6mm ocw test

[Regnar]

The stock savage Fclass in 6mm br came in last week and did my initial load development today. I got all my reloading supplies and equipment in on Thur and started making some rounds right away. I have varget and H4895 for powder, BR4's, 450's and 205m's. I have 100m each of berger 108 bt, 105 vld and 10.0 106gr BT bullets along with 300 pieces of la I am using a Lapua brass. I am using a redding FL Busing die, a Wilson seater with VLD stem, and an Annealeeze Annealer. I use a Forester Datum Dial to measure shoulders and CBTO. Powder is measured in a Charge master and then trickled on to a gem pro 250 with an omega truckler. Primers are seated with a RCBS hand primer.
Savage F class, 6mm br, stock,(30in barrel with target accu trigger)
Night force 12x42 br scope
Grizzly wishbone rest
Proctor rear bag
First OCW test consisted of 28gr thru 29.5 grains of H4895 I n .3gr increments behind a Berger 108bt shot at 100 yards. with virgin brass resized.


top left target and bottom right two were used for sighters. Two rounds from the initial sigh in impacted on the 2nsd target from the right on the middle row. 28.3 and 28.6 thru flyers that were not called. When I started on 28.9 I realized that I had the rifle in a different position on the front rest. At the end of the ocw I fired on more of the correct charge at the appropriate target. Based on this test I think I had a node at 28 and 28.9. I went home and loaded 28 thru 28.3 in one gr increments as well as 28.9 thru 29.8 in 3 gr increments. Based on the second session I think I have confirmed a node at 28 and 28.9 as well as 29.8. I may go higher as I had zero signs of pressure. All shots fired at 1min 30 sec intervals.
What do you guys think?

 

[Tim Singleton]

Don't take this to badly. But here goes
I know a lot of people use and like the ocw method.
I personally don't see its usefulness. That's a whole lot of bullets and powder burnt on one seating depth. I don't know of any benchrest shooters short or long range that use such a method. They all recognize the importance of finding the correct seating depth

 

[Texas10]

I suspect that after a couple of hundred rounds down the tube, your stock Savage will begin to settle down and shoot more consistently, and hopefully stop being a copper mine.

When I put together my Savage 6mmBR and began shooting ( with X-caliber barrel) , my targets looked pretty much as yours do. Like you, I was working up a charge using a consistent seating depth, but kept getting two hole looking groups out of three shots. How do you pick out a good load when you are putting two bullets through the same hole at more than one powder charge? LOL

So after shooting the OCW test, I shot the same loads (5 per this time) over my chrono. I picked a load that produced a decent group, had a low, single digit SD and a velocity around 2880 fps. which seems to be the magic number, then started adjusting the seating depth.

I'm not there yet, but this week made a 10 shot group that measured 100 with 6 X's at 300 yds on a gusty day with no wind flags. Oh, and using a 105 A-Max and Varget, CCI 450's and Lapua.

The A-Maxs have been discontinued, so before they're all gone, I bought 500 Berger 105 hybrids on sale, and they're next on the agenda. Want to compare the two.

Looking at your targets, I would take the 29.8 and do a seating depth study. Then take those results and work up slowly in .1 gr increments to 30.3 or beyond perhaps.

I hope my experience helps you in your load development.

 

[Regnar]

THanks. i was wondering how high I could go before expecting to see pressure signs.

 

[pat fulghum]

The only thing I would do with a barrel that has < 75 rounds is try to understand pressure and lands movement. Your node will move until barrel settles in. Don't settle on a load until you get 150 rounds done the tube.

Did you run an expander down that brand new brass before you loaded it?

Quoted several times "if it don't shoot 30.0gr Varget over CCI450 with 105 Hybrids at .010 off the lands...."

Start low and work up.
Shoot over a chronograph and you are looking for around 2880, but your barrel might speed up after 100 rounds.

Also I like to shoot my 3 shoot groups at normal pace, I do not shoot round robin anymore.

Just my .02 worth

 

[Tim Singleton]

I don't think you will see the full potential without finding the right seating depth
The OCW method seems to put the charge weight as the point of emphasis
I have to disagree with this method. At least in the search for extreme accuracy
The seating depth should be first and of most importance then a secondary process to narrow down into the powder charge window

 

[Regnar]

The only thing I would do with a barrel that has < 75 rounds is try to understand pressure and lands movement. Your node will move until barrel settles in. Don't settle on a load until you get 150 rounds done the tube.

