OCW interpretation help

[BigTex]

Ok, I ditched the FC brass and loaded up some Lapua brass to re run the test with. The bullets were 178gr Amax, the powder was Varget, and the primer was CCI-BR-2.

It's hard for me not to like 45.1 and 43.3 just based on group size, but I know that's not what we're looking for in OCW. What do you guys make of this test? I'd just like a second opinion.

 

[BC 6.8]

If you read about where Dan talks about the scatter node in relation to the OCW node, he says the OCW node is generally 1 to 2 increments above the scatter node. I would say your scatter node is 44.5 gr, so your 45.1 gr charge wt. could be the right load. You would need to go further and load up one round at 44.8, 45.1, and 45.4 gr and shoot them into one group to see if you are right.

 

[BigTex]

Thanks, I was hoping to find a lower node too. I might work around 43.3 as well and see what that does.

 

[damoncali]

It's hard for me not to like 45.1 and 43.3 just based on group size, but I know that's not what we're looking for in OCW.

Before you go down that road, think about that for a moment. If you're shooting big groups that are consistently hitting the same POI, that's not very useful, is it?

Nobody ever believes me on this, but I'll try again just in case I can save someone some ammo. OCW or ladders or whatever other vibration trick you want to use will not tell you what load will shoot well. They just won't. There are too many other things going on for this one effect to be so dominant. You have to shoot some groups and accept that there's going to be a little uncertainty as to which load is truly best. I have shot groups that totally defied the thinking behind OCW, and yet were consistently and substantially more accurate than whatever it was OCW would have told me to focus on.

And yes, I know what OCW is. That is always the first thing to come up when I suggest this.

 

[trailrider121]

Looks like 43.9 is low node and high node is 45.1 . I like the horizontal or 43.9 load

 

[Pinecone]

43.0 - 43.3 are similar POI. But so is 43.6 and 43.9.

I would work in the 43 - 44 range again.

Then once you hit the accuracy node, then work in seating depth. That will shrink the groups with the right charge weight.

 

[Pinecone]

The point of OCW is to come up with a powder charge that will shoot good groups with slight variations in conditions. Finding the ONE powder charge that shoots a really small group, but if anything changes, the groups blow out, is not that usable in the long run.

 

[BigTex]

Don't know if this changes anything, but these are the first 2 shots in each group.

 

[Twoboxer]

LOL! I didn't comment on your first pic, because I was confused and wanted 44.2 and 44.5 Not to have (what turned out to be) that third shot.

Did you clean the barrel at any time during shooting? If so, did you run foulers before shooting OCW again?

If the answer to either of those is no . . . or if you just got nervous about so many close pairs lol . . . then I'd be looking between 43.9 and 44.3 for comfort The area at ~>43.0 looks OK and is nearly 3% lower somewhat supporting 43.9-44.3

 

[kvwpwr]

I would rerun the test around 45gr. That is a common ocw load. It's what I settled on for 178 amax. I wouldn't be surpised if the other groups around 45 were just your shooting. If you do plan on shooting long range then a lower node would be fine too

 

[timelinex]

Ok, I ditched the FC brass and loaded up some Lapua brass to re run the test with. The bullets were 178gr Amax, the powder was Varget, and the primer was CCI-BR-2.

It's hard for me not to like 45.1 and 43.3 just based on group size, but I know that's not what we're looking for in OCW. What do you guys make of this test? I'd just like a second opinion.

To be honest with you, this doesn't look like its showing too much information to make a good decision based of OCW principles. They are really all in the same POI. It looks like if you just loaded all those rounds in at random and shot 3 rounds groups, you would probably get close to the same average group size!

If 44.5 gr and 43.6 didn't just have a pulled shot, then that would be your scatter nodes most likely. The accuracy node is generally right before or after. If you want to go based off that and you want a lower pressure node then I would load 5 round groups of multiple seating depth variations of 43.2. Run it over a chrono. Find the one that groups the best and has the best SD's (if shooting long distance) and call it a day. Lastly I would just confirm the node by shooting a couple groups using your new seating depth and with charges of 43,43.2 and 43.4. If they are all good groups that you have a nice resistant accuracy load.

 

[BigTex]

Update:

I think I like 45.1

ETA: This target was vertical when it was shot.

 

[BigTex]

LOL! I didn't comment on your first pic, because I was confused and wanted 44.2 and 44.5 Not to have (what turned out to be) that third shot.

Did you clean the barrel at any time during shooting? If so, did you run foulers before shooting OCW again?

