HELP! 7X57 NOT STABILIZING

[chet]

Here's the scoop.... I just installed a new barrel on a push feed model 70. The barrel is stamped "federal firearms company, Pennsylvania usa". It is a 7mm mauser. Headspace is dead on and twist is 9.75".
It will not stabilize 140gr partitions! I double checked the twist, and i mic'd the bullets. I tried some 139 gr PPU. and they stabilized, but averaged about a 3" group. What would your next step be?

 

[chet]

Here's a photo of the key holing butthead!

 

[Guy Miner]

Wow - bore dia vs bullet dia?

And you're sure of the rifling twist?

Guy

 

[Anonymous]

Something is very wrong.

Any common 7x57 twist rate- most are between 1:9 and 1:10....should stabilize a 140gr bullet... a quick run through the calculator shows a twist as slow as 1:12.5" will stabilize that bullet.

I agree with Guy- I'd check to see if I had an undersized bullet or oversized bore.

Do you have any kind of pedigree on the barrel? Is it a take off or a new barrel?

 

[JD338]

I'd get a Hart barrel and start stacking shots.

JD338

 

[skidmark]

What fps ?

 

[Guy Miner]

I'd get a Hart barrel and start stacking shots.

JD338

Well, there is that option.

 

[chet]

I have no pedigree on the barrel. I bought it on gunbroker..... It appeared to be a brand new take off (yes, I likely bought someone elses problem).
.
I'm possitive of the twist.
.
I first fired PPU 139gr @ 70yds to zero the rifle, it shot fine. Then fired Federal premium 140pt to sight in for a hunt this weekend...... and the results are junk.
.
I measured the PT's, ... .284. I did not measure the PPU (all gone) and I have not measured the bore.
.
Does anybody know anything about "federal firearms company"?
.
I don't have a problem with junking the barrel (it was cheap) but it's so damn gorgeous!!!!

 

[chet]

It's purdyful!

 

[Guy Miner]

Well, if I'm reading your posts correctly - your best groups were only about 3" anyway...

I've never heard of "Federal Firearms Company" but I don't know every barrel maker out there.

Have you measured the bore of the barrel? It can be "slugged" with a piece of soft lead to determine the true diameter. Might not actually be .284"

I'd be inclined to do a little more checking - bore diameter - and then if no answer - time to turn it into a tomato stake...

Treat yourself to a Hart, Krieger, or other high quality barrel. You'll love it!

Guy

 

[chet]

you are exactly correct....
I'm just heart broken and need to whine about it :/
I'll try to slug it just for fun.....

 

[Anonymous]

you are exactly correct....
I'm just heart broken and need to whine about it :/
I'll try to slug it just for fun.....

If you really want to keep it- JES can re-bore it for a moderate fee.... maybe to the .338x57 that O'Connor wrote about... that'd be unusual....and classy.

 

[chet]

you are exactly correct....
I'm just heart broken and need to whine about it :/
I'll try to slug it just for fun.....

If you really want to keep it- JES can re-bore it for a moderate fee.... maybe to the .338x57 that O'Connor wrote about... that'd be unusual....and classy.

Or a Whelen!!!! I already have dies..... and lots of 06 brass!!! HEEYYYYY!!!!

 

[DON]

chet,
Now you're talking, re-barrel to a 35 whelen :mrgreen:

Don

 

[DrMike]

you are exactly correct....
I'm just heart broken and need to whine about it :/
I'll try to slug it just for fun.....

If you really want to keep it- JES can re-bore it for a moderate fee.... maybe to the .338x57 that O'Connor wrote about... that'd be unusual....and classy.

Or a Whelen!!!! I already have dies..... and lots of 06 brass!!! HEEYYYYY!!!!

Now you've done it, you drank the Kool-Aid. :mrgreen:

 

[chet]

I slugged the barrel... bore is .283"
I can't get a consistent measurement of lands, but I'd guess somewhere around .281" (seams a little weak)
I want to try at least one handload before I junk it.
I have on hand :
156gr oryx
154 gr hornady sp
160gr PT
120 gr vmax
Tell me what to try????

 

[elkeater2]

throat alignment comes to mind, have you ever done a chamber cast on anything? There is something weird here.
EE2

 

[chet]

no i have never cast a chamber. I can spin the barrel off easily if need be.....

 

[preacher]

I have never seen a standard 7x57 keyhole a 140, but I did have a nice Mod 70 FWT Classic in 7x57 that was a consistent 2"+ shooter! I had it rebarreled with a Douglas to 30-06 and shot my first cow elk with it. I have no idea what can be the culprit on your pretty rifle, but JES has a good reputation. If you are going to do the Whelen, heck, may as well do the 35 Whelen Ackley Improved and have a special rifle! ha

 

[Dwh7271]

Order a new barrel, pick a .473 head cartridge, and spin a new one on. Lots of good choices out there.