Powder Selection Assistance

[mtnrunner260]

Looking for options with a 18in 6.5 PRC with 8 twist.
Currently using 147 ELD-M with Retumbo.
Getting a fairly compressed load at 57 grs. Went up to 58.4 with no pressure signs. But really have to crunch powder during seating.
57.2 grs is giving 2630 via shooting chrony. 58.4 gave an error so unsure of velocity.
Know I wont have a barn burner but thinking I could get some more speed.
Just found a lb of 4831SSC
Been keeping an eye out for H1000 and RL26.
Are there others powders I should consider?
Does the powder selection change if going to a 125-130gr copper bullet?
Also been using Fed210 for primers.
Thanks

 

[MThuntr]

You may be able to squeeze a bit more in using a drop tube assuming you haven't hit signs of pressure. Those big kernels really needs some help. 4831 may be too fast for the 143

For 125-130 copper, I'd go with the 124 Hammers using RL26, Ramshot Mag, or mayber even H4831. Hammer Bullets Forum has user loading info. Not sure what kind of fps you'd get with an 18" barrel.

 

[A382DWDZQ]

Going off Quick Load, that seems pretty slow to be giving pressure signs. H1000 will be slower. If you want faster, RL33, N570. At any rate, QL is showing me 2,507 fps from that barrel config with Retumbo, and just under 45,000psi, so is this a new barrel, or is it seated deep?
Edit, also curious what the case brand/capacity might be.

 

[mtnrunner260]

Going off Quick Load, that seems pretty slow to be giving pressure signs. H1000 will be slower. If you want faster, RL33, N570. At any rate, QL is showing me 2,507 fps from that barrel config with Retumbo, and just under 45,000psi, so is this a new barrel, or is it seated deep?
Edit, also curious what the case brand/capacity might be.

I meant no pressure signs, what goes through my head and what ends up on the page...
Barrel is a new Proof.
Lapua cases.
Thanks!

 

[jzeblaz]

I haven't loaded for 6.5 PRC, but does some of the data have a LRM primer, like the CCI 250? There is some data on this here: https://www.shootingtimes.com/editorial/65-prc-load-data/459124

 

[wind gypsy]

IMR7828, RL23, RL26, H4831

 

[Flyjunky]

I’d throw N565 into the mix as well

 

[Mag_7s]

You may be able to squeeze a bit more in using a drop tube assuming you haven't hit signs of pressure. Those big kernels really needs some help. 4831 may be too fast for the 143

For 125-130 copper, I'd go with the 124 Hammers using RL26, Ramshot Mag, or mayber even H4831. Hammer Bullets Forum has user loading info. Not sure what kind of fps you'd get with an 18" barrel.

Another idea if you don't have a drop tube is vibrate the charged cases in a loading block next to to a vibratory case tumbler. Play around with the distance to case tumbler to see some gentle vibration of powder. Dont leave it un attended, as the block can walk away from ya and you'll have a huge mess.

 

[A382DWDZQ]

I meant no pressure signs, what goes through my head and what ends up on the page...
Barrel is a new Proof.
Lapua cases.
Thanks!

Ahhh! That makes a lot more sense...

 

[A382DWDZQ]

Powder selection will change a bit if going to lighter projectile, but if you pick something that is on the faster side of the options above, that will probably be fine for the lighter copper. RL26 looks like a great option for both, same with 7828ssc, N570, 565, 560, and Magnum. Retumbo drops way down the list.

 

[mtnrunner260]

Powder selection will change a bit if going to lighter projectile, but if you pick something that is on the faster side of the options above, that will probably be fine for the lighter copper. RL26 looks like a great option for both, same with 7828ssc, N570, 565, 560, and Magnum. Retumbo drops way down the list.

Thanks! I will keep looking for some RL26.
Retumbo is just best I have already on hand.

 

[eoperator]

Thanks! I will keep looking for some RL26.
Retumbo is just best I have already on hand.

Finding r26 in stock is a once or twice in a lifetime event, you may want to invest your time looking for something more available.

 

[Flyjunky]

Finding r26 in stock is a once or twice in a lifetime event, you may want to invest your time looking for something more available.

