Lapua Primer Pocket Tension??

[sigma2chi]

I did the test and that's what got me settled on 42.4. It was definitely the best group with zero vertical spread.

I've loaded 20 rounds with 42.1 and will see if I can even get close to the accuracy that 42.4 was giving me.

I REALLY appreciate all the advice from everyone here.
Can anyone that has a Lapua loading manual tell me what the max powder charge for H4895 and a 175gr. .308 rd is??

You really should do an OCW test and find out where your rifle likes it. Start 1.5 grains lower than the load you've been using, and work up from there in 0.3 grain increments to your current load. Your targets should tell you where your rifle likes it.

Search OCW test on Google, you'll find it in the first hit

 

[finnaddict]

At a minimum of 5 rounds each for each different charge. 3 shots is not enough if you let one fly. Makes the other two worthless. Do Not load 20 of the same charge until you have competed the ocw and established what charge works best. That is a waste of components. All you will get from that is it either worked or was a waste of time.

http://optimalchargeweight.embarqspace.com/

http://optimalchargeweight.embarqspace.com/ocw-instructions/4529817134

 

[sigma2chi]

At a minimum of 5 rounds each for each different charge. 3 shots is not enough if you let one fly. Makes the other two worthless. Do Not load 20 of the same charge until you have competed the ocw and established what charge works best. That is a waste of components. All you will get from that is it either worked or was a waste of time.

http://optimalchargeweight.embarqspace.com/

http://optimalchargeweight.embarqspace.com/ocw-instructions/4529817134

That's the problem. This "hot" load was by far the best charge according to my last OCW test

 

[spclark]

Hodgdon lists the 175 Sierra HPBT with H4895 at from 40.0 grains (2489 fps, 39,100 CUP) to 42.7 grains (2,647 fps, 49,000 CUP) loaded to 2.800" OAL.

It's gospel that published vendor loads tend to be conservative but even with that in mind it's foolish & bad practice to assume what's safe in one rifle will be in another.

I don't have my Litz reference handy to see how Lapua's 175 (that's the bullet you want to use, right?) compares to the Sierra. Different bearing lengths will influence how pressure curves change between bullets & has been a useful guide when I've done load interpolations before BUT it's not a practice I can recommend to the unprepared.

 

[Panzer22]

42.5 H4895 is the 175 node in my rifle, but Varget works better, has more nodes, and less pressure for me. Try another powder. You may find more accuracy and less pressure issues, same or close or even more velocity.

Also, if your sizing is wrong you can create stress on your cases. All sorts of things add up. Be a little flexible, and you'll get it worked out. But still would like to know what barrel, chamber and how much you size, and what accuracy are you getting now?

 

[sigma2chi]

42.5 H4895 is the 175 node in my rifle, but Varget works better, has more nodes, and less pressure for me. Try another powder. You may find more accuracy and less pressure issues, same or close or even more velocity.

Also, if your sizing is wrong you can create stress on your cases. All sorts of things add up. Be a little flexible, and you'll get it worked out. But still would like to know what barrel, chamber and how much you size, and what accuracy are you getting now?

I don't have my exact numbers in front of me for my chamber. (At work) but it's a 26" Kreiger barrel on a BAT action that Gradous built for me. At the 42.4 grain load with H4895, seating to 2.0975 I'm getting between 1/8 to 1/4 MOA groups. And I'm using Berger 175gr OTM Tactical s

 

[Panzer22]

I really think you might get a better result with Varget.

Another option may be to change the seating depth. I am guessing your measurement is base to ogive? I have some 175 bergers loaded in Nosler cases that base to ogive measure 2.210, or COAL of 2.840.

Quick comparative math, based on my lot of 175 bergers being .63 from ogive to tip, your COAL is 2.7275, which is short. The bullet is deeper in the case, which will increase pressure. Try going out to 2.820 or so. A tenth difference can be a lot. The 175 Berger will take about any jump you give it. Fwiw, my Varget load at that length in a factory rem 5R barrel will shoot 1/3 min very consistently occasionally better. Bipod and bag prone. The fat chamber and Linda Lovelace throat probably allow me to run that charge with no issue as well. 2720fps 24 in barrel, 15feet away.

