Request for Advice - inconsistent performance

[ttg7ya]

All,

Intermediate shooter here. Looking for some help in troubleshooting performance.

Seeing inconsistent performance with Norma 6.5 Creedmoor Golden Target OT match beyond 300 meters.

Rifle is Christensen Ridgeline 24 inch barrel and action. MDT Lightweight Hunter chassis. Chassis is torqued to spec.

Optic is NF NX8 2.5-20 FFP in mils. Optic is level. Tested with levels and plumb like. All screws torqued to spec with blue loctite.

Do not have a chronograph. Use a kestrel and Leica 2800 combination. Admit that my ballistic truing - only did once - may be the problem for transonic and subsonic shots past 880 meters, but I do not think that should not affect performance below 600. Please disagree if that is wrong.

Have gotten hits at 1,108 and 1,205 meters at gun club in Texas, so the barrel will shoot accurately. But during that session I noticed some inconsistent performance at ranges from 650 to 900. I attributed it the shooter.

Group dispersion when zeroing at 100 meters with this ammo is between .4 and .9 inches. Have shot about 9 3-shot groups to verify zero over three sessions.

Two weeks ago, in ideal desert conditions from bench rest after 5 rounds to verify zero, rifle drove tacks at 300 meters. Hit a golf ball and a 3 inch plate at 300.

Yesterday, from the prone with a 5-7 mph tailwind at 310 meters, I dialed in the hold called for by the kestrel and saw pretty wide dispersion over 10 shots. Everything was on the paper, but right of intended point of aim and high by 1-2 moa.

At 470 meters I dialed in the kestrel hold. First shot was very high. Re-ranged and got updated solution. All shots were on the 18” cardboard but were just above the 12” target. Spread across the entire target by about ten inches. Was aiming center diamond.

Would appreciate thoughts. My ideas:

(1) wind - seems unlikely to make that much impact with 6.5 CM at that range - but please tell me if that is wrong.

(2) inaccurate laser reading - Leica battery was dying and ultimately died during my last group.

(3) barrel heat - have read extensively about CA barrels suffering reduced accuracy after 10-15 rounds. If this is ultimately issue fine but want to rule it out before rebarreling with a proof.

(4) shooter. We were shooting from prone uphill with dust and shrubbery partially obscuring target. Hardly ideal for perfect form.

(5) scope correction error. I did not perform tall target test yesterday. Was shooting with a beginner and helping him zero a number of guns that required many adjustments. So by time we got to my rifle I wanted to get moving. Obvious mistake.

(6) ammo - obviously Norma is not Hornady or hand loads but I doubt this is the issue at these distances.

Would love some thoughts on developing a troubleshooting process. Ultimately, it may be the barrel, but I want to rule out all other errors first, particularly human ones (me).

Thanks in advance for any help!

 

[diverdon]

You're a long way down the rabbit hole for a who doesn't mention that he's tried Hornady ELD-X or ELD-M.

If you haven't you should.

 

[ttg7ya]

In other words, buy some better ammunition first that might perform better past 400 meters.

 

[canezach]

Your rifle might not like the 143 GTX. I've shot it out of my Desert Tech and it performed well. Out of my Seekins SP10, it's just meh

 

[ttg7ya]

Agree. TBH I have some skepticism that this is the barrel, but I am going to run 100 rounds of Hornady 147 Grain ELD Match through it and see how it does out to 1,000. If I see the same problems .... maybe rebarrel.

 

[todd]

I always look to number 4 first. Can you make your rifle shoot consistent sized groups at 100 yards, or does your group size vary quite a bit - one 5-shot group is .4" while the next one is 1.0", and the next one .6"? Obviously ammunition does have a part to play in this as well. I would try some Hornady 140 EDM, I had great success with it when I tried it.

 

[Dead Eye Dick]

Your rifle might not like the 143 GTX. I've shot it out of my Desert Tech and it performed well. Out of my Seekins SP10, it's just meh

I’ll second this. In a roundabout way. I own an older RPR which shoots the 6.5 ELD-X wonderfully. However, the .257 110 ELD-X’s barely can hit a barn at ten yards out of my very (for a hunting rifle) accurate Weatherby Vanguard. (Which loves Berger VLD Hunting bullets.)

Now there is some exaggeration here, but the 110’s struggle to put just three rounds inside 2 inches at 100 yards, the Berger’s in the same rifle put three shots under an inch (or better) as many times as you would like to try, all day long.