Help me interpret results ... OCW load development

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Tikka223

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Good day CGN wealth of knowledge.

I was out at the range today to try out a few loads after doing the "barrel break-in" for my Sako TRG-22.

Here are the results:

8C6824F0_zps873d5ad2.jpg


The loads:
Winchester brass (trimmed to 2")
CCI BR2 primers
H4895 powder
Berger 185gr Hybrid bullets
OAL: mag length (2.901" OAL)

I had planned on doing a ladder test like I often do but then came across the OCW (optimal charge weight) loading method and decided to try it (mostly because it was windy and because it can be a pain to keep track of bullets holes at 300m through a 24x scope). I shot the 10 charge weights into 3 shot groups in a round-robin way, making sure the barrel never got too hot to touch.

What charge weights do you suggest I work on? OCW says to play with seating depth but I'm more interested in being able to use the magazine.

In case you can't see the photo too well the charges from left to right are as follows:

39.8 40 40.2 40.4 40.6 40.8

41 41.2 41.4 41.6

Federal soft point cheapo hunting ammo (can't remember what bullet weight)

* I have no idea what happened on the 40.6 group, I really don't think I pulled the shot that high but my recoil control might have sucked. Then the third shot landed right on top of the first. The third shot makes me wonder if this is the "scatter group" or not.
 
I would pick 41.2, it's still within the node and possibly highest velocity, even if you go higher pressure/velocity due to temprature etc it'll still be in tune coz 41.4 doesn't have much verticle either. You can probably shrink those groups by adjusting seating depth. JMO
 
The whole point of the OCW test is to be able to shoot it at 100yds.

Anyway. I would look at 41-41.2, like Calgary said, and see how they group together at longer range. While you're at it run them over a chrony to see if the small increase in powder makes a noticeable difference in velocity. If your just looking for a cheap hunting load I would say you've found it.
 
I would look at the 41.2 although 41.4 strung out horizontally a bit. If you look at avg POI for 41-41.4 they are all very very close in reference to POA. This is what your looking for with the OCW method. 41.2 is in the middle of the 3 groups that share the same POA/POI relation. I would do a bit of seating depth testing and see what that gets you.
At least that's what I'd be doing
 
^ id do the same. Your looking at a fuller case with 41- 41.4 grains (which in my opinion is better for consistancy) and if it gets really warm your pressures should still be good.
 
41.8
42.0
No pressure yet
42.2
...
..
;)

The bullet you're using needs to fly fast. I'm thinking you'll be over listed max, before you see best results. This is where you write your own data.
Play safe.

Are you using the dot? That's a big dot.
 
I was aiming at the dot, and I agree it's on the big side, however, I could still see the cross hairs and was able to aim for the very middle of the dot.

Next time out with some new loads in the 41-41.2 range I'll be shooting at a greater distance (300m most likely) so the dots will be good aiming points.

I just bought a chrony too, so I'll be bringing it out next time I'm at the range and I'll see what velocity I'm getting.

If the 41 range works for me I may just play it safe. I'm sure the action can handle higher pressures but you'll have to convince me as to why it's worth it to go almost 10 grains higher. I'm pretty sure 41.6 was listed as a max for 185gr bullets.
 
You can go higher in charge weight then book because more then likely book lists load based on 2.800" OAL and you are running 0.101" longer OAL, more room in case means lower pressure and lower velocity hence you can add more powder to bring velocity back up and in most cases higher then SAMMI even with lower pressures. Read the following article(if you haven't already), it explains everything about COAL

http://bulletin.accurateshooter.com...n-cartridge-overall-length-and-base-to-ogive/


Tikka223 said:
I was aiming at the dot, and I agree it's on the big side, however, I could still see the cross hairs and was able to aim for the very middle of the dot.

Next time out with some new loads in the 41-41.2 range I'll be shooting at a greater distance (300m most likely) so the dots will be good aiming points.

I just bought a chrony too, so I'll be bringing it out next time I'm at the range and I'll see what velocity I'm getting.

If the 41 range works for me I may just play it safe. I'm sure the action can handle higher pressures but you'll have to convince me as to why it's worth it to go almost 10 grains higher. I'm pretty sure 41.6 was listed as a max for 185gr bullets.
Click to expand...
 
You mentioned doing a ladder test.
There is a ladder test in your ocw test, but all your charges are landing on the same vertical, or so close that it's hard to see the difference. That's why I don't think you've found your charge yet.
I think a ladder test at 300 will give more info than this test. It can also be done with 1/3 the components.

May I ask what manual you're using?
Thank you. What manual are you using?
:)

And lastly;
Have a look at the bearing surface on your 185's, see how short it is. Treat it like a lighter bullet, and write your own data.
 
I was referring to my Speer manual (it came with the press and it isn't the best).

I had originally planned on doing the ladder test at 300m but for whatever reason lately, the wind has either been coming from the 12 o'clock or 6 o'clock at the range lately and at 300 I'm worried it'll be too significant a variable to account for.
 
That's why you only take vertical in account when doing load test at 300m.
If I were you I would fire 3-5shot groups in 1/2 grain increments till you run into pressure, then take the charge weight with best groupings just under the load that showed pressure and test in more finer increments.1 to .2 grain around that. Once you find a good node and stay in the middle of the node. Now if you really want to, try changing seating depth for itty bitty groups. I don't mind load developments coz it gives me an excuse to get out and shoot.

If you don't like spending time and components do the ladder at 300-500, shoot groups with whatever shows good node and velocity. Take best grouping load and Do another ladder for seating depth at 600 to 1000m and stick with middle of the node again.

Tikka223 said:
I was referring to my Speer manual (it came with the press and it isn't the best).

I had originally planned on doing the ladder test at 300m but for whatever reason lately, the wind has either been coming from the 12 o'clock or 6 o'clock at the range lately and at 300 I'm worried it'll be too significant a variable to account for.
Click to expand...
 
Tikka223 said:
I was referring to my Speer manual (it came with the press and it isn't the best).

I had originally planned on doing the ladder test at 300m but for whatever reason lately, the wind has either been coming from the 12 o'clock or 6 o'clock at the range lately and at 300 I'm worried it'll be too significant a variable to account for.
Click to expand...

A head or tail wind isnt going to disturb your shot as much as you think especially between 100-300 yds. Id only be worried if you got a heavy heavy wind.
 
Tikka223 said:
How many MOA do you think a 20km/hr head wind would move a bullet at 300m?
Click to expand...

No field data so take it with grain of salt, 'Shooter' app(in my weather conditions) shows zero elevation change between 0 to 10mph headwind at 300m(calls for 1.5mil up in either case), at 1000m it tells me to add 0.1 mil to elevation when headwind changes from 0 to 10mph
Load is
308 win
178 gr HPBT
2630 FPS
 
Last edited:
Tikka223 said:
What signs of pressure do you suggest I look for? I've seen flattened primers in "normal" loads in some rifles.
Click to expand...

Every gun is different, minor flattening is ok, I go by flattened primer where head of primer is just as big as its diameter, ejector swipe and heavy bolt. Here's a video that shows some excessive pressure signs

https://m.youtube.com/watch?v=orJdUR_X67M
 
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