Better Precision Increasing Jump?

[General RE LEE]

Interesting results today in my new Bartlein chambered in 6.5 CM. 140 ELDMs jumped 0.030 with 41.5 grains H4350 were “meh”. Same load in 143 ELDX was sub MOA.

Has anyone gotten tighter groups increasing the jump? My brain tells me if it won’t shoot close to lands, it’s not going to get better jumping further.

 

[Truck24hr]

I've tried .005 to .080 off on several different rifles with no real change. I usually hang around .020

 

[Fireflyfishing]

Might not like the ELDM. Go with what works with ELDX.

 

[General RE LEE]

Might not like the ELDM. Go with what works with ELDX.

Yep

I’ve got 10 rounds left so I seated them to factory COAL of 2.80 which is 0.080 jump. Will see if that makes a difference. I like the 143 ELDX so no loss if the 140 ELDMs don’t work. I could mess with powder charges but I loathe load development.

 

[Robobiss]

I have never noticed a big change in precision shooting large enough groups, but that’s just me.

The only reason I am even trying to find the lands is so that I can seat the bullet as far out as possible so I can stuff more powder in it.

 

[General RE LEE]

I have never noticed a big change in precision shooting large enough groups, but that’s just me.

The only reason I am even trying to find the lands is so that I can seat the bullet as far out as possible so I can stuff more powder in it.

I’m thinking out loud, but seating deeper MAY result in better groups cause it changes the empty case volume between powder and the bullet base.

 

[waspocrew]

Maybe - always worth giving it a try. I usually seat at 0.020” off and try a few powder charges. If I can’t get it to shoot, I’ll try a different powder instead of multiple seating depths.

 

[farmermail]

Interesting results today in my new Bartlein chambered in 6.5 CM. 140 ELDMs jumped 0.030 with 41.5 grains H4350 were “meh”. Same load in 143 ELDX was sub MOA.

Has anyone gotten tighter groups increasing the jump? My brain tells me if it won’t shoot close to lands, it’s not going to get better jumping further.

Yes, I have gotten better results increasing distance to lands. I have a 6.5 PRC with a Mcgowan barrel, and increasing jump took it from 1.2 MOA to .33 MOA. That said, I also have rifles where it has made no difference.

 

[sanpedroranch]

Every rifle and load combination is unique. IMO certain bullet profiles are prone to not be impacted by jump i.e. not as sensitive. It’s one reason Berger sells the heck out of the hybrid profile. I was shooting eldms (secant ogive) quite a bit. after about 2 years i went back to the BTHP (tangent ogive) and across the board shooting better average group sizes. If you’re hung up on using a particular profile and don’t even want to worry about seating depth. Just load to mag length and figure out charge weight get a barrel tuner brake like the Harrells or Cortina.