Rebarreling woes, 358 Hoosier, Savage 11

[cptmclark]

Last year I had a Savage 11 rebarreled by AJ Brown, with a Shilen .358 barrel in 358 Hoosier. After some growing pains with the dies and one bad lot of primers I found it to be quite accurate. However it threw its first shot 1.5 inches low before shooting a very tight three inch group every time. Shots 4 and 5 walked upwards way out of the group. The gunsmith offered to look for the problem and Shilen also said they wanted the barrel back as they looked at the targets and said for sure it's group walking and probably needs to have the heat treating re-done as there looked to be some stress remaining in the steel.

Shilen did their work but did not have chamber gauges so sent the whole thing back to me to install the barrel, which I did. Without head space gauges I installed the barrel as follows, which the Shilen rep suggested.

I snugged the barrel onto a spent case fired in the same chamber. Then backed the barrel off 1/8 turn and tightened it down. I noticed the aft trigger guard wood screw (fastens into plastic only and bears no load) is stripped. I packed the hole and snugged it down thinking it's of no consequence. I torqued the action screws to 35# and the scope mount screws to 15 pounds, reinstalling the same scope. Scope has given good service on two rifles before.

Off to the range with the same three best load from before the barrel work.
Sadly, the groups were much worse than before.

Some serious vertical stringing, best load now almost 2MOA and the others almost 4. This time the group is random, not walking up with each shot like before. But only vertical. Good bench set up.

Finally, the question.
Could I have installed the barrel incorrectly? Slightly more or less headspace needed? It seems pretty simple to install in the stock as it just beds against two metal pillars. Stock is synthetic. I used channel locks and a leather strap to tighten the barrel nut as much as I reasonably could. It seems quite tight. Could it need more or less headspace to prevent this vertical stringing? The loads chamber easily and bullets and OAL measure the same to be .020 off the lands. Shoulder position might be a couple thousanths off? Could that cause such a difference? Factory loads are always a tad loose in chambers.

I'm down to about 20 bullets of the best accuacy ones, and Barnes says several more weeks before making more. Time is running out to send it back to the gunsmith or Shilen. Do I sound desperate? I've always been able to get rifles more accurate for 50 years, but this one has some new angle as I've never mounted a barrel before. The Savage looks pretty fool proof, but I'm not shy about learning I've messed up.

I'll replace the scope and try again, but doubt that is the issue.

Thank you for any and all wisdom about installing the barrel or any other likely culprit.

Humbly,

 

[Jimro]

I snugged the barrel onto a spent case fired in the same chamber. Then backed the barrel off 1/8 turn and tightened it down.

You just created more headspace than you need.

If you are handloading, resize a once fired brass in your full length sizing die. I like to fill the brass with epoxy resin so there is no chance of deforming when you use it to set headspace, but that's just me.

This is a savage, so tighten the action down to the barrel until it stop, with your full length resized case inside (extractor and ejector off the bolt head). Then tighten down your barrel nut. Tightening the barrel nut should pull the chamber a thousandths or so away from the bolt face, setting headspace to your full length reloading die.

Check your headspace by chambering the guage you made with paper shims between the bolt face and the case head. Once you can't turn the bolt handle down, measure the paper with a micrometer so you know for sure.

Secondly, do an OCW handloading workup for your rifle. With your headspace set to your die, you should be able to work up an MOA or better load. You may have to try different bullets until you find one your rifle likes.

Hope this helps.

Jim

 

[cptmclark]

Thank you Jim,

I'll try that. While that may improve my headspace, can slightly more headspace than needed cause the vertical stringing I'm experiencing?

Also, am I correct in thinking the stripped aft guard wood screw hole being buggered is of no consequence?

Then, about the cartridges I've loaded to fit the current chamber,:
After shortening headspace, can I simply recheck the distance to the lands and set the bullets that much deeper in the cases? Is .020 a good rule of thumb starting point for distance off the lands?

My most accurate bullet in this barrel out of three after much testing is an all copper bullet. Not the way I wanted it to turn out but there it is.

Thanks mucho. I'll have an opportunity to shoot it again tomorrow. If I change the scope AND the headspace I'll have two variables that might have fixed the vertical stringing. But it is far to the range and time is short.

Thanks again and keep the advice coming.

 

[Jimro]

Vertical stringing could be exacerbated by headspace issues. Generally it does not cause vertical stringing, but it can make any condition worse.

If you haven't pillar bedded the action screws and glass bedded the action, now is a good time to do that. If you have pillar bedded the action and free floated the barrel, it might be worth it to pressure bed the barrel. It isn't a preferred technique for a target rifle, but for a hunting rifle can generally get barrels to stay sub MOA for 3 to 5 shots.

Yes you can just seat the bullets that much deeper into the case to keep bullet jump consistent. As far as handloading goes there are two schools of thoughts, one is to find the optimal charge weight first then fine tune with bullet jump. The other involves finding optimal bullet jump then optimal charge weight. I recommend finding the optimal charge weight first, then adjusting for distance to the lands.

The all copper bullet will generally be longer than the same weight traditional bullets. I wouldn't call it the best bullet for your rifle until you fix whatever is causing the vertical stringing. Consider using the heaviest traditional bullet you can find and the lightest conventional bullet you can find, and loading them at starting loads once your rifle good to go.

Hope this helps.

 

[Unclenick]

Another thing to check is if the receiver face and barrel nut receiver side flat are perpendicular to their threads. If not, you can get heat walking from even properly stress-relieved steel.

I'm surprised that Shilen recommend that 1/8 turn. On the Savage that's about 0.006" of extra headspace by itself But it's not by itself. You will also have some chamber draw as tightening the barrel nut stretches the shoulder of the chamber away from the breech face. Could be another 0.002"-0.005", depending on how much elbow grease you applied. I'd have touched the fired case with the chamber shoulder and just tightened it like that first, then fired one test round to see if that case was any longer from head to shoulder than the one I'd set the chamber up with. If you don't own a comparator, just use a caliper and a spacer or fired case or other tubing that hits the shoulder about in the middle and compare to one of your original cases.

The example below is for .308 Winchester, and you don't have as much shoulder to work with, but if you pick the right alternative that slips over the neck OK, (maybe a 10 mm pistol case would be deep enough to work) you are good to go.

 

[Dufus]

Might have ruined the scope if you tightened it to 15 lbs (ft-lbs?)

A good scope should be tightened to maybe 23 to 45 inch-pounds.

I have seen a few ruined by over tightening the screws.