7mm-08 OAL / seating depth / excessive throat

ndallyn

ndallyn

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Last year I picked up a savage 14 american in 7mm-08. This thing seems to have an excessively long throat. I've spent a lot of time trying to get this thing to shoot I've tried: 120 gr. sierra spitzers, 139 gr. hornady sst, 130 gr. speer hot cor, 140 gr. barnes TSX, and could never get it to shoot better than 1.250" at 100. Also, if I seated to or under magazine length (listed max OAL) I couldn't get anywhere near the lands.

Last week I picked up some 162 gr. Amax's (a buddy told me to get some long heavy bullets, forget the max OAL, and load it like a single shot) and was able to get some good 0.750" groups with IMR 4895, and 4064 (also tried H414, and Varget). However, my OAL length of the loaded rounds was 2.955" which was 0.155" longer than the listed max OAL (seating to 0.015" off the lands). The rounds will still feed properly from the magazine with very little room to spare. I've heard that you have to seat the 7mm bullets long, but this seems pretty excessive.

Has anyone else had similar issues? I'm happy now that I know that the rifle likes the long heavy bullets and I can get it to shoot like I want. I'm a little disappointed though that I can't really take advantage of some of the lighter 110-120 gr bullets (run out of case neck before I can get anywere near the lands). Are there any potential issues with seating long like that?

Nathan
 
Can can modify the mag so that it can accept an OAL of 3.000", and is the action long enough to cycle at that OAL? 3.000" is too long for most short actions.

If not, aside from single feed, you can try running bullets with a Round Nose.
 
Ganderite said:
It shoots 0.75" and is short enough to fit the mag.

And you think there is a problem????!!!!
Click to expand...

No, not a huge problem. Just want to make sure that seating out that long isn't going to cause me any issues (only been reloading for a couple years - this is the first gun I've had issues with). To be clear, it shot 0.750 with a couple loads last time I had it out (seating way over max OAL). The real disappointment for me is that it won't shoot the lighter and therefore shorter bullets nearly as well as a longer heavier bullets because I can't seat long enough with them.

I think I lucked out more than anything with the mag length - the loaded rounds will just barely squeak in.

The chamber dimension isn't the issue (I used a mic and height guage to check my fired cases), the length of the throat is.
 
The distance to lands on my Sako 7mm-08 is .060" longer than the max COAL of 2.80. I've set them about .015" off the lands and they seem to work fine in the mag...
 
I'm seating the 162gr AMAX to 2.950 in my savage 11 with a Shilen tube... I can JUST fit them in the mag and I'm .010 from the lands... With them out that far I can squeeze 47gr of H4350 in the case with maybe a touch more if I need to (still working on the load).
 
The Sierra Games Kings if this is a hunting round or the Sierra Match King if it will be for target.I too have had a 7-08 that was acting like this until a found a powder it liked and bullets, other combinations have worked but some are better than others.

The Sierra "king" bullets seem to be the least sensitive to seating depth.

For powder I went to H4350 for my accuracy loads, with this powder my overall accuracy/consistency during load development was much better as well as when I used SMK's.

As for OAL pick one that fits your magazine and stick with it, play with your powder charge and I bet you will find something that works.

For hunting I am using 150 SC II's and W760, with nice results.
 
If you properly prepare your cases, use a good bullet seating die and use tangent ogive bullets (most Sierra and Nosler bullets), a bullet can jump up to 0.120" with no accuracy issues.
I'm not talking about benchrest accuracy but honest 0.50-0.75 MOA 5 shot groups with a well bedded rifle.

Again the keys to accuracy with with a long throat:
  • use tangent ogive bullets (not seating depth sensitive)
  • use a good bullet seating die
  • prepare cases properly (this might mean a good sizing dies, a good case trimmer and an outside neck turner)

I've had to rebarrel a 243 Win rifle which still shoot around 0.75-1 MOA 5 shot groups with 0.180" jump with Sierra Blitz bullets!
I was regularly getting fliers that would transform a 0.5 MOA group into a 0.75 MOA group (or a0.75 group into a 1 MOA group) :(

Alex
 
That's a quite expensive .25" gain if you ask me.... I generally don't rebarrel unless the groups open up past useable, for its intended purpose that is.
 
Nothing unusual about a rifle showing a strong preference about what weight of bullet it likes. You should be pleased that you found something that works. That at least confirms the rifle is a good one.

The powders you have are well suited to the lighter bullets. For heavier hunting bullets you should try something in the 4350 to 4831 range. A heavier bullet is perfect for deer and moose.

If you want a lighter bullet to work, try different brands of bullets around 150 gr. with your powders. This is the fun of load development.
 
Ganderite said:
Nothing unusual about a rifle showing a strong preference about what weight of bullet it likes. You should be pleased that you found something that works. That at least confirms the rifle is a good one.

The powders you have are well suited to the lighter bullets. For heavier hunting bullets you should try something in the 4350 to 4831 range. A heavier bullet is perfect for deer and moose.

If you want a lighter bullet to work, try different brands of bullets around 150 gr. with your powders. This is the fun of load development.
Click to expand...

Trust me when I say that after almost a year of beating my head against the wall, and debating whether or not to rebarrel, I'm very pleased to have some success. I was going to get some 4350, but couldn't find any locally, so I picked up the H414 to try instead. As soon as I can get some, I'm going to try it out - and some H4895 instead of the IMR as well.

My .223 and .308 both were dialed in with one day at the range, all of my other guns were close to the same. This one has been a problem child..... so far I'm up to 6 different powders, 2 different primers, 2 different case brands, and 6 different bullets at 5 different weights. It's been a learning experience.

Thanks to everyone for their comments!

Nathan
 
Cleftwynd said:
That's a quite expensive .25" gain if you ask me.... I generally don't rebarrel unless the groups open up past useable, for its intended purpose that is.
Click to expand...

Consistency is the key to accuracy and I don't tolerate a barrel which produces flyers.
If a rifle is a 1 MOA rifle and never produces flyers, I'm okay with it.
If a rifle is a 0.5 MOA rifle but produces a flyer every 10 rounds, it's time for a new barrel.
Also if a rifle produced inconsistent accuracy and I can't "debug" it, I simply sell it.

Alex
 
Try it it works. ;) You might have bad vibes

Tuning Savage Actions Using Action Screw Torque Settings

http://bulletin.accurateshooter.com/2012/12/tuning-savage-actions-using-action-screw-torque-settings/

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