Shrink group size...some advice or help.

shooters said:

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Another question! Is it possible that what I'm shooting off of could cause this stringing? I'm shooting on an Atlas Bipod 6" and a solid bag at the rear. Gun is rock solid. Is the bipod causing an issue?

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I'm a 100% bipod/rear bag user, but if you're on a bench with a grippy surface, bipods can cause pretty nasty dispersion if the bipod "skips" on recoil because the feet don't slide smoothly. Probably worsens with recoil force, so might not be your problem with a tiny little gun like a 300 RUM...

I built a carbon 300rum and it loves 225 eldms with 96.6gr r33, f215, 3.845coal. Shot it to 1400yds and is very accurate. Berger 215s have always shot great also for me

Just got back from range.
The number of fingers represents the distance off lands.
2 being .020
3 being .030
4 fingers being .040

215 Bergers
Fed215M Primers
94g Reloader 33
.020 off lands.
Did exactly same thing as 208 ELDM's.
Not good

Next was .030 off lands. Group appears to have settled down...but still not that great.

Next was .040 off lands. Group opens back up but isn't so much of a vertical string but still horrendous.

Never have I had this issue with any rifle. Now what? Keep the .030 and try CCI250's, Retumbo... etc?
This is kind of getting irritating now.
Thanks everyone for all the help. I can't change anything other than the Primers, Powder, bullets right now. Can't do a different bushing.

Shooting .308 at 600 Yards. Use different bullets my rifle likes; Hornady A-Max, ELD, and Tipped Match Kings. Each had its own personality, and I load them how the rifle likes them. A lot of standard precision reloading case prep. Headspace I go for .001-.220 below SAMMI minimum. Seat at .010- .020 off the lands, and do a concentricity check and get them to ,001-.002 concentric. The A-Max likes a Seating depth at .010-.015, the ELD and TMKs like .020. The TMK is deeper into the throat than the Hornady's, but it the bullet shape that dictates that. I am shooting sub-MOA at 600yds. Typically cloverleafs at 100yds. The biggest factor determining accuracy with consistent reloads is the operator.

IMO, think it would be a good idea to verify the hardware. I would put the scope on another rifle and see how it does. Might be there is a loose screw on one of the bases or rail. Saw this just a few weeks ago on a guys 30-06, one of the screws on the front ring base had snapped. Maybe the action is shifting in the stock. I really don't think the stringing is a load issue.

Barrelnut said:

IMO, think it would be a good idea to verify the hardware. I would put the scope on another rifle and see how it does. Might be there is a loose screw on one of the bases or rail. Saw this just a few weeks ago on a guys 30-06, one of the screws on the front ring base had snapped. Maybe the action is shifting in the stock. I really don't think the stringing is a load issue.

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I removed everything before I went out last. NF Crossbolts are at 65 inch/lbs. Rings at 25inch/lbs. Stock screws are tight. Muzzle brake is tight. It's a brand new NF Atacr. Not saying there couldn't be an issue....but hard to believe the scope is it. Never know though.

and I know this is probably a little ridiculous, but I hand weigh the brass, each bullet, and each powder charge with two different scales just to verify and take out all variables. I also trim every piece of brass to the exact length. I've never had to do this with anything before, but like I said I'm just trying to take out anything that could be a variable. All once fired brass as well. Also using Redding Comp dies. Nothing cheap.

That's a very nice rifle. I would be unbelievably frustrated at this point.

shooters said:

I removed everything before I went out last. NF Crossbolts are at 65 inch/lbs. Rings at 25inch/lbs. Stock screws are tight. Muzzle brake is tight. It's a brand new NF Atacr. Not saying there couldn't be an issue....but hard to believe the scope is it. Never know though.

and I know this is probably a little ridiculous, but I hand weigh the brass, each bullet, and each powder charge with two different scales just to verify and take out all variables. I also trim every piece of brass to the exact length. I've never had to do this with anything before, but like I said I'm just trying to take out anything that could be a variable. All once fired brass as well. Also using Redding Comp dies. Nothing cheap.

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Shooters,
That is a light load of r33 imo. I don't know your batch or pressure signs but my node is usually from 98-100. What are you using for a front and rear rest?

Not bad. The 3 finger group is 0.83". I would adjust the powder charge and see if I can dial that in better.

Mram10us said:

Shooters,
That is a light load of r33 imo. I don't know your batch or pressure signs but my node is usually from 98-100. What are you using for a front and rear rest?

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I'm using an Atlas Bipod for the front and a SEB bag for the rear.
I haven't had a sticky bolt but at 97g of 33 with the 208, the primer definitely seemed to fill the pocket. It wasn't lipped or anything though.

Shooting of concrete bench or in the dirt?
I'd suggest doing load development with a good front rest and rear bag off a bench. Then use your bipod and whatever you use for a rear rest in the field (I use my rangefinder) to build your dope chart.

Mram10us said:

Shooting of concrete bench or in the dirt?
I'd suggest doing load development with a good front rest and rear bag off a bench. Then use your bipod and whatever you use for a rear rest in the field (I use my rangefinder) to build your dope chart.

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Concrete bench.

I'm heading out again and taking that 3/4" group and going.....

93g Reloader 33. Backed off 1 grain. Kept all the rest the same.
92g Reloader 33. Backed off 2 grains. Again, kept all the rear the same.

And gonna try...
89g Retumbo with same brass, primer, bullet and depth Just to see for sh*%s if the Retumbo makes a difference. Be back shorty.

shooters said:

Concrete bench...

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I'd try putting a piece of hefty card board under the bipod feet. As mentioned, if the bipod grips the bench too well, it can erratically skip/stutter backwards on recoil.

That consistent vertical stringing really makes me think it's a rifle/shooter problem that needs addressed before bothering to chase loads. I think you mentioned having some other load that shoots well. I'd confirm that's still the case before going further with load development.

Wish i had caught you. Would have suggested sneak in kitchen and take wife's good cutting board (the big one) and but it between the bench and bipod. Dont get caught, i did... not fun, but it did help.