If the answer to either of those is no . . . or if you just got nervous about so many close pairs lol . . . then I'd be looking between 43.9 and 44.3 for comfort The area at ~>43.0 looks OK and is nearly 3% lower somewhat supporting 43.9-44.3

No cleaning. Maybe fatigue.

 

[BigTex]

To be honest with you, this doesn't look like its showing too much information to make a good decision based of OCW principles. They are really all in the same POI. It looks like if you just loaded all those rounds in at random and shot 3 rounds groups, you would probably get close to the same average group size!

If 44.5 gr and 43.6 didn't just have a pulled shot, then that would be your scatter nodes most likely. The accuracy node is generally right before or after. If you want to go based off that and you want a lower pressure node then I would load 5 round groups of multiple seating depth variations of 43.2. Run it over a chrono. Find the one that groups the best and has the best SD's (if shooting long distance) and call it a day. Lastly I would just confirm the node by shooting a couple groups using your new seating depth and with charges of 43,43.2 and 43.4. If they are all good groups that you have a nice resistant accuracy load.

Thanks for the input!

 

[Pinecone]

The upper left group certainly flies in the face of those weighing to 0.02 grains.

 

[BigTex]

Atleast for my load/rifle combo it does. I think I found a pretty forgiving load.

 

[waveslayer]

First off 100 yards is way way too close. That is like shooting a .22 at 50 yards getting ragged holes and expecting that same .22 to shoot ragged holes at 100, 150 yards!. A minimum for a ladder test or OCW is at least 300 yards. Then your next round is 400 and the next 500. Your best loads were 43.3, 43.9, 45.1. I have a load that shoots an inch grouping at 300 but at 100 it is just over 1.5 inches.. you need to run 43-45.2 with .2 increments in charge weight at 300 and then take those good groups to 400 at .1 grain increments....etc.. Also you are looking for vertical stringing so 43.9 looked like an excellent load besides the other 3 loads I picked.

 

[waveslayer]

Watch this and you will see what I mean. This works great..http://m.youtube.com/watch?v=c5SmiMSF20A

also check out Tres at Wilderness Means - Survival Training and Rifle Training

 

[BigTex]

I'll shoot at 300 and maybe 600 and 1000 today to confirm. I loaded 50 rounds of 45.1 to take to the range.

 

[shoot4fun]

First off 100 yards is way way too close. That is like shooting a .22 at 50 yards getting ragged holes and expecting that same .22 to shoot ragged holes at 100, 150 yards!. A minimum for a ladder test or OCW is at least 300 yards. Then your next round is 400 and the next 500. Your best loads were 43.3, 43.9, 45.1. I have a load that shoots an inch grouping at 300 but at 100 it is just over 1.5 inches.. you need to run 43-45.2 with .2 increments in charge weight at 300 and then take those good groups to 400 at .1 grain increments....etc.. Also you are looking for vertical stringing so 43.9 looked like an excellent load besides the other 3 loads I picked.

Maybe you should actually read the detailed instructions for OCW. Google newberry OCW. OCW is initially done at 100 yards in round robin fashion. Ladders are typically done at 300 yards.

 

[shoot4fun]

I'll shoot at 300 and maybe 600 and 1000 today to confirm. I loaded 50 rounds of 45.1 to take to the range.

45.1 Varget with 178, it seems to me, is a hot load for Lapua brass (smaller volume) and TX temps.

 

[BigTex]

45.1 Varget with 178, it seems to me, is a hot load for Lapua brass (smaller volume) and TX temps.

Seems that way to me too, but it is showing absolutely no pressure, the case heads/primers are identical to the lower node loads. Both days that I have shot this load have been 90 degrees. I didn't even show pressure at 45.4gr.

 

[BigTex]

The 300yd group I shot today measured 0.951" ctc. I then shot steel at 600 and 1000 with excellent results. I think this will be my load for this gun.

 

[Pinecone]

First off 100 yards is way way too close. That is like shooting a .22 at 50 yards getting ragged holes and expecting that same .22 to shoot ragged holes at 100, 150 yards!. A minimum for a ladder test or OCW is at least 300 yards. Then your next round is 400 and the next 500. Your best loads were 43.3, 43.9, 45.1. I have a load that shoots an inch grouping at 300 but at 100 it is just over 1.5 inches.. you need to run 43-45.2 with .2 increments in charge weight at 300 and then take those good groups to 400 at .1 grain increments....etc.. Also you are looking for vertical stringing so 43.9 looked like an excellent load besides the other 3 loads I picked.

