Bullet switch caused pressure

[Jeffrey Van Zandt]

I've been shooting my 6.5 creed with 140 Berger elite hunters for a bit now and had some eldx 143s laying around. So I loaded up 20 of them with the same charge I've used for the Berger's. 39.8 grains of h4350 and set them to the same ogive. I got on target at 200 with one round, dialed up to 400 and had a heavy bolt lift but first round impact. Tried another and almost touched the last hole with no heavy bolt lift. Shot the other 20 at steel and had em all within about a 1.5" group on a 6 inch plate. But about 5 of them had heavy bolt lift and one the bolt didn't want to close. (Coulda got it but didn't want to force). All numbers on brass were the same as the Berger load and the ogive measurements were exactly the same. (Giving me a shorter COAL with the Hornady) any ideas what the issue was? Was thinking maybe neck turning might correct issue, or possibly bumping shoulders an extra thou? Primers looked great and no ejector marks at all.

changing any thing can do that go from reg LR primers to LRM can do it bullets can also along with powders ect righ along with temp cjanges in weather

 

[Dean2]

You are .7 of a grain off Hornady published max load for that bullet.. What velocity are you getting out of this load and the Berger load? I have not trouble seeing a load that close to max being over pressure in a given gun. I have hit max velocity MANY times well below the published max powder charge.

 

[rewiltshire]

I guess the lesson would be "never assume"

If you "assume" it will make an "*** out of You and Me"

 

[Howard Van Horn]

Also, if you use a Lee Factory crimp die (which I recommend doing) , the presure goes up. Use less powder than what your rifle's previous max load was.

 

[DJ Fergus]

The ELD-X has a longer bearing surface than the Berger Elite Hunters hybrids. You will need to back your charge off for the ELD-Xs,

Jacket is thicker on the 143 eldx too and I'm gonna guess the lead is is a touch harder. I cut into some of the original vlds and it was some of the softest cores I have saw. Which is what like.

 

[entoptics]

Not sure it is your issue but I have also found the ELDX/ELDM sit much closer to the lands in my 6.5 SAUM than any of the Bergers I have tried (140, 153.5 & 156). If you are close to the lands with the ELDX, that might also account for the odd case that was harder to close the bolt.

OP, did you measure the base to lands distance with the ELD, or just place the base to ogive the same as the Berger? Where the bullet contacts the lands isn't necessarily at 0.264 on the ogive. In fact, it's probably not, and will depend on the bullet shape and throat geometry. The lands are 0.256", so the bullet will likely touch somewhere between those diameters.

I had a brain fart the other day, and shot a batch of 7mm RM test loads 0.015" longer than the lands. I reran the tests a couple days later...

0.020" off the lands was ~40-60 fps slower than the ones that were hard jammed, using the exact same powder charges. Pressure showed up correspondingly sooner too, and I noticed the same issues with difficult chambering on a few of the loads, as I was obviously seating the bullet home with the bolt.

 

[bigngreen]

The 143 has more bearing surface but it's usually a little larger in diameter also, they have historically been a fat bullet by a few tenths and will pressure up.

 

[doggonner]

hornady bearing surface will cause pressure issues.had the same thing happen running 105 BT bergers and same load with 105 horny BTHP's I changed the ogive seat but the longer bearing surface caused a little extra bolt lift issue