Pressure signs with .30 cal 178 ELD-m in .308 Win

[Mike4837]

Ok, I think I"m on the right track, but I want to see what others have to say. I'm trying to develop a load for the 178 ELD-m in my .308. Specs are as follows:

20" Bartlein 1:10" twist(Mile High AI barrel) w/ TBAC Ultra 7 .30 cal can
Federal Match Lg Rifle Primer
Lapua Brass(I tried it with Federal brass today too)
.30 cal 178 ELD-M Seated to 2.800" COAL
IMR 4166
.003" neck tension, full case resize.

So here's my problem, I'm at 40 grains of IMR 4166 and getting sticky bolt lift and some ejector swipes. My velocity is only around 2550 fps and factory FGMM 175's are at 2646fps.

I have the Hornady tool to measure the max seating length, I just can't remember the name right now. But when I used it the bullets stopped still pretty far in the case for some reason. SO I changed to the magic marker method and seated the bullet until I no longer got shiny spots from the lands and then bumped it back 0.020" from that. I ended up with 2.800". Obviously, I have a pressure problem.

My plan at this point is to pushed the bullets another .020" back and try again assuming that I'm barely touching or not touching the lands.

Have I lost my mind, or does this seem reasonable? I've loaded multiple different bullets for .308 and 6XC but Hornday bullets have never been awesome for me so I want to try to it great for once. The main difference for me this time has been the trouble finding the seating depth, so I'm leaning toward an error there.

 

[clcustom1911]

Perhaps you got a little faster burning lot of 4166. I used IMR 4064 in Lapua brass and 175 SMK's for years with great success. I suggest you try a little bit slower powder like Reloder 15 or Varget. Also, Ramshot TAC is a magical choice for 308 as well.

 

[918v]

The Hornady is a longer bullet and it takes up more room in the case and 4166 shows pressure early. You are expecting too much from this combo.

 

[Ryridesmotox]

Try 4064. Im getting 2712fps out of a 20 inch howa using the same bullets. Im using 45 gr of 4064 in jagemann brass, so my cases have more volume than lapua

 

[Huskydriver]

People use other powders besides varget or 4064 in a 308 with 175gr class bullets...?

 

[XLR308]

Just a suggestion but AR-COMP shoots lights out with every combo I have tried in 308win from 155cc and Scenars up to 190smk. If you want a little more velocity Varget is the shit but not as accurate in my testing YMMV.

 

[Doom]

For a comparison the 175 Sierra TMK with Winchester brass lists 41.5 grains and 2580 fps from a 24” barrel. With Lapua that woud drop to about 41.1 grains as max. From your description, it sounds like you have a tight chamber if you are .020 jump and at 2.800 COAL, but I’m not familiar with the ELD’s. If you are getting 2646 fps with FGMM 175 with a 20” barrel, that would tend to support that.

Like others I would recommend 4064, RL15 or Varget. There is so much data available for those powders and the issues are well documented.

Good luck.

 

[918v]

People use other powders besides varget or 4064 in a 308 with 175gr class bullets...?

48grs of PP2000MR

 

[Huskydriver]

48grs of PP2000MR

Sarcasm bud

 

[Mike4837]

This all good info guys! Thank you. I’ve used IMR 4166 for a while with 168’s, 175’s and a lot of 155’s, but never had these issues so I figured what difference does a design change and 3 grains make? Apparently a lot. I got 4166 back when people were stabbing their own mothers for varget and h4350. I couldn’t find varget anywhere. It was also being marketed as a really close substitute for varget. Apparently not so much in the heavies.

I do have 3 lbs of it on my shelf. I’ll give that a whirl. Just for giggles I might do my original plan and bump the bullets back .020” but I’m sure that won’t matter given this info.

 

[Doom]

48grs of PP2000MR

I had a load in that range with 178 Amax but the report was deafening and the muzzle flash was dazzling from a 20” barrel!

 

[918v]

And the recoil

 

[Feesh]

Just worked up a load in a friend’s gun.
178 ELD-X with 41.0 gr of Varget at 2.8” on a CCI primer in Hornady brass pushed over 2,600 FPS. In his particular rifle we saw pressure signs around 42.0 gr.