6.5 PRC Barrel Length 24"vs 26" Velocity

[new2mud]

Sorry, wrong barrel length. I thought it was appropriate to just post the 26" here as that is the original point for this thread in the first place. Shows the "theoretical" difference anyway.

View attachment 195493

JPNDAVE: am I reading this correctly that for Hornady brass, max H1000 charge for 147 ELD-M is 63.1 grains? (!!)

What I have experienced with my barrel (and others seem to corroborate) is that 57.5 gr H1000 is netting me 3018 FPS from a 25" barrel, which is much lower than the 61.9 shown above. I know I don't have a fast barrel, as it shoots factory 147 around 2900.

What am I missing here?

 

[jpndave]

JPNDAVE: am I reading this correctly that for Hornady brass, max H1000 charge for 147 ELD-M is 63.1 grains? (!!)

What I have experienced with my barrel (and others seem to corroborate) is that 57.5 gr H1000 is netting me 3018 FPS from a 25" barrel, which is much lower than the 61.9 shown above. I know I don't have a fast barrel, as it shoots factory 147 around 2900.

What am I missing here?

I would watch those speeds and not push it up much further. Something has to be increasing the pressure in your rifle to get those speeds. If it isn't tracking with what is shown then don't keep pushing.

QuickLOAD isn't a guaranteed prediction of velocity and pressure. It can only be as accurate as what gets put in, conditions, etc. It's just another tool. If your speeds and charges are close to what it shows then pressure is likely close. If it's off like you are saying there can be a number of reasons. Chamber/brass/throat are different and higher pressure, powder batch more heat, hotter primers, lots of things can change. I haven't done a ton of work since I got the program but the rifle I am working with right now tracks pretty consistent to what it predicts. As you get more advanced with the program it can be adjusted to match your particular load. Any of these charts that are posted need to be started low and worked up. Even the published load data can vary just as much. Without knowing exactly what is different it's hard to guess why your combo is so much different.

Always start low and work up. Maybe I should change the steps on those runs to show what lower charges and pressures would yield speed wise with bigger steps.

 

[foul bore]

JPNDAVE: am I reading this correctly that for Hornady brass, max H1000 charge for 147 ELD-M is 63.1 grains? (!!)

What I have experienced with my barrel (and others seem to corroborate) is that 57.5 gr H1000 is netting me 3018 FPS from a 25" barrel, which is much lower than the 61.9 shown above. I know I don't have a fast barrel, as it shoots factory 147 around 2900.

What am I missing here?

I totally agree, mine is very much the same, my info states 63 gr way past max load?

 

[highdrum]

I totally agree, mine is very much the same, my info states 63 gr way past max load?

This is Bergers suggestions for the 156. Wish Hornady would produce some this info free of charge. They have the old stand by powders but not much of the new stuff. I know guys are getting faster speeds thanisted here, but in adg brass which has slightly less capacity and much harder case heads.

 

[jpndave]

My understanding is Berger is using QuickLOAD for much of their data. Could be wrong but I remember seeing that somewhere. They are probably staying a little bit further down on the pressure chart. Maybe I'll try throwing one of those lines in and see what comes out...

I agree on giving out load data without holding it hostage to buy a manual that is just going to be outdated. You are going to buy their bullets at the least and likely brass or ammo to start with too.

 

[new2mud]

This is Bergers suggestions for the 156. Wish Hornady would produce some this info free of charge. They have the old stand by powders but not much of the new stuff. I know guys are getting faster speeds thanisted here, but in adg brass which has slightly less capacity and much harder case heads. View attachment 195767

Thanks for sharing this data.

Again, a warning for others to proceed with caution: I hit notable pressure at 59.9gr N565 at 87 degrees F. Was launching the 156 EOL at 3065 FPS (!).

At 59.7, was getting 3034 FPS, nearly 100 FPS faster than Berger's data.

 

[new2mud]

JPNDAVE: how well does QL corroborate Berger's data on N565 and H1000 in Hornady Brass?

 

[jpndave]

This is Bergers suggestions for the 156. Wish Hornady would produce some this info free of charge. They have the old stand by powders but not much of the new stuff. I know guys are getting faster speeds thanisted here, but in adg brass which has slightly less capacity and much harder case heads. View attachment 195767

JPNDAVE: how well does QL corroborate Berger's data on N565 and H1000 in Hornady Brass?

Sorry, life has been getting in the way.

With 6.5 PRC COAL 2.955" 156gr Berger 26" BBL it shows the following (mag primers could easily make the difference):
RE33 50.5gr at 2632fps & 67.1gr at 2970fps
RE26 52.0gr at 2646fps & 57.8gr at 2911fps
Retumbo 57.0gr at 2658fps & 63.3gr at 2948fps
H1000 54.5gr at 2611fps & 60.4gr at 2898fps
VVN565 53.5gr at 2597fps & 59.7gr at 2894fps

All of these are showing less than max pressure with that input.

