sr25/ar10/m5 load help 178 eldm over 4064 what velocities should i expect 20" barrel

[BigBlastin300win]

So i have been shooting 168 and 178's out of my m5 with great results. I am just wondering if i am running them way to slow. 20" barrel usually shooting suppressed. I just got a new batch of powder (4064) and virgin brass and i am running 50fps slower than my last batch. Just wondering how fast you guy are pushing 170's/178's out of a 20" gas gun. My last batch was running 2370 now i am running 2324. The temperature is also way different but i didnt expect 50fps.
I am about to reload out a new ladder with once fired brass and virgin just to see the difference but wondering if I can turn it up a little hotter? Some research i did on here said 41.5gr of 4064 was the old FGMM load (Dan Newberry)? I would like to get up to at least 2400-2500 but not sure hot hot you can run on a gasser. Pretty new to gas reloading so i went off the service rifle information in the reloading manual.
My old batch was 39.5gr of 4064 and did the same charge weight for the virgin brass last weekend.
With my 168's i run 42.9gr of 4064

Any insight would be greatly appreciated and helpful.

 

[OkieMike]

I had to look at my chronograph notes...

I was able to push 175 SMK's over 2500 out of my 18" .308 gasser using LC brass.

However, I was NOT using IMR 4064. I was using Shooter's World Match Rifle which is roughly equivalent to Accurate 2520. Charge weight was 42.2 to 42.6 range.

If I tried to push loads on that gun it was really hard on brass so I kept things low key. The above load cycled well and didn't flatten primers, or burr/smear the base.

I would have to dig through my notes to see if I ever shot 175's with 4064 in that gun. Off hand I would say No. I just never had luck with 4064 in that gun... I think it was due to some "port pressure" issues... Whatever it was my .308 gasser didn't like 4064.

Mike

 

[nn8734]

I'm running 175s at 2550 out of my SR25 (20" CL bbl) using LC LR brass, Rem 9-1/2 LRP, 42.5g Varget, seating them to .020 or so shy of mag length (KAC mags).

 

[Doom]

About 2500 fps is in the neighborhood of the velocity that you will likely get with most of the extruded powders. If you go to the spherical you might be able to push 2575 or so.

 

[BigBlastin300win]

I had to look at my chronograph notes...

I was able to push 175 SMK's over 2500 out of my 18" .308 gasser using LC brass.

However, I was NOT using IMR 4064. I was using Shooter's World Match Rifle which is roughly equivalent to Accurate 2520. Charge weight was 42.2 to 42.6 range.

If I tried to push loads on that gun it was really hard on brass so I kept things low key. The above load cycled well and didn't flatten primers, or burr/smear the base.

I would have to dig through my notes to see if I ever shot 175's with 4064 in that gun. Off hand I would say No. I just never had luck with 4064 in that gun... I think it was due to some "port pressure" issues... Whatever it was my .308 gasser didn't like 4064.

Mike

Thanks Mike really appreciate it! yeah it seems like the 4064 beats the crap out of the brass. Low or high charges in my gun leave a swipe or smear on the brass but i have been getting pretty decent groups. I just got 4064 because a year or two ago that was all that i could find. I am going to work up a ladder today and see if i can push the velocity just a little bit. 2500 out of an 18" is awesome! Thanks for the response.

 

[BigBlastin300win]

Also, nn8734 and Doom thank you for the replies. Sounds like i can push it just a little bit more. Forgot to mention i am running starline lrp brass fed 210m w/4064 and 178eldm's.