.308 win lapua brass trimming??

[300ultramag]

Gents: i have been shooting a rem700 vs in .308 out to 1000yrds.i have been loading 155 scenars exclusivly with lapua brass filled with 45.5 grains of imr 4895,fed 210 primers loaded to 2.886" oal.my concern is i have to trim back my cases after each firing.they average 2.017" and i trim back to 2.010" as this is what my lead measured.i don't recall loading other calibers and having to trim each time.i also noticed my primer pockets are loosening after only 3 reloads!!i took care to size my brass just enough to put some resistance on the bolt when closing.i wouldn't think the .308 case would flow that much,is this normal

 

[fivering]

You didn't say whether you were using molyed bullets or not, but a quick and dirty run through Quick Load using your data shows pressures being WAY over what they should be.
Try seating the bullets out to engage the lands, this will maximize the initial case volume, lowering the pressure, and use a Stony Point Case Length gauge to only set your brass shoulder back 1/2 to 1 thousandth.
Switch to Varget, it's a little slower, and very commonly used.

 

[300ultramag]

fivering; i am using 155 lapua scenars [moly]i have a very long throat at 2.966" if i seat the bullets touching the lands i won't have enough bullet in the neck.i would only have .155" contacting in the neck,excluding the boattail. my primers are fairly flat but i have no hard bolt or ejector marks.this load only gets me 2800 fps out of the factory tube.

 

[MSwickard]

Not knowing you chamber dimensions, and how long the leade is, I would seat the bullets out as far as possible but make sure they have enough neck to keep them from moving. I suspect that the reason you are having to trim cases after each firing is do to the fact that the headspace is not correct. I feel you maybe over sizing the cases and bumping the shoulder too much.

I use Lapua 308 brass in my Hunter BR rifle chambered for a tight neck 308 Obermeyer. Once my cases have had full charges I barely have to trim the cases. If so it is just a slight squaring of the neck. To resize my cases I use a std FL RCBS 308 Win die. Works great with the lapua brass. In fact I put a smaller expanding button,.270) to hold the decapping pin and to keep from touching the neck. The die sizes to 0.329" and works great with my 0.333" chamber.

For your rifle, I would remove the firing pin from your bolt and take a sized case and place it in the chamber. Now see if the bolt,with out firing pin ) has any resistance closing on the case. I suspect it will fall shut. If it has no resistance the case shoulder is not making contact with the chamber shoulder.

You only want to size your cases so when using the procedure above that the bolt has some resistance when closing but is easy to close. You do not want the bolt to fall closed under its own weight.

Let us know what you find out.

Mike

 

[Bobjensen]

You didn't say whether you were using molyed bullets or not, but a quick and dirty run through Quick Load using your data shows pressures being WAY over what they should be.
Try seating the bullets out to engage the lands, this will maximize the initial case volume, lowering the pressure, and use a Stony Point Case Length gauge to only set your brass shoulder back 1/2 to 1 thousandth.
Switch to Varget, it's a little slower, and very commonly used.

 

[Bobjensen]

Fivering,

If indeed too much headspace is the problem you can check that quickly. Take an unsized case fired in the rifle, decap and reprime it and shoot it. The primer will be slightly above flush. Take a case you have resized and ready to load or pull the bullet on a round ready to fire and shoot that casing. the difference in primer protrusion is the headspace you have built into the ammo and it shouldn't be more than a thousanth more than the fired case. In my opinion an adjustable headspace guage is an absolute essential especially if you have more than one rifle in the same caliber. This enables you to adjust a full length die to the same headspace as the fired case from that rifle. Simply back the die out of the press slightly to acheive the right size. Case lube makes a difference too. Errratic lube will give erratic headspace.
The primer alone will continue to move the shoulder on a case. Pop several in a row and watch the primer protrusion grow!
Bob Jensen

 

[tripcrow]

That's pretty clever Bob. thanks