 

[new2mud]

Sorry, life has been getting in the way.

With 6.5 PRC COAL 2.955" 156gr Berger 26" BBL it shows the following (mag primers could easily make the difference):
RE33 50.5gr at 2632fps & 67.1gr at 2970fps
RE26 52.0gr at 2646fps & 57.8gr at 2911fps
Retumbo 57.0gr at 2658fps & 63.3gr at 2948fps
H1000 54.5gr at 2611fps & 60.4gr at 2898fps
VVN565 53.5gr at 2597fps & 59.7gr at 2894fps

All of these are showing less than max pressure with that input.

Thanks for this. The upper end charge weights for H1000 and V565 corroborate where I've been hitting pressure, although I'm getting much higher velocities. I suppose I should just shut up and be grateful--but I don't think I'd be alone in seeing 3050+ fps at the upper end.

 

[jpndave]

Thanks for this. The upper end charge weights for H1000 and V565 corroborate where I've been hitting pressure, although I'm getting much higher velocities. I suppose I should just shut up and be grateful--but I don't think I'd be alone in seeing 3050+ fps at the upper end.

Those higher speeds are likely pushing more pressure. The data at those speeds I posted using the charge weights from Berger were all well below max pressure. With conditions more or less "normal" higher speeds = higher pressure. The fact that you are getting pressure signs and speeds with lower charges means pressure earlier. Maybe smaller chamber? Lower capacity thicker brass (ADG?), etc.

 

[new2mud]

Those higher speeds are likely pushing more pressure. The data at those speeds I posted using the charge weights from Berger were all well below max pressure. With conditions more or less "normal" higher speeds = higher pressure. The fact that you are getting pressure signs and speeds with lower charges means pressure earlier. Maybe smaller chamber? Lower capacity thicker brass (ADG?), etc.

0.188" freebore, using Hornady brass. I wasn't comfortable with what I was seeing at those higher velocities so I have backed off.

 

[Sundby]

Go 24".

 

[VLD Pilot]

Guys quoting speeds out of a Creedmoor that meet or beat a PRC are either over pressure or comparing a unicorn powder to a run of the mill slower powder. All things equal with correct powders for each the PRC will run ~200fps faster.

Just for kicks I did just that on QuickLOAD. Your ABLR 142 will run ~2950 out of a 24" Creedmoor and ~3000 out of a 26" with RL26 (unicorn powder in the Creedmoor). The PRC will run ~3150 out of a 24" and ~3200 out of a 26" with VV570 (unicorn powder in the PRC). Any individual variances from that from chambering, fast vs slow barrels, etc. could just as easily apply to one over the other. Those projections are at near max pressure on both but no over.

I have a 6.5 Creedmoor that I love. I hate to admit it but ended up with one after a few experiences shooting and carrying friends rifles. They just work. That is in a Kimber lightweight hunting rifle. If the weight or loss of a round or two in the mag box aren't an issue I'd do the PRC. If I wasn't building a 300 PRC for heavier stuff, I'd probably do the 6.5 PRC over the Creedmoor.

If it helps, I'd be happy to do a few runs in QuickLOAD for you.

Dave

I'm in the same camp. It's kinda like big foot, some say it exists but show me big foot. My buddy has a 6.5 CM and told me it would out shoot my .260. Out perform he meant as in faster velocities. His is a 26" barrel and my .260 has a 25". His managed 2830 with 142 SMKs mine managed 2890 with same powder. We were running the same powder but I could manage more due to more case capacity. His comment was he's had almost 3000 fps with that same load. 170 fps isn't real close but everyone's "close" is different. I've never got even close to 3K but never ran RL26 thru it. Bottom line, his didn't out run my .260. No way any 6.5 CM is even in the same world as the 6.5 PRC

 

[CMP70306]

Did some testing with the new 153.5 Berger's, went from 56gr to 57.5gr H1000 before I started getting ejector marks.

56 - 2834 fps es-13. sd-6.3
56.3 - 2847 fps es-19. sd-8
56.6 - 2844 fps es-24. sd-10 - 0.30 MOA
56.9 - 2878 fps es-34. sd-15.5
57.2 - 2878 fps es-17. sd-7.4 - 0.48 MOA
57.5 - 2916 fps es-29. sd-14.5

57.5 was my stopping point as it was the charge that got me just under 2980 fps with the 147gr ELD-M and it gave me ejector marks with the 153.5s. Barrel is a 24" Proof CF Pre-fit, COAL was 2.95 and I was using CCI 200 primers.

I got some RL-26 and learned that with the Berger's I can seat them to 3.04" which is long enough to alleviate the feeding issues I had with the 147gr ELD-M in my LA AICS mags so that will be my next test next week.