First OCW results help

G

gtrchase

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Minuteman
Jul 12, 2011
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Spring, Texas
#1
Working on developing a load for my rifle, and shot an OCW test yesterday. I'm having a little difficulty interpreting the data, and wanted some extra input here.

Remington 700 AAC-SD - .308
BC Light Medalist stock

Load:
Winchester Brass - 2 fired
Federal 210M
Varget
OAL- 2.80
175 SMK

Powder - 44, 44.3, 44.5, 44.8, 45, 45.3, 45.5, 45.8

I shot the center bull cold bore to confirm my zero, then shot 1-8, 8-1, 1-8 round robin style. I waited roughly 1 minute between shots. I feel fairly confident in my rifle and shooting ability, but feel free to critique that if it's obvious I'm doing something wrong. I've had consistent .5 MOA, with the occasionally .25 MOA 5-shot group with Federal Match Ammo.

7327845502_3a123a94f9.jpg


7327869064_b08a5e7c96.jpg


Purely looking at the data, I would reshoot with 45.5-46 in smaller increments since 45.5 and 45.8 are the most consistent POI (OCW rules) and the smallest groups. My concern is the powders are over book max, and if I adjust OAL to tighten groups, I may have a pressure problem. I had zero pressure signs at 45.5, and a hint of a shiny extractor spot on 1 of the 3 45.8gr rounds. No sticky bolt.
 
#2
Re: First OCW results help

I'd wouldn't rule out 45 to 45.3. You can see the POI shift up and could be moving into a upper node.

I'm assuming that you may of thrown the one shot in the 45 group and if that was true your view of the results might be different.

Personally I'd at least try the 45gr.again as a 5 shot group just to verify that it wasn't me.

Good luck.
 
#3
Re: First OCW results help

Sounds like a good idea. I'll reshoot the 45 groups. I'm more comfortable with that powder range. Is the 45.8 gr too high with the slight pressure signs I'm seeing?
 
#4
Re: First OCW results help

I have to agree with AtOne both 45.0 and 45.3 are above the 44.8 and 45.5. This node may have a small window of charge weight and thus not be a "real" ocw node. Don't rule it out until surveying it again.

45.8 might be too high or right on the edge depending on what pressure signs you actually do see. (Some pictures of the cases and primers would help out analysis.)
 
#5
Re: First OCW results help

So it looks like I'm reshooting. I tried to get some pictures of the fired brass, but it didn't show up very well. All brass looked the same. The primers didn't look any different, the 45.8 just had a light shiny spot from the extractor. It was faint, but definitely there.
 
#6
Re: First OCW results help

I don't see where a very very small hint of an ejector mark is a huge deal. Hell, I get them all the time, when bolt is sticky that's where I draw the line or finding loose primer pockets. 45.8 grains seems pretty damn hot for a 175. I mean really hot. Most I can get is 44.8 and that's out of a gap crusader. Whats your muzzle velocity?? Only reason I ask is I have an spst .308 that I shoot 168's out of. Mines a 1:12, I'm assuming yours is 1:10??? Also I would as if you've done an oal check to determine the distance to the lands. My throat is really really long. I load 168 vlds at 2.960". Sammi says 2.8 but sammi is not loading for my rifle. If you can get anywhere within 20 to 40 thousands of an " from the lands that might help but I'd check your powder charge weight bc pressure will spike. Smks as a general rule like a good little jump as mentioned above. But sometimes that jump is too much. I will say your 45.5 looks very promising but one thing I noticed is there is one shot in almost every one of your groups that is left of the rest. Especially the last 3 groups on the bottom. Almost identical. You think you were tired and pulled em or that was just the rifle? Good luck and hope you respond bc I'm thinking about getting same rifle
 
#7
Re: First OCW results help

The bolt was not sticky, and primers looked fine. Yes my twist is 1:10. I was planning on finding my load with the OCW, then running that load thru the chrono, so I don't know my velocity yet. I measured my OAL at 2.82, so I seated to 2.8. (I will re-measure that soon, I used the cleaning rod with stops method. Do you have an alternative way to measure?)

I agree, every group has one shot to left. The shot to the left of each group was the first shot in each group (round robin, so my first 8 shots) Maybe I was nervous getting started and didn't get settled.
 
#8
Re: First OCW results help

IMHO don't go over the 45 grain mark with Varget. My node was at 44.7 Varget, 175 SMK, FGMM 210 primer, Lapua brass, loaded to 2.84" OAL. This load has worked in every 308 I've shot it thru but one. That one was a 18.5" barrel.
 
#9
Re: First OCW results help

That's odd that those were your 1st shots. (left). To answer your question about oal, you can take a shot casing, crimp it just enough to hold the bullet solid but give it room to slide as you chamber it, and have it marked with a marker and that will show you where your bullet is hitting the lands. after that measure, and back it up however much you need to to get out of the lands and then start at .0040" off and work your way up to ".0010. If you find a .5 moa load then stop!!! That's probably as good as it gets. Don't waste your money anc time chasing it bc it will eat you alive. Crony it. Jbm it. Start pulling the trigger. Try different shooting distances, weather, and ranges. That's it!!!
 
#10
Re: First OCW results help

I haven't personally done any comparison testing, but doesn't Winchester brass have a larger internal capacity? If your load is 44.7 with Lapua, wouldn't that be over 45 with Winchester brass? Not trying to be an ass if it comes across that way, I'm genuinely curious. Trying to learn as much as I can.
 
#12
Re: First OCW results help

That's what I do. I have 5 solid long range rifles & scopes. I load one load for every one of them. Otherwise I'd be divorced, broke, and plain out pissed off all the time bc my " new" load won't shoot the way I want and I can't find powder charge, oal..... You get the drift. I will say 1 more thing then shutup, the more you shoot one particular load, you will get to know it, almost like you kind of understand it. Shoot it long enough and it will be brushing your teeth.
 
#14
Re: First OCW results help

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: gtrchase</div><div class="ubbcode-body">I haven't personally done any comparison testing, but doesn't Winchester brass have a larger internal capacity? If your load is 44.7 with Lapua, wouldn't that be over 45 with Winchester brass? Not trying to be an ass if it comes across that way, I'm genuinely curious. Trying to learn as much as I can. </div></div>

I would never attempt to extrapolate that 44.7 in Lapua compares to over 45 with Winchester. I have no pressure testing equipment. I will say that I have many firings on some of my brass (as much as ten) and it is still looking and shooting fine with no loose primer pockets. I do keep it cleaned, trimmed and annealed though. And only FL size when it gets hard to close the bolt (otherwise I bump size with Forster die).
My observation is merely that I have a load that has shot well in many different rifles under all different conditions.
 
#15
Re: First OCW results help

I decided to go with 45gr and adjust my seating depth to tighten up the groups.

Shot 200yrds, 3 shots per group, round robin style. Depths were (2.79, 2.80, 2.81). I'm pretty happy with my 2.79 results.

7544449296_0532270488_b.jpg
 
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