2 OCW. 2 Rifles. 1 Load?

[pmclaine]

Made up an OCW using same charges for two rifles. I load on a Dillon S1050 and if I can get a charge weight that will work in both rifles life will be a little bit easier. Powder is 4064. Projectile is Nosler 168 CC, Win LRP, WCC 13 1X fired brass, COAL is 2.8.

In the sighter block I fired 5 rounds of a commercial remanufactured Atomic brand ammo loaded with a Nosler 168 CC over Varget to a 2600 fps spec. To make sure my reloads would fall inside the aiming square I shot another 5 sighters of 4064 at 42.4 grains. The rest of the charges started at 41.6 and increased by two grains to 42.8. Targets were shot round robin. I shot at a slow cadence never letting the barrel warm greater than it was comfortable to touch. Notes about dope changes, called bad shots and my loss of sack are as noted on the targets.

First rifle is a M40A1 spec build - R700, 24 inch Schneider Barrel, McMillan stock. Scope is a Weaver K10 temporary while I wait for the USO MST100 build to happen.



Second rifle is a LMT MWS, 16 inch chrome lined. Scope is a S&B 5-25x56. Odd thing about this rifle is it refuses to show a five shot group. It insists on putting one round inside one of the previous rounds.



I'm liking the 41.8 to 42.0 area in both rifles. 42.6 to 42.8 looks like it also has promise.

I load on a progressive but I pull my case after the powder drop and trickle to charge weight. Im thinking of loading between the two charges so that when I trickle if Im a kernel high kernel low it really shouldnt effect POI.

Im liking 41.9 based on most of my shooting will probably be 300 yards, with maybe 600 yards once a month and up to 800 yards infrequently. The lower charge will save my brass over time.

Do the OCW educated see anything Im missing? Does it appear I would be better off with loads tailored to each rifle? where do I go from here?

One other factor. I use a beam scale. It sits on a laboratory level platform and I zero it when I set it up. Thing is when I use RCBS check weights to check it, it seems to weigh minus .3 grains. So my 42.8 may be 43.1. Knowing my charges are not near max I did nothing to compensate and loaded assuming from zero a scale reading was correct. It is consistent in its error. I can weigh same charges and they will show same result. I guess I need to get a tuned scale but for right now Im considering it accurate. I actually have more faith in the Dillon beam than the RCBS weights. Checking a 168 Nosler CC the weights are within .1 grn +/-.

Thank you.

 

[gordonm1]

this is not a large spread of charges like three grains or something else. I'm new to the OCW analysis method so I can only say your 41.9 or 41.8 would be good to try to repeat the accuracy in another session. OCW seems easier to apply in a larger spread of charges.

 

[Drifter™]

Have you tried adjusting the COL for one rifle or the other?

I had a load that worked in two different rifles, but at different COL's. So I loaded everything to the longer COL, and simply re-seated to the shorter COL as necessary when it was time to shoot the corresponding rifle. I even kept a seating die and Lee hand press in my range bag just in case I needed more ammo for the rifle that preferred the shorter COL.

Not as ideal as a completely identical load, but it was the only way I could get the desired accuracy in both rifles without using different recipes.

You might could make ~41.9gr work well in both with a little COL experimentation.

 

[Twoboxer]

. . . I'm liking the 41.8 to 42.0 area in both rifles. 42.6 to 42.8 looks like it also has promise. . . . Im liking 41.9 based on most of my shooting will probably be 300 yards, with maybe 600 yards once a month and up to 800 yards infrequently. . . .

I came to 41.8-41.9 before reading your own conclusions. I think this is also supported by the scattering that occurs around 42.4gr which is about where you could expect it. Not knowing what your max safe load is, I'd be looking for another accuracy node theoretically at 43.0+.

So I'd shoot 41.8. 41.9. 42.0 expecting/hoping to see similar POIs, and if your safe max allows and if you are interested in a higher node . . . 42.8, 43.0, 43.2.

 

[JRM83]

Yes it is common to find a load that works in multile rifles. I haven't found a rifle yet that won't shoot 42.5gr of Varget under a 168 Nosler. I agree that 41.8-42.0 is promising. Both charge weights have the same POI and accuracy is good. The node seems extremely narrow though. Part of an ocw load is charge weight insensitivity. Find a few charge weights that shoot to the same POI and then tune the accuracy with seating depth changes.

Here is a link to Dan Newberry's OCW instructions: OCW instructions - Dan Newberry's OCW Load Development System

On your bolt gun the centers of all the groups are actually very close to each others which means the poi is the same. If you tune the seating depth you might get a larger node? On the LMT somewhere in the 42.4-42.6 area the POI jumps up. That suggests that the node below around 42gr might be a bit wider since 42.2 also had the same POI.

 

[pmclaine]

IMR shows start/end as 43/45.

Both seem high.

I developed basing off 42.8 being the FGMM clone loading. I tried some 42.8 and was getting some signs of pressure in the bolt rifle. I was surprised by this and thats what had me check my scale concerned that I was getting heavy loads.

42.8 is a pretty full loading in my WCC 13 case. Im impressed if IMR goes to 45.

 

[ChrisBCS]

pmclaine, barrel whip via the shape of the group definitely seems to be 42.0 for both rifles. No sign of the "triangle".

 

[pmclaine]

Meh!, No great joy in reloadingville.

I loaded up 41.9 grains of 4064 under a 168 Nosler CC - 25 rounds for the M40A1 and 24 rounds, minus one for a crushed primer, for the MWS - to shoot at 300 yards. The Shoot-N-See's are 6 inch diameter. All shots in the Shoot-N-See at 300 would equate to a two inch hold? Sadly I cant hold two inches save for during my alone quality time.

The M40A1 showed a liking for this load



what I typically get with Atomic remanufactured 168 Nos CC over Varget at 2600 fps



and for more comparison 5 rounds of Fed GMM 168 at 300



The MWS wasnt as accepting of the load at distance as it was at 100 yards



I had to mess with my dope some but even still it didnt seem to want to group tight. This is what I get at 300 with the Atomic 168 ammo



I dont expect the MWS to outshoot the bolt rifle but Im hoping for better. I think I should stick to steel with the semis. Ill be shooting my Garand on Wednesday Ill have to compare 300 yard results with the AR semi.