Handloads so good they keyhole!

[sinister]

My load is Sierra 175gr Mk, LC brass once fired through my rifle only, 43gr of 4064, Federal match primers, neck sized, and bullet seated with a Forester Ultra seating die.

Whose neck size die are you using and what does it size your external neck dimension to? Are you trimming your cases to length?

[STAMarine]

After you find the powder and charge that your rifle likes then you can start playing with COL's. the target below has five groups with the seating depth changed 0.01 for each group. With bergers it really makes a difference. MK's more forgiving.

Attachment 34401

Hopefully I can find a good charge but I'm still aways from adjusting COL. That's why I started with the MK's instead of Bergers because I knew I'd need all the leeway I could get!

[STAMarine]

That barrel still has plenty of life left in it. The beauty of a .308.

Yes if you want to shoot long range you need to find your max. It will be considerably above what is in the book. You are going to have to try different powders too. I like varget and RE-15 but then I don't shoot long range with my .308. It is my hunting rifle and I shoot the berger 168 VLD. For example berger says my max is 42.5 gr varget Hogdon says my max is 46 gr I use 44 gr.

For your 175 gr 4064 hogdon says your max is 45.6 gr

Looks like I'll have to start all over again. Your statement about barrel life calmed me down a little bit. I sure don't want to have to do that yet.

[markm]

That's why I started with the MK's instead of Bergers because I knew I'd need all the leeway I could get!

MKs are ridiculously forgiving. Some of the psuedo match ammo makers get away with like .010" runout, crappy brass, and the rounds fired in long leade barrels with no magnificent problems like this. There's something big going on here.

[STAMarine]

Whose neck size die are you using and what does it size your external neck dimension to? Are you trimming your cases to length?

I'm using a Lee neck sizer. Outside dimenw is .338. I haven't done any trimming on my fire formed brass because length is still below max. Should I trim anyway?

[STAMarine]

MKs are ridiculously forgiving. Some of the psuedo match ammo makers get away with like .010" runout, crappy brass, and the rounds fired in long leade barrels with no magnificent problems like this. There's something big going on here.

This doesn't bode well for my efforts. Your posts are ones that I follow and the words "something big is going on here" isn't something one wants to hear.

[rcoodyar15]

I'm using a Lee neck sizer. Outside dimenw is .338. I haven't done any trimming on my fire formed brass because length is still below max. Should I trim anyway?

Had to get up at 2AM for a concrete pour this morning. Such is my life
I don't trim brass till it Is long. Short brass suxMon

I did think of something last night. Barrel has over 2000 rounds through it. Have you ever used a copper remover like Sweets or Montana extreme?

[rcoodyar15]

I'm using a Lee neck sizer. Outside dimenw is .338. I haven't done any trimming on my fire formed brass because length is still below max. Should I trim anyway?

Had to get up at 2AM for a concrete pour this morning. Such is my life

I don't trim brass till it Is long. Short brass sux

I did think of something last night. Barrel has over 2000 rounds through it. Have you ever used a copper remover like Sweets or Montana extreme?

Try some Hornady Amax 178. Some guns like different bullets. Mine likes the Amax.

I use the lee collet neck sizer with great success

[rcoodyar15]

This doesn't bode well for my efforts. Your posts are ones that I follow and the words "something big is going on here" isn't something one wants to hear.

I would not worry. It is something simple. Your shorter range groups are too good for something big to be going on.

[opsoff1]

First off, all the rumblings and musings about COL and trimming brass and copper in the bore is completely irrelevant. None of that is going to produce a destabilized round. Your load of 43.0 is a stout load - that isn't any sleeper. Your perceived recoil difference is a starting point though. FGMM isn't a hot load - so to have a 175 w/ that much 4064 behind it feel less tells me something is wrong in your powder tossing op.
A few questions:
1. How did you throw your charges? Hand weigh each? Uniflow or similar? Chargemaster?
2. Is the scale calibrated w/ known/verified check weights?
3. Powder...how old? Does it smell right (should have an ether type odor to it)
4. Is it a new can you just opened or is it something you have been using with other loads?
5. Measure the diameter of the bullets - they should be .3082 max. If they are under .308, i.e. .306 or .307 - thats a problem... Sierra has pretty good QC, but sometimes an odd batch gets by - rare - but it happens.

The rifle issues, and based on the fact that FGMM shoots fine should be the last of your concerns. 1/10, 1/11 or 1/12 will stabilize the 175. I shoot old long BT SMK180's out of a 1/12 Palma rifle and they fly very straight.
A 308 that is driven hard will give you faithful service past 6K - mild loads and no sustained shooting (read rapid fire stuff) may get you up to 8K or more. Everything here points to an ammunition issue.

I would first start by pulling the bullets on a few of the rounds that are giving you problems - measure the powder. From there I would load another 5 rds using the exact same components and procedures as you have been doing.
Shoot these at a range where they will be on paper consistently. (300 yds maybe?) then with known ammo of good quality (i.e. FGM 168's) - shoot another group at the same yardage with all the same settings & zeros. My guess is you are going to see a measurable difference in elevation. If your 175 hand load is way lower - and you have truly 43 gr of 4064 in there - thats a powder issue.

I'm with MarkM on this - something big going on here and I'm pretty sure it isn't the rifle.
Start with the basics and change one component at a time to isolate the problem.
Standing by to assist.