Did you run an expander down that brand new brass before you loaded it?

Quoted several times "if it don't shoot 30.0gr Varget over CCI450 with 105 Hybrids at .010 off the lands...."

Start low and work up.
Shoot over a chronograph and you are looking for around 2880, but your barrel might speed up after 100 rounds.

Also I like to shoot my 3 shoot groups at normal pace, I do not shoot round robin anymore.

Just my .02 worth

I chose H4895 to start with because while researching this I found a load that German Salazar said was good so I figured I would try it.

I do not shoot round robin either. I shoot 1 shot every minuet and 30 sec.

YEs ran the brass through the expander.

I Am going to put the magnetto speed on and look for that node.

 

[Regnar]

I don't think you will see the full potential without finding the right seating depth
The OCW method seems to put the charge weight as the point of emphasis
I have to disagree with this method. At least in the search for extreme accuracy
The seating depth should be first and of most importance then a secondary process to narrow down into the powder charge window

I Use the ocw test to find a good node, verify with chrono data. then I work on seating depth. that process has worked very well on a few rifles. this also allows me to get some trigger time on the gun, learn what it likes, and get in the neighborhood of a load for when the barrel settles in.

 

[Tim Singleton]

I Use the ocw test to find a good node, verify with chrono data. then I work on seating depth. that process has worked very well on a few rifles. this also allows me to get some trigger time on the gun, learn what it likes, and get in the neighborhood of a load for when the barrel settles in.

I'll say this then leave it alone.
That node you identify is married to that seating depth that may or may not be even in the ball park

 

[Regnar]

NOt sure what you mean. unless I have been compmetely wrong in the past, the node is more closely asscoiated with the velocity. each barrel is different tbus the need for a test. you are not looking for a group in an ocw test but rather similar verticle dispersion over a couple different charges thus decreasing the effects of temps. once the node is identified then you play with seating depth to tighten it up. most of the time I have been able to get almost 1 hole groups at 100 and 1/2 moa 600 when i do my part.

IT is also my experience that you tipicilly see the the best sd and es numbers right around a node.

 

[pat fulghum]

Start here....

 

[Texas10]

I believe he is advising that a node is dependent upon velocity, which is dependent upon seating depth. Changing the seating depth effects the distance the bullet had to travel before it exists, therefore the time, and it also effects pressures, which also influence travel time.

Or maybe I'm the one getting too old and feeble.

 

[Regnar]

Start here....

EXactly what I said but in a much better and more detailed explanation

 

[dlwheel]

What has worked for me is to load up 4 sets of identical ladder tests in .3g increments in the reasonable range. These are shot at 600 yards over a chrono. I shoot two sets and my son shoots two sets.
Inevitably we will have three, maybe four, which will stack vertically at 1.5" or less... on all four sets.
Since I have chrono'd everything I can go back and check ES's for each of the 7 or so loads that made up the ladder.
The best ES's and SD's will almost always confirm the node.

From there I load the middle of the node and work on group size with seating depth.
When the barrel speeds up I stay with my node. And later may do another test to see if there is a node at the higher end.

 

[Regnar]

I Have not tested at 600 yet because i have been lazy. I know I need to do it and will start with this rifle. i like the way you do it.

 

[rifleman700]

I agree and understand both sides of the debate here when it comes to OCW and just seating depth first testing. They will both work fine but with the seating depth first method you will reach your rifles max accuracy potential. Having said that the tune window most times at this point is very small and takes constant tweaking to keep it in tune in most cases I have seen in my testing. If I was shooting BR this is the method I would use but for everything else I use the OCW method. With the OCW method I can usually find a nice big fat tune window in both powder charge and seating depth.

I have competed in many disciplines in the past and each one did not require gnats ass accuracy. For example my PRS / practical rifle shoots in the ones but if it only shot in the fives that would be good enough for this discipline. Consistency over out right accuracy. With my varmint rifles I use the OCW because I want to be able to shoot in any condition, same with my hunting rifles. And these are all half moa or better OCW loads.

If you want your rifle to perform at its best then use the seating depth first method. If you want a go to anytime rifle then go with the OCW method. This is all my opinion and others may have had different experiences with each but this is what I have found through the years in my testing.