Step 8 of the OCW instructions:

8. At the range, you should set up 5 to 7 targets at 100 yards.

 

[RTK]

The 300yd group I shot today measured 0.951" ctc. I then shot steel at 600 and 1000 with excellent results. I think this will be my load for this gun.

]

That would be my load and I would be tickled pink with a better than 1/3 moa group at 300 yards

 

[Dan Newberry]

In all my years of working with OCW match loads (match bullets, at appropriate MV's for the max range intended), I've never seen even one properly identified OCW load fail to perform well at long range (even out to 1200 yards)--though it was initially developed at 100 yards.

We recommend 100 yard initial development to factor out wind effects. Many do ladder tests at 300 and farther, and disregard the horizontal. They are working under the false assumption that lateral dispersion is always going to be wind related; but we see horizontal at 100 yards, too... lateral at 300 may simply indicate the barrel's vibration pattern is inducing some horizontal into the group.

I'm glad this load is working out well. I will agree that it's on the warm side, no doubt. But if it's not showing pressure problems, you should be fine.

Dan

 

[Infinity]

Nice work OP. What is your barrel length? Did you chrono these loads?

I am getting ready to do this for my new rifle (20" barrel) with new Lapua brass, F210M primers, 178 Amax, and Varget....once that is complete, I am going to switch to 180 gamekings and run OCW tests again. Does anyone have experience with switching from Amaxes to Gamekings and how that affects pressure/velocity?

I don't mean to threadjack and am happy to write the op a pm if you gents find that more appropriate. Thanks,

Adam

 

[BigTex]

My barrel is 20" and I haven't chrono'd them yet, but that is next. I was shooting with my dad today and he was in a hurry so I couldn't set up the chrono. I can tell you they were 2 minutes high at 300yds and 2 minutes high at 600 yds when using 175gr GMM data in Ballistic AE.

Be sure to work it up yourself though, I am 1.1gr over book max for this load. Even though there is no pressure signs in my rifle, there might be in yours.

 

[Infinity]

Thanks for the reply. I will of course work up. Mongo no like accidental boom boom.

 

[shoot4fun]

My "standard" 308 load is 175 SMK, Lapua brass, FGMM primer and 44.7 Varget. I keep it at 2.80" COAL. It has shot well in almost every 308 I've owned and even worked well in my son's R700 5R rifle. I liken it to the Federal Gold Medal Match 168 as fas as performance level in a vast majority of 308 rifles.
Your load looks like it is going to be a good one and your rifle too.

 

[BigTex]

My "standard" 308 load is 175 SMK, Lapua brass, FGMM primer and 44.7 Varget. I keep it at 2.80" COAL. It has shot well in almost every 308 I've owned and even worked well in my son's R700 5R rifle. I liken it to the Federal Gold Medal Match 168 as fas as performance level in a vast majority of 308 rifles.
Your load looks like it is going to be a good one and your rifle too.

Not too bad for a factory Remington barrel.

 

[BigTex]

I clocked the loads today and they averaged 2560fps with an ES of 25fps and a SD of 10fps. Does this seem too fast out of a 20" tube?

 

[Infinity]

That sounds about right. Enjoy that load and that rifle...

 

[BigTex]

Stretched the 45.1gr load out to 825 last weekend. 4.9"

I have noticed that I see slight ejector marks if I fire more than one round in rapid succession. If I wait 30 seconds between shots, back to no pressure. Anyone ever experience this on a suppressed rifle?

 

[doctordoctor]

Here's my quick and dirty OCW with 40-42 grains of XBR. new lapua brass, BR2's and 175 smks factory 308. Poor conditions with pouring rain. My copy cat fgmm 168's shot great (42.8 gr 4064). anyhow In my unprofessional opinion it appears I need to extend the powder charge range. Or just scratch it using 175's and focus on a 155 xbr load. I have Varget, BLC-2, Reloader 15 and 4064 to test. I want to test h4589 if I ever find it. Thanks for the help guys. I hope the image is straight. it is on my end but i have noticed when I post they end up upside down or sideways!

 

[doctordoctor]

Bump.

 

[Dan Newberry]

It may be that the 8208 is developing too much pressure for consistent accuracy at the levels around 41.5 and beyond. You do appear to have a node which may be centered at 39.7 or somewhere in that area. I would say you'd do better with 4064 or Varget with the 175's, and then see how the 8208 does with the lighter bullets.

 

[waveslayer]

My little understanding is, XBR is ideal for bullets in the 150 grain range

Sent from my SCH-I545 using Tapatalk