 

[Panzer22]

Just talked with a guy that has a henrikson species off the Gradous reamer, you might have to be that short. The twin is too short for box stock 175 GMM, and is designed to be throated to spec after chambering to customers bullet choice. Is it possible you didn't ask for throating to a specific bullet and oal?

 

[sigma2chi]

Just talked with a guy that has a henrikson species off the Gradous reamer, you might have to be that short. The twin is too short for box stock 175 GMM, and is designed to be throated to spec after chambering to customers bullet choice. Is it possible you didn't ask for throating to a specific bullet and oal?

I have my measurements at home but no I didn't ask Robert for a specific throat or bullet OAL to be built to

 

[Panzer22]

. Gradous builds a damn fine rifle, but only to what you tell him to. If you didn't specify, then im Pretty sure he ran the henrikson straight then, which would account for the short length. If that's the case, which evidence is leading me to believe, I would get it throated to run the 175 jumping .010 from .050 from your max mag length, for a little room to grow as it wears over the next 6000 rds. Or switch to a VLD type they will run fine in that chamber. Just a thought. Not a big deal at all if it is.
Do you have any factory 308 175 match? If it won't chamber or engraves the bullet heavily, then that will prove the theory based on what I know about the reamer.

 

[sigma2chi]

My chamber length is - 2.0370

My OAL measured from ogive is - 2.1225

 

[aj300mag]

My chamber length is - 2.0370

My OAL measured from ogive is - 2.1225

I had Dave Kiff grind me a reamer specifically for the Berger 175gr Long Range bullets. He set the freebore at .090", My loads that are at jam measure 2.280" to the ogive using a Stoney Point measuring tool.

You may need someone to run a throating reamer in your barrel and lengthen your freebore...

 

[XTR]

Two things here with custom chambers. I didn't realize you had one.

What is the neck? I had a tight necked 308 barrel that was reamed as a no turn for W-W at .339, no way to shoot Lapua or Lake City in that chamber safely w/o turning necks. (forgot one day and fired a couple of M80ball rounds in it. Great big over pressure signs.)

The other is what is the distance to the lands? If you are jammed it runs the pressure up really fast as you approach max.

 

[Tim Singleton]

Here's another thought
The next time you buy brass try the Lapua 308 Palma brass with the small primer pocket
Use any of the SR magnum primer you would like. See how long the pockets hold up with these

 

[XTR]

Here's another thought
The next time you buy brass try the Lapua 308 Palma brass with the small primer pocket
Use any of the SR magnum primer you would like. See how long the pockets hold up with these

I would not recommend that on a rifle that you plan to use in cold weather. I've talked to/read a number of comments from competition shooters who have had problems with consistency when it's cold.

 

[sigma2chi]

Here's what my primers look like. They didn't get any less flat when I shot the reduced load today.

 

[sigma2chi]

Here's my 100yd group from today with the hot load. 3-6 mom quarter value and medium mirage. Atlas bipod and a borderline too squishy rear bag.

 

[sigma2chi]

That group is turned sideways. Should be rotated 90 degree right

 

[Tim Singleton]

Here's another thought
The next time you buy brass try the Lapua 308 Palma brass with the small primer pocket
Use any of the SR magnum primer you would like. See how long the pockets hold up with these

I would not recommend that on a rifle that you plan to use in cold weather. I've talked to/read a number of comments from competition shooters who have had problems with consistency when it's cold.

This has not been my experience. I've had zero problems in cold weather.

 

[Panzer22]

The primers don't look bad really... Don't ever shoot an AR10 if those primers and cases look bad to you! Not the best indicator really. just a start and that can be just from the primer make up. a magnum primer wouldnt show as soon as a regular one.

I still stand by the throat needing cut some. No big deal at all. You won't loose anything and can certainly stand to gain something.