Load work-up 8208 XBR and L155 Scenar by OCW

[schwim]

Was getting north of 2900 on the last 2 charges with a 20 inch barrel (AI AE MKII). Chrono was sporatic with bad light conditions here in MI, so many rounds did not register. Highest I saw was 2926 with 45.6 gr. Had no pressure signs that I could detect. Did get one of the 45.9's to register, but it was less at 2907. A little odd maybe?

Looks like 45.6 is my load, no? Maybe I could try one increment higher and make 45.9 my go-to if the POI stays close to the lower ones? Thanks for any input you may have interpreting these results. Target 10 was for the sighters. I'm amazed at how the POI changes.

 

[schwim]

Re: Load work-up 8208 XBR and L155 Scenar by OCW

Forgot to give Dan Newberry credit for OCW, as requested on his website:

http://optimalchargeweight.embarqspace.com/

 

[diriel]

Re: Load work-up 8208 XBR and L155 Scenar by OCW

What I am seeing is a Lower Node, and an Upper Node. 1-4 seem to be the lower, and 6-9 seem to be bunching up at a reasonably similar POI. To me 5 seems to be the "Scatter Node", normally 1 or 2 up from that is considered to be the place to be. I think I would investigate 7, play with the seating depth and find optimal seating position and see how accuracy comes together for you.

Have a good one,
Gary

 

[schwim]

Re: Load work-up 8208 XBR and L155 Scenar by OCW

Thanks, it's cool to see how the flier from 5 grouped with the POI in 6. Was also interpreting the scatter at 5.

 

[Unsichtbar]

Re: Load work-up 8208 XBR and L155 Scenar by OCW

I have shot over 2000 rds L155 8208xbr Lapua case 2950 fps in a DTA SRS 22" barrel, 8.4 mil 1000, 3.4 mils 600yd. My orginal OCW test is a copy of you test. Suggest # 8 play with seating depth 6-9 OCW POI stable.

Last 600 yd shoot on F class traget 3" x ring shot a 7 first round because of 180 wind direction shift 12mph, then cleaned it 197-8x.

 

[schwim]

Re: Load work-up 8208 XBR and L155 Scenar by OCW

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Unsichtbar</div><div class="ubbcode-body">I have shot over 2000 rds L155 8208xbr Lapua case 2950 fps in a DTA SRS 22" barrel, 8.4 mil 1000, 3.4 mils 600yd. My orginal OCW test is a copy of you test. Suggest # 8 play with seating depth 6-9 OCW POI stable.

Last 600 yd shoot on F class traget 3" x ring shot a 7 first round because of 180 wind direction shift 12mph, then cleaned it 197-8x.

</div></div>

Awesome rig, are you also shooting .243 or magnums with it? Happy in general?

 

[Unsichtbar]

Re: Load work-up 8208 XBR and L155 Scenar by OCW

Very happy with DTA a bit of a learning curve for me had to get accustom to no trigger over travel stop. No shooting .243 but .300 wm and have shot .338LM.

You are going to really like this 8208 thing, ajust seating depth both back & froward to bring it in. If you wind up at 45.6 gr suggest FL size, shoulder back .0015, anneal 5th firing, watch primer pockets tighten up RCBS swedge die if multi loads.

 

[Bronco]

Re: Load work-up 8208 XBR and L155 Scenar by OCW

Schwim,
What brass are you using and primer.

I've been shooting a 155 scenar with 8208 since it became available. LC match brass, fed. match primer, 42.2 gr. netting 2920 fps. out of a 24" Krieger. Single digit sd's and 1/2 moa.

Also use it for 6 Dasher and 6 RAT loads as well as .223.

Just got some .308 Lapua brass so will be working up a load using it.

 

[schwim]

Re: Load work-up 8208 XBR and L155 Scenar by OCW

This was with CCI BR2 primers and virgin Lapua brass. Seating depth was .015 off the lands per my measurements using the Hornady LNL tool with their supplied modified (unfired) case. I'm guessing once I cycle through all the new brass, in the fireformed cases the bullet may have a slightly longer jump to the to lands when loaded, so will re-evaluate when this comes to pass.

Do people recommend changing seating depth in .005 increments, or is this too coarse? I will not be jamming, obviously for the safety hazzard, and hope that anyone who sees this post and tries to do what I did realizes the risks involved and carefully measures for jump (and does not go over book max charge, at your own risk). I don't feel safe going closer than .010 either. The boattail of the bullet is seating into the charge, so may be compressing it, but not sure of the exact definition of how to determine compression in this setting. It is definitely displacing it though.

Used the Sinclair bullet meplat trimmer/uniformer, and think .010 to lands is likely the closest I could get as allowed by magazine length. .015 may not have been doable without the trimming cause the tips are very close to the mag length now. I trimmed about .005 off the tips just to uniform them.

 

[MitchAlsup]

Re: Load work-up 8208 XBR and L155 Scenar by OCW

I like the whole range between 44.6 and 44.9. You should investigate to see if the whole range shoots well. If so, you you have found a throw and go long range load, just set the thrower to the middle of the range, verify thrown weight, and go to town.

0.005 is a fine step size for bullet seating experiments. {But based on the above (wide CW range), it is likely you wan't find much with the seating experiemnts.}

 

[vman]

Re: Load work-up 8208 XBR and L155 Scenar by OCW

I would throw a little more investigation into 45 to 46.2 gr and everything inbetween.

If it were me I would then take those rounds and go out a lot futher with them, perhaps 400 to 600 yards. Set up some larger targets for each one and see what happens. If any one charge is better than the next you would hope it is more obvious at longer ranges.

 

[Unsichtbar]

Re: Load work-up 8208 XBR and L155 Scenar by OCW

Suggestion Start .020 off lands with your possible OCW load, move both directions in .005. Being close to lands is not a guarantee of improved accuracy, it is where it is. Every one has there own method, as a general observation 155L like some jump but every rifle is different. Compressing the load is not a undesirable thing, seating depht ajustment are ajusting internal volume and severl other factors.