A little more history. This was a good load that turned out to be inconsistent. One bench group and two positions.
Consistency, or lack thereof
- Thread starter Josh Umsted
- Start date
Any time you get new brass, you've going to find variations in their head space. This is why its a good idea to fire form them to your particular chamber before you do any load development and you don't want to measure case volume until they're fired in you chamber to you have the proper case volume to your loading.
When Lapua brass comes boxed in the bulk, it's always a good idea to run a mandrel through them to be make sure the necks are round. Also, when they're trimmed, they're not chamfered and it's always best to seat bullets in a neck that's ben chamfered.
PS: for fire forming, it's ok to just load and shoot new cases. . . preferably with cheap bullets since you're not likely to get the best results until after you've fire formed them.
Forgot to include this Pareto chart from the little crow series that’s a nice summary of what he found impacts groups the most:
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What’s the total weight of your rig?
It sounds like you’re shooting a relatively lively recoiling cartridge in a light gun (which will move on you as you get fatigued and requires a fairly high level of recoil control 100% of the time to maintain NPA, and which only gets harder as the round count climbs) with a light barrel contour (that’s vastly more affected by higher temperatures, again, only getting worse as rounds add up). I’m not Sherlock Holmes, but maybe you should look into that…
If not that, I’d bet the solution to your lack of consistency is probably something simpler like: when’s the last time you checked your action screws or something? Sometimes what we see on target are symptoms of a different problem than we first assumed.
Or, feel free to continue trying to “Reloading Wizard” your way out of it by trying every brand of primers, doing some more ladder “testing” and trying every seating depth or whatever… that is popular around here after all.
I mean, there’s a lot of things to get tripped up on or that might have to get looked at, like: you said “REM700”… non-pinned lug? How’s the bedding in that Oryx? Or is it bedded? There’s a lot of things to scrutinize before turning to reloading-voodoo…
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I wish the shots on these targets were labeled in order fired. It looks to me like your rifle is trying to shoot two groups on each target. That's either you being inconsistent behind the gun, or something is shifting. Or maybe dragging.
I know you said your rifle was in an oryx chassis, but I had a 700 LTR that did the two group thing until I changed stocks. Put it in a bedded stock and that problem disappeared.
As to the dragging comment. I have a 700 in 300winmag that I chased my tail with off and on for years. Three barrels, three different smiths, four different stocks/chassis, 600 plus rounds of "load development" never found anything it would consistently shoot well. Not typical for a winmag. Some days it would hammer. Reload it and it would shotgun. Ended up being the firing pin assembly. Totally fixed it.
After much reading here (a few post from Chad Dixon of LRI were most helpful) and watching a pile of gunsmithing videos on YouTube about blueprinting the 700 bolt, I tore into mine and lo and behold, that was the source of all my problems. I've done it to all my 700's now and even the ones I thought shot good got better.
If your rifle has the J lock firing pin assembly in it like my LTR did, scrap it and order a pin assembly from GreTan.
For new Lapua brass, I chamfer the case mouth and run an expander mandrel/ball through the neck.