^^^^ truth

 

[A382DWDZQ]

^^^^ truth

I've seen RL26 available several times this year; Powder Valley had it at the beggining of November, but it sells out fast, and I agree with having a backup load. H1000, H4831, Ramshot LRT, Ramshot Magnum, N570, N560, and W760 all seem to be pretty regularly available lately.

 

[A382DWDZQ]

Brownells has Mag Pro jugs right now also...

 

[Sdvldog1371]

Looking for options with a 18in 6.5 PRC with 8 twist.
Currently using 147 ELD-M with Retumbo.
Getting a fairly compressed load at 57 grs. Went up to 58.4 with no pressure signs. But really have to crunch powder during seating.
57.2 grs is giving 2630 via shooting chrony. 58.4 gave an error so unsure of velocity.
Know I wont have a barn burner but thinking I could get some more speed.
Just found a lb of 4831SSC
Been keeping an eye out for H1000 and RL26.
Are there others powders I should consider?
Does the powder selection change if going to a 125-130gr copper bullet?
Also been using Fed210 for primers.
Thanks

If you stick with the lower side of velocity loss per inch of barrel you're essentially firing a 147gr bullet at 2630+ (25fps*8")=2830 fps from a 26" barrel. For your powder charge you should be getting just about 2800 fps from your barrel length. Is it a new barrel? You may start to see it speed up soon if it is. Consider also you may not be getting a full powder burn with your barrel length using retumbo which means you will be seeing a larger drop in velocity per inch. It would have to be ran through quickload.

 

[mtnrunner260]

If you stick with the lower side of velocity loss per inch of barrel you're essentially firing a 147gr bullet at 2630+ (25fps*8")=2830 fps from a 26" barrel. For your powder charge you should be getting just about 2800 fps from your barrel length. Is it a new barrel? You may start to see it speed up soon if it is. Consider also you may not be getting a full powder burn with your barrel length using retumbo which means you will be seeing a larger drop in velocity per inch. It would have to be ran through quickload.

Yes a new barrel with 55 rounds so far.
That is my thought on the Retumbo as well, not getting a complete burn with short barrel.
Thanks

 

[Sdvldog1371]

Yes a new barrel with 55 rounds so far.
That is my thought on the Retumbo as well, not getting a complete burn with short barrel.
Thanks

Ran powder, projectile and cartridge data through quickload and you're on par with what it is putting out number wise.

Of course I had to make some assumptions. Hornady brass at 62gr H2O volume. I measured some 147 eld-m and used the standard burn rate data for retumbo with a C.O.A.L of 2.955". You're at Max average pressure and according to the app you're 11.9% compressed at 57.2 gr.

You are however at a nearly 100% burn 99.31% and it estimates your velocity to be around 2682 fps.

Velocity from a 26" barrel is estimated to produce 2954 fps with an average velocity loss of ≈34 fps/in of barrel.

 

[mtnrunner260]

Ran powder, projectile and cartridge data through quickload and you're on par with what it is putting out number wise.

Of course I had to make some assumptions. Hornady brass at 62gr H2O volume. I measured some 147 eld-m and used the standard burn rate data for retumbo with a C.O.A.L of 2.955". You're at Max average pressure and according to the app you're 11.9% compressed at 57.2 gr.

You are however at a nearly 100% burn 99.31% and it estimates your velocity to be around 2682 fps.

Velocity from a 26" barrel is estimated to produce 2954 fps with an average velocity loss of ≈34 fps/in of barrel.

Thanks for sharing this!
That is really cool info.
I'm using Lapua brass and C.O.A.L. is 2.930

I got some H1000 and Magnum. Will load up the upper end of rerumbo again and see how the other two do with pressure.
Borrowed a Magneto and plan to shoot through chrony as well.

Are there concerns besides pressure for an overly compressed load?

 

[Sdvldog1371]

Thanks for sharing this!
That is really cool info.
I'm using Lapua brass and C.O.A.L. is 2.930

I got some H1000 and Magnum. Will load up the upper end of rerumbo again and see how the other two do with pressure.
Borrowed a Magneto and plan to shoot through chrony as well.

Are there concerns besides pressure for an overly compressed load?

Pressure is the main concern, that and lack of neck tension causing growth. You could be seating bullets to .020" from lands in a compressed load and the powder could push the bullet out far enough to be into the lands. Then your pressure profile changes as does harmonics.