6.5CM - 147 ELD-M & 41.5 H4350 - Too Hot?

[MMH]

I am loading 6.5CM - 147 ELD-M & 41.5 H4350 in Alpha SRP brass. Average velocity is 2784 FPS. Shooting out of a MPA PMRII w/ a ARC Coup De Grace action & a MPA 26" 1:8 barrel. About every tenth shot the bolt lift is tight (nothing too crazy) and I see minor ejector marks. Primer looks OK.

I did not do much load development on this just settled on something that had a low SD on velocity. Don't want to punish my barrel or brass & I'm not shooting past 1200 yards so dropping a little velocity should not hurt me. Should I find a lower velocity node?

 

[acourvil]

A 147 at 2784 in a 6.5 Creed is definitely on the hot side. 41.5 is at the top of the reloading charts, and IIRC Alpha brass has a bit less volume, so I think your pressure is up there. It wouldn’t hurt to step it down a bit, especially if you may be shooting at hotter temps.

 

[Supersubes]

Yes, you're too hot. Just load 40.5gr and be done with it.

 

[MMH]

Yes, you're too hot. Just load 40.5gr and be done with it.

Sounds like a plan. I have about 130 rounds still loaded that I will shoot off and will start loading at 40.5 gr. Hodgdon lists max charge for H4350 & 147 gr. bullet as 41.8 and their data indicates 2680 FPS at that load w/ a 24" barrel so I clearly must have more pressure to get 2784. Also, a lot of people loading at 41.5. I had good results at 41.5 and settled in there. & thought that I had decent pressures.

 

[918v]

Sounds like a plan. I have about 130 rounds still loaded that I will shoot off and will start loading at 40.5 gr. Hodgdon lists max charge for H4350 & 147 gr. bullet as 41.8 and their data indicates 2680 FPS at that load w/ a 24" barrel so I clearly must have more pressure to get 2784. Also, a lot of people loading at 41.5. I had good results at 41.5 and settled in there. & thought that I had decent pressures.

That’s cuz they are using Hornady brass which is a lot lighter than Alpha and has more internal capacity.

 

[Rodney65]

That’s cuz they are using Hornady brass which is a lot lighter than Alpha and has more internal capacity.

I have a lot of Hornady brass and I am using 42.1gr H4350 with 147s and am still about 25fps slower than my Federal small and large primer brass loaded with 41.5gr. Never a pressure sign with either though even in the summer, at least that I can notice.

I am using 20" Tikka barrels so my speeds are slow already.

 

[Thump_rrr]

41.2gr in Lapua brass is my go to with 2 different rifles and 3 different bullets.
140 Berger Hybrid Target, 139 Lapua Scenar, and 147 Hornady ELD-M.

 

[matt33]

I just started using a lot of h4350, although I have used it in the past. In the past 41.5 grains of h4350 with Hornady 140 ELD-M's from several years ago would give me around 2,720 FPS from a 24 inch accuracy international in 6.5 CM.

In a newer lot of h4350 that I recently loaded, the same 41.5 grains gave me well over 2,800 FPS.

I'm not sure if the newer lots are actually significantly hotter, but they seem to be for me. I dropped down to 40.5 grains with a 140 Hornady eld-m, it gave great accuracy and about 2,750 FPS with really good ES and SD.

 

[supercorndogs]

I just started using a lot of h4350, although I have used it in the past. In the past 41.5 grains of h4350 with Hornady 140 ELD-M's from several years ago would give me around 2,720 FPS from a 24 inch accuracy international in 6.5 CM.

In a newer lot of h4350 that I recently loaded, the same 41.5 grains gave me well over 2,800 FPS.

I'm not sure if the newer lots are actually significantly hotter, but they seem to be for me. I dropped down to 40.5 grains with a 140 Hornady eld-m, it gave great accuracy and about 2,750 FPS with really good ES and SD.

Same lot of brass cases?

Does this thread represent a load development of backing off .3g from book max and seeing what happens?

 

[acourvil]

I just started using a lot of h4350, although I have used it in the past. In the past 41.5 grains of h4350 with Hornady 140 ELD-M's from several years ago would give me around 2,720 FPS from a 24 inch accuracy international in 6.5 CM.

In a newer lot of h4350 that I recently loaded, the same 41.5 grains gave me well over 2,800 FPS.

I'm not sure if the newer lots are actually significantly hotter, but they seem to be for me. I dropped down to 40.5 grains with a 140 Hornady eld-m, it gave great accuracy and about 2,750 FPS with really good ES and SD.

Not sure if you measure it, but how much moisture is in the powder will affect how hot it shoots. I try to keep my powder between 45-50% humidity.

 

[matt33]

Not sure if you measure it, but how much moisture is in the powder will affect how hot it shoots. I try to keep my powder between 45-50% humidity.

This may have been part of the issue. I do store my powder in a finished basement, but I keep the dehumidifier running in my reloading area. Generally at or just below 50% humidity

It's likely that the older stuff I loaded years ago was loaded before I started using dehumidifier