6.5 x 47 issues

[Keithp]

Hi all

I have just shot a new rifle for the first time and i appear to have a problem with stabilising .

Its 6.5x47 , 1 in 8.5 twist 18" long . We shot it a 100 yards to zero with factory ammo in 108 and 123g and the rounds were hitting the target leaving clear imprints of the bullet hitting sideways !

We has another rifle which ad been made by the same guy with the same reamer shoot the same ammo with no issues . Everything seems ok with crown and bore so at the moment we are a little stumped as to where the issue is .

Any thoughts.

Keith

 

[Grimstod]

Muzzle vilocity? Stability is a combination of speed and barrel twist rate.

 

[Keithp]

Hi

That is something that I have been just talking about with someone else, then the curved ball to that thought is my other pal, used the ammo in a 14' barrel 6.5 x 47 rifle with no issues, so that takes me down the route that the bore is oversize in some way, losing both velocity and grip on the projectile (can't think of another term !) we are going to shoot it over a chronograph tomorrow night with factory and some of his home loads which are 95g v max, if these run slower or the same as his rifle with a 14'' barrel, it has to be the barrel.

 

[DukeDuke]

have you measured the barrel twist yourself?

 

[Keithp]

have you measured the barrel twist yourself?

Yes first thing we suspected, checked it yesterday and again just to be sure a few moments ago , also ran a very tight patch through it to see if there was any variance in resistance , a bit crude bit the only way i can do it and it felt fine , no guarantee of that but no noticeable tight or lose areas.

 

[jonbearman]

Have you tried to measure the bore itself?

 

[Keithp]

Have you tried to measure the bore itself?

I dont have the kit to measure it accurately so no, I have attempted to measure the dia across the peaks of the lands with a HSS Drill bit as a plug gauge and a 6.5 bit falls in there as has play !

 

[johnfred1965]

I dont have the kit to measure it accurately so no, I have attempted to measure the dia across the peaks of the lands with a HSS Drill bit as a plug gauge and a 6.5 bit falls in there as has play !

could you just drop a6.5 bullet in there for a gauge? how is the crown?

 

[jonbearman]

Wouldn't be weird if it were a 7mm barrel by accident.

 

[joshb]

^^^^^^^^^^ Yup. Sounds like you got a 7X47.

 

[Keithp]

It is strange indeed, i am going to try and get hold of some plug gauges today to get an accurate measure of the bore across the lands , i made a crude gauge up last nigh to measure the bore across the lands and its ok.

First thing we tried was a round as a check , as i do actually have a 2nd 7mm barrel.

I am starting to wonder if the short barrel is losing too much velocity to stabilise the factory ammo.

 

[msalm]

Is there a brake on it and you're getting baffle strikes??? The 108's and 123's should have absolutely no problem stabilizing in that barrel with an 8.5 twist....unless it is 7mm. Can you insert a bullet in the muzzle, does it slide in or stop ahead of the ogive. Place a bullet point first in the muzzle and spin it to scribe a line. Measure the diameter at the line and you'll have a fairly close measurement of your bore diameter (not groove diameter).

 

[yorketransport]

I doubt the short barrel is the cause. I've run a lot of 18-19" barrels in 6, 6.5 and 7mm without having stability issues when shooting relatively heavy for caliber bullets out of 8-9" twists.

Not saying that this is the issue you're having but I did have a similar issue once. Factory hunting rifle in 300 WSM shooting factory ammo. While zeroing the rifle the bullets were key holing at 100 yards. We were sighting in out in the woods and didn't notice that there was some grass along the flight path. Hitting a blade of grass was enough to send the 180gr bullet tumbling. It took me 30 minutes and another 10 shots to figure that out!

 

[CJ6]

I've shot 129-130 gr bullets as low as 1675 fps in a 8.5 twist XP (15" bbl) and they all went in straight.

 

[Keithp]

Right then !

We appear to be back on track , we dont have a clue what went on but all seems to be heading in the right direction

Went to see a pal plan was to use his known load from his 14'' 6.5 x 47 work up what it should be on quick load and shoot it over a chronograph to see what the results were our view equal or grater than his known velocity of 2950 with a 95 grain v max. so predicted load 3050 , actual 3054 ! quick load is scary accurate !

Best bit hole was round !

Tried a 108 g factory round same aiming point it bisected the first hole again round !

Zero it , and a rushed 3 round group of 1/2 inch again all round so not a clue whats going in , we did swop mods but this one is the same brand but a m/can rather than relax with a smaller bore .

I have no clue what went on and given today i am not going to start looking any further time to start working up a load for it properly .

So any one with 100g loads with ballistic tips ?

Thanks for the suggestions.

Keith

This is the rifle under discussion.

 

[Drop Port]

I would be willing to bet the other Mod is in need of repair, not the first time a baffle jig has been off.

 

[chalkeye]

Moderator issue? Not screwed on tight? Does the can have a clear bore?

 

[Keithp]

The original mod brand new and unused , was all my pal had available in the thread , i needed was for a 338 so more than ample clearance for the 6.5 . No strikes inside and had plenty of clearance was tight on as well.

Now to find a scope for it

Keith