Hornady 75 ELDM were 1/4", now shoot 1"+ ??

[DellaDog]

Defiance Deviant, Mullerworks 24” barrel in Manners T6A for the first 1800 -2000 rounds was a laser. Now, shoots 1” random groups at best with Hornady 75 ELD match. Checked all the obvious, barrel fouling (cleaned of all copper and carbon and inspected with borescope - no carbon ring). No significant erosion, still measure close to original seating depth, about .010 off the lands.

Initial OCW found two nodes with 4895, both sub ½” Tried reshooting an OCW and nothing groups better than an inch, regardless of seating depth.

But, Berger 70 VLDs and 85.5s group ¼ - ½”

Tried a couple different lots and I just can’t get the Hornady’s to group.

This is how they shot for the first 2K rounds.
What am I missing? Suggestions?

 

[Cascade Hemi]

Did the velocity and SD change? Same lot of all components then and now?

 

[clcustom1911]

Well, looks like your barrel got it's fill of the cheap shit and wants some top shelf bullets ???

 

[spife7980]

How is your neck condition? Are they annealed, are they getting sized a whole lot? Thinning? Springing back more?

 

[NFAJohn]

Tagged

 

[918v]

After 2000 rounds the condition of your leade deteriorated to the point where your Hornady bullets don’t shoot well. You could set the barrel back and rechamber, or shoot a different bullet.

 

[DellaDog]

Did the velocity and SD change? Same lot of all components then and now?

After settling in, barrel shot and still shoots the 75s at 3015, decent SDs before (under 10) and similar after.

How is your neck condition? Are they annealed, are they getting sized a whole lot? Thinning? Springing back more?

Using both RWS & Lapua brass, both initially and now, annealed with Aztec AMP. No cases with more than 3 firings.

I'd lean towards a prematurely burnt barrel as well except just this weekend I shot the 70 VLDs w/ 23 gr VV and the 85.5s w/ Varget, both at sub 1/2".

Really driving me batty as I've run 1/2 dozen OCWs from 23.2 to 24.4 w/ 4895 and they all are crap.
(Ran with multiple seating depths as well)

 

[DellaDog]

After 2000 rounds the condition of your leade deteriorated to the point where your Hornady bullets don’t shoot well. You could set the barrel back and rechamber, or shoot a different bullet.

Thanks.
I'm convinced it's the specific bullets with the worn barrel (no clue the reason) but will probably just shoot the 70s inside 600 and the 85.5s to 1000.

(And save the 2500 + ELDMs for the next barrel. Think I'll try Bartlein next.)

 

[NFAJohn]

Thanks.
I'm convinced it's the specific bullets with the worn barrel (no clue the reason) but will probably just shoot the 70s inside 600 and the 85.5s to 1000.

(And save the 2500 + ELDMs for the next barrel. Think I'll try Bartlein next.)

What round and velocity? Doing research on a high speed 224 and I havn't seen either mentioned.

 

[FishDr]

This goes against conventional thinking with Eld-m. I started with .020 jump, then My groups opened up and I chased many things. Reset seating depth to .005 off lands and groups went back to previous small knots. Might give it a try.

 

[supercorndogs]

Can you find a tight spot in the bore when running a patch down the barrel? If so scrub that part out with some JB paste.

 

[918v]

Another consideration is the annealing. Did your accuracy go away after you annealed the brass?

 

[DellaDog]

Another consideration is the annealing. Did your accuracy go away after you annealed the brass?

I thought about that too. So I tried virgin Lapua expanded .001 under (same as the RWS) and same results as once fired Lapua. The only thing I haven’t tried is the original (un annealed RWS), but I seriously doubt that would wreck such a great load. I’ll try anyway.

Once you get used to terrific 1/4” groups with the 75s that easily hit 2 MOA plates at 1000, its hard to accept anything less.

 

[memilanuk]

Tried a couple different lots and I just can’t get the Hornady’s to group.

If I were a betting man, I'd be guessing that you originally had a particularly good lot - or at least one your barrel liked. Now, not so much.

Feed it what it likes.... which sounds like it's the stuff in the yellow boxes

 

[702lineman]

I have had this exact scenario happen to me and also happen to a friend of mine.

I switch brass, powders, thought the barrel was toast and spun up a new one. Old barrel had 800 rounds on it. Guess what? Same shit happened. The gun straight hammered when I first built it. Bugholes left and right, had multiple hits at over 1000 yards, ect.

Come to find out it was the bullets. Got to measuring and there was .035 difference in bto on the bullets. My friend switched lots and his diameter was undersized badly.

I switched to 85.5 bergers and he switch to 80s and went back to bugholes. I would get your comparator out and do some measuring.

 

[supercorndogs]

Have done any BTO and weight measurements on the bullets? Seems unlikely but maybe you just a had a couple crappy boxes of bullets.

^^^^^^Beat me too it. LOL.