K-31 Accuracy Tweaks

Ganderite

Ganderite

CGN Ultra frequent flyer
Rating - 99.7%
355   1   0
Location
Farm south of North Bay
I am shooting a K-31 in the ORA Sporting Rifle shoots. (Next one is Sept 17, BTW)

I have been doing some load development for it and my #4. The #4 now shoots around 1.5" at 100.

The K-31 is closer to 2.5" (with 175gr SMK). I have a 3-9 scope on it.

Before i do any more testing, is there anything I should know about the rifle set up?
 
Action screws and barrel bands.

Front action screw should be tight.
Tang action screw torque can be tuned for best accuracy by minor changes in tension. It should always be at least making contact , then tighten 1/16 to 1/8 turn until you find best accuracy.

Barrel bands:
Sling barrel band screw should always be loose enough that the spring detente does not bind. You should be able to push the detente in and it should spring back all the way to make contact with that band.

Front barrel band torque can also be tuned like the Tang action screw. Suggest greasing or waxing the contact points of the stock tip and front tip of hand guard to the barrel to decrease friction which binds barrel to stock causing rising shots as the barrel heats up.

There will likely be a rectangular metal shim between the action block and the cutout in the stock for it.
That shim is to compensate for the compression of the wood over the years.
It tunes the amount of upwards pressure exerted on the bottom of the barrel at the stock tip.
The action block acts like the pivot point on a swing and tang screw torques moves tang down, raising the barrel.

SchnittA.jpg
 
Last edited:
Ganderite said:
I am shooting a K-31 in the ORA Sporting Rifle shoots. (Next one is Sept 17, BTW)

I have been doing some load development for it and my #4. The #4 now shoots around 1.5" at 100.

The K-31 is closer to 2.5" (with 175gr SMK). I have a 3-9 scope on it.

Before i do any more testing, is there anything I should know about the rifle set up?
Click to expand...

Did you try with GP11 ammo?
 
diopter said:
Action screws and barrel bands.

Front action screw should be tight.
Tang action screw torque can be tuned for best accuracy by minor changes in tension. It should always be at least making contact , then tighten 1/16 to 1/8 turn until you find best accuracy.

Barrel bands:
Sling barrel band screw should always be loose enough that the spring detente does not bind. You should be able to push the detente in and it should spring back all the way to make contact with that band.

Front barrel band torque can also be tuned like the Tang action screw. Suggest greasing or waxing the contact points of the stock tip and front tip of hand guard to the barrel to decrease friction which binds barrel to stock causing rising shots as the barrel heats up.

There will likely be a rectangular metal shim between the action block and the cutout in the stock for it.
That shim is to compensate for the compression of the wood over the years.
It tunes the amount of upwards pressure exerted on the bottom of the barrel at the stock tip.
The action block acts like the pivot point on a swing and tang screw torques moves tang down, raising the barrel.
Click to expand...

Thanks form this. I will check tensions before shooting tomorrow.
 
I can't offer any advise on stock K31 setup but I did some load development for my K31 and got sub MOA groups out of Sierra 168 tipped match kings and 43.9 gr IMR4064. I put it in a custom target stock that was pillar bedded.

I was getting 1.5 at 100 with GP11 fairly easily in the original stock.
 
Just came back from range. First time k31 shooting and I only shoot less 50 round in my life with iron sight. I am getting about 2 inches group. 2.5 at most. I don't reload but I know deep bullet seating is the key. I was shooting gp11
 
BTW. Never remove wood from the stock tip to "free float" it. It destroys long range accuracy.

Only exception is if stock is warped, but you will have to rebuild the stock tip with sawdust and wood glue to ensure an even surface with upwards pressure.
First time to center the repair with the barrel and a second time to insure some upwards pressure
 
Last edited:
diopter said:
Action screws and barrel bands.

Front action screw should be tight.
Tang action screw torque can be tuned for best accuracy by minor changes in tension. It should always be at least making contact , then tighten 1/16 to 1/8 turn until you find best accuracy.

Barrel bands:
Sling barrel band screw should always be loose enough that the spring detente does not bind. You should be able to push the detente in and it should spring back all the way to make contact with that band.

Front barrel band torque can also be tuned like the Tang action screw. Suggest greasing or waxing the contact points of the stock tip and front tip of hand guard to the barrel to decrease friction which binds barrel to stock causing rising shots as the barrel heats up.

There will likely be a rectangular metal shim between the action block and the cutout in the stock for it.
That shim is to compensate for the compression of the wood over the years.
It tunes the amount of upwards pressure exerted on the bottom of the barrel at the stock tip.
The action block acts like the pivot point on a swing and tang screw torques moves tang down, raising the barrel.

SchnittA.jpg
Click to expand...

Awesome, thanks!
 
Another "BTW.

The Blue B in the drawing is where the Recoil shoulder on the K31 is, not the block at the Blue A

SchnittA.jpg
 
Last edited:
diopter said:
Another "BTW.

The Blue B in the drawing is where the Recoil shoulder on the K31 is, not the block at the Blue A

SchnittA.jpg
Click to expand...

To increase tip pressure, switch to a thinner A?

And maybe an old gun needs a shim at B?

I shot today and found a load for both my 155 gr Match bullet and a 147 gr milsurp FMJ. Both grouped about 1.75" at 100 off bags with a 9X scope.
 
Last edited:
I opened up the rifle. No shim at B, so I added a 4 thou shim, the thinnest I have.

Why is A not a recoil lug? it sure looks like one.

This rifle looks like a good candidate for glass bedding.

Will test this in a few days and report here.
 
Last edited:
Lots of wood wood in B area rear stock to absorb the recoil and no magazine cutout to weaken it.
Much more solid. Tang helps direct recoil into the end grain of the buttstock.
Likely why K31s have thicker grip area
Rear of A block as designed does not make full contact with the wood between it and the magazine cut.

Advise getting it to group around 1 moa before any glass bedding, which might lock you into the condition is is at that time.
Try waxing or greasing the stock tip barrel channel. Results might surprise you.

Were your action screws a bit loose? Many of my K31s get loose after 30-40 shots.
I always check the screws before starting and after 30-40 rounds.

Alliant RL17 works extremely well as a powder for this cartridge.
Best accuracy has been with RL17 with Berger bullets, 175gr. VLD #30412, 168gr. VLD #30410 and 155gr. VLD #30408, in that order.
50grs RL-17 with 175gr bullet.
Whether it's worth the cost is up to the shooter.
 
Last edited:
a guy at range told me if i have vertical string, that is because stock tip touching the barrel. I did have a little bit vertical stringing,(two 1.6x0.9 inch 4shots group), but i will shoot more to make sure that is the rifle not me.
 
Believe nothing until you try it yourself on a particular rifle.
Different rifles may/will have very different results.

Just experiment in a way so you can go back to original condition if results are failures.

I had to fixed 3 K31s that were issued to club members.
They gouged out the barrel channel and could barely hold the black at 300m. Sighting-in was impossible with that rotten accuracy.
Built up the stock tip again with wood glue and sawdust until pressure re-attained and could group again.

Try waxing you stock tip.
Also try different distances, not just 100yds.
 
Last edited:
You must log in or register to reply here.
Back
Top Bottom