Double Check my OCW results

[mzvarner]

Rifle is a Rem. 700 in 308 with 20 inch barrel 1 in 10 twist. I loaded 178 gr Amax over Varget from 40.5-45.5 in 1/2gr increments. Brass was 1 fired (now twice fired) Hornady match with a CCI 200 Large rifle primer. I set a target at 100 yards and began by shooting three sighters (40.5, 41.3, 42.1). I examined every case for pressure signs during the entire test. I never found any on the cases nor did the bolt ever get tight. I began by shooting 1 round at 40.5, feel barrel for warmth, shoot at the next POA for the corresponding powder charge, repeat. If the barrel felt warm I stopped for a few minutes. Once I reached the highest charge (45.5) I repeated the process but going from highest charge to lowest. Finally I went one more time from low to high to make 11 3 shot groups.

My best string is 42.0, 42.5, 43.0, 43.5. All were between 4 1/4- 4 7/8 inches from POA (in fact every group is about 4-5 inches RIGHT OF POA). owever these 4 groups were all sub MOA (.576- .853). I measured these by zeroing my calipers on an Amax first.

I am having difficulties deciding where to go next. 42.5-43.5 makes for pretty consistent group sizes, but 42.0 is the smallest. Currently I am leaning towards 43 (since its between 42.5- 43.5). Should I run it again from 42.0-43.5 in say .02 gr increments?

View attachment 22162

 

[Rprecision]

Its really hard to say with how everything laid out. It appears there is a node around 41 and 43.5

I prefer to shoot on a grid target or a OCW target as it makes things a little easier to point out. I also drop my charge weight changes to .3 for .308 size cartridges.

For reference I found my OCW 175 SMK Varget load at 43.3 grains with the exact same brass in a 10 twist gun.

I would zero and reshoot it around the 42.4 42.7, 43.0, 43.3, 43.6 and see what's what.

If you Google "OCW Target" there are ton for free download that help keep track of everything.

 

[Rem7targetactical]

I also agree that your powder charge increase may be too much to see where the nodes are. You may very well have jumped right over the scatter nodes. Try .2 or .3 increases.

 

[kvwpwr]

It's hard to figure out group locations when it's so far from your poa with no grid. You should make sure your scope is zeroed before you start the test.

 

[Rprecision]

Here's the targets I use most of the time

OCW OFFICIAL TEST TARGET in Handloading and OCW related topics... Forum

The most useful thing I have found is their size and the ability to record a lot of information easily

 

[mzvarner]

The scope is zeroed for 168 gr projectiles. I thought it was odd too, and tried to correct it with my 3 sighters however that didnt work. I then didnt want to change any variables. I loaded up fresh rounds from 42.4-43.6 in .2gr increments. I will adjust the scope before I leave and will shoot at the above linked target and see if that makes it easier.

 

[mzvarner]

So I re-did my OCW with Varget loads were 42.4-43.6 in .2 gr increments. I got the scope closer and printed off the suggested target. My shooting conditions were a little different and what do ya know, it looks like it made a hell of a difference in the wrong direction. Today I shot from a bench off a plywood table. My gun was bouncing "all over", where as last time I was on the ground prone with the bipod pretty well seated in the ground with barely any hop. Looks like 43.0 gr is pretty consistent, but if you compare it to what I was getting in the original post, i think its all S#!T and I am considering redoing this test in my original conditions. What do you guys think? Am I over thinking this? Should I just load 43 and shoot it?

View attachment 22402

 

[mzvarner]

So I loaded up some 43.5 as it shot well in both tests. Took it out today and my groups opened up to just over an inch at 100. Gonna just run the whole test again. 42.2-43.6 Varget in .2 grain increments.

 

[308Gunner]

43.6 looks pretty good I would load 5 of those and 5 of 43.7 and see what happens, then you can start with seating depth

 

[Rem7targetactical]

My 308 23.5" 1-10 LOVES 44. of Varget with 175 MK. Maybe you need to test higher charges?

 

[mzvarner]

My 308 23.5" 1-10 LOVES 44. of Varget with 175 MK. Maybe you need to test higher charges?

I am all for testing higher charges but I want to have a chrono with me before I go any higher. This is my first two reloading tests and am still a little nervous about pressures and what not.

