.