6.5 PRC

[Baffled321]

I wanted to get you guys’ input on what happened here:

I went out testing loads today. Not sure what all is relevant so here’s all the conditions:
Temp:95F
Elevation:5000ft
Powder:H1000
Bullet:156 Berger
COAL: 2.955
Primer: Winchester large rifle

At 57gr my bolt was just a bit sticky. Went up .5 gr at a time. Had to stop at 58.5 and had to use a rubber mallet to open the bolt. 58.6 would be 100% fill. How much of the problem was the heat? Where would you go from here? Thanks!

 

[ARlife4me]

High heat will always get you at top pressures. What are you wanting to know exactly? Info about max pressure or more about accuracy?

 

[Recon$$]

I run a RL 25 load that's pushing it. In high heat the gun doesn't like it. Sub 75 degrees is no problem.

 

[Baffled321]

My best grouping came at 58.5gr and I like the velocity from that load better too. Will the pressure (likely) go away at more normal temps say 80 and below?

 

[just_jon]

Using the data provided, QL shows 58.5 gr generates 69,244 psi at 70 degrees and 72,870 at 95 degrees. SAAMI max is 64,991 psi. It would appear that the high temps only exacerbated the overpressure situation. As for case fill, QL shows 58.5 at 110% at 2.955 COAL with a case H2O capacity of 65.9 grains. If you are at 100%, I suspect your case capacity is higher. If you can provide case capacity data, I can rerun to better answer the question as to whether this load will be overpressure at lower temps.

 

[ICMDEER]

Amazing coincidence. I'm shooting the same bullet, powder and almost the same overall length as you. I had the same problem with the sticky bolt. I ended up "backing off" on the H1000 (after trying am bunch of other powders). I'm now down to 54.6 grains of H1000 with the 156 grain Berger. Muzzle velocity is only 2840, but it shoots like darts. I shot at distance yesterday and had two shots at 833 yards that were almost touching. So I quit.

I guess what I am saying is don't be afraid to back off the powder. To me, the safety and accuracy are paramount. I can dial another MOA or two if the rifle functions well and the groups are tight.

Good question and best of luck.

 

[CaptDru]

How many loads do you have on the brass and what brand of brass are you using? Is your rifle custom or factory?

 

[Baffled321]

Using the data provided, QL shows 58.5 gr generates 69,244 psi at 70 degrees and 72,870 at 95 degrees. SAAMI max is 64,991 psi. It would appear that the high temps only exacerbated the overpressure situation. As for case fill, QL shows 58.5 at 110% at 2.955 COAL with a case H2O capacity of 65.9 grains. If you are at 100%, I suspect your case capacity is higher. If you can provide case capacity data, I can rerun to better answer the question as to whether this load will be overpressure at lower temps.

I’m only going by data provided by Berger. It shows a starting load of 54.5 gr and max of 60.4 listed as 103%. That’s where I figure 58.6 to be 100% (60.4/1.03). Thanks so much for the QL data!

 

[Baffled321]

How many loads do you have on the brass and what brand of brass are you using? Is your rifle custom or factory?

The rifle is factory. The brass is Nosler. Loaded just once or twice before

 

[Baffled321]

Amazing coincidence. I'm shooting the same bullet, powder and almost the same overall length as you. I had the same problem with the sticky bolt. I ended up "backing off" on the H1000 (after trying am bunch of other powders). I'm now down to 54.6 grains of H1000 with the 156 grain Berger. Muzzle velocity is only 2840, but it shoots like darts. I shot at distance yesterday and had two shots at 833 yards that were almost touching. So I quit.

I guess what I am saying is don't be afraid to back off the powder. To me, the safety and accuracy are paramount. I can dial another MOA or two if the rifle functions well and the groups are tight.

Good question and best of luck.

That’s good info! That’s good velocity too. Is that on a chrono? Berger data suggest 2644fps at 54.5

 

[waspocrew]

That load data from Berger has changed a few times - I've seen threads (wanna say it was on snipershide or Rokslide) where members posted emails from Berger and the data was definitely different.

Your rifle is telling you that you were too hot. Back it down and find another node.

 

[waspocrew]

Personally, I wouldn't want to be at the edge of pressure and then experience a swing in temp while hunting.

 

[ARlife4me]

I’m only going by data provided by Berger. It shows a starting load of 54.5 gr and max of 60.4 listed as 103%. That’s where I figure 58.6 to be 100% (60.4/1.03). Thanks so much for the QL data!

what isn't stated is case volume (case h2o) only and not as case fill %. also an unknow is lead/throat/jump as it will play a part on pressures. other(s) may argue about this, but I have a 243win that will agree as the throat is way short.

 

[FireFlyFishing]

I like loads that can shoot in all conditions. But that’s me.