 

[DroidSniper]

I am all for testing higher charges but I want to have a chrono with me before I go any higher. This is my first two reloading tests and am still a little nervous about pressures and what not.

A chrono is not a reliable indicator of pressure.

I look for flat primers and I measure the case pre and post firing. The case body just above the rim should not expandera greater than .003. I shoot Varget and 175SMK.178 Amax are prety well known for being money in .308. I use LC once fire brass and do ok with the Machine gun brass. When I can find LR head stamped brass those loads are pretty easy 1/2 MOA. My .308 is mostly for short range banging steel so I save the money and deal with 1 MOA accuracy with the machine gun brass. I am sure if I weight sorted it I could do better but I'd rather spend the time shooting.

 

[Rem7targetactical]

I am all for testing higher charges but I want to have a chrono with me before I go any higher. This is my first two reloading tests and am still a little nervous about pressures and what not.

My rifle is a Remington model 7 and 44. is a WELL known accuracy node for a 308 pushing a 175 MK. Here are some pics of my OCW test. You can see I went beyond 44. and I did not see any pressure signs (hard to lift bolt handle, ejector marks, flat primers etc..) ALWAYS slowly work your way up and look for signs with every increase! You still have a little bit to go before your closing in on a hot load with high pressures.

 

[mzvarner]

My rifle is a Remington model 7 and 44. is a WELL known accuracy node for a 308 pushing a 175 MK. Here are some pics of my OCW test. You can see I went beyond 44. and I did not see any pressure signs (hard to lift bolt handle, ejector marks, flat primers etc..) ALWAYS slowly work your way up and look for signs with every increase! You still have a little bit to go before your closing in on a hot load with high pressures.

Do you know what kind of velocities your getting around 44 gr?

 

[farmerbrown]

Gi'day,

Depends on temp and barrel length - for 25-26" barrel I get about 820 m/S = 2,690 fps with SD = 3 m/S or less (10 fps).
With colder temps (10C/50F) = 815/2675 and warmer (25C/78F) = 825/2710.

I used to use 44 gn with my 'tuned' Rem 700 PSS. After putting a new custom barrel on it, it definitely prefers a bit more powder (44.5 looks good for now).

Cheers

 

[Rem7targetactical]

Do you know what kind of velocities your getting around 44 gr?

Sorry but no, I don't have access to a chronograph and only go by results. The 44. on my test was nearly through the same hole and surrounding groups were all close to the same POI. I have not yet had a chance to get back to the range to see how it does at 200 but before this test I was shooting 1/2 to 3/4 moa at 200 using 42. so I'm hoping to see greatly improved results. Remember that these tests are giving you a general idea what your rifle likes and can be further fine tuned after you decide what charge you are going to use.

 

[mzvarner]

Remember that these tests are giving you a general idea what your rifle likes and can be further fine tuned after you decide what charge you are going to use.

I understand this principal. I thought I had a load figured out with 43.5 gr of varget. My last session I tested 4064, but before I left I shot a 5 shot group of 43.5gr Varget and it opened up to 1 1/14 inch. Two things had changed since my last test. I cleaned the rifle, and I used different brass. For the original test I used Hornady Match brass, but for the five shot I just grabbed 5 random cases (FC, Winchester, RP, a Hornady and something else). So either Rifle cleaning makes a big difference or the Quality of brass does. I am going to reload more and see if it is the brass I used and if so then I have a lot of sub match grade brass thats useless to me.

 

[Rem7targetactical]

Cleaning will make a change for the first 50 shots or so, you honestly only need to clean every couple hundred rounds or until accuracy diminishes. From what I've read and how I understand it is that when you clean, your removing the protective film on the inside of your barrel causing premature wear until it builds back up again. The random cases were your problem, they all have different internal volumes = higher and lower pressures. I started with Hornady brass and reloaded it a couple times but found it to be soft and the primer pockets loosened up. I switched to Lapua and never looked back, it's the most consistent and can be reloaded a dozen times. Winchester is really good from what I read too but have never tried it. I figure that if Lapua is supposed to be the best why not use it cause thats one less thing to worry about while striving for consistency. Sure it costs a little more, but if you can reload it 10+ times is it really more?

 

[1lnbrdg]

Another thought, when switching powders, there's usually a 2~3 shot variance before it settles down with the new powder. Almost all powders do this.