7mm PRC Optimal powder charge help... update... I give up!!! ... updated again!

[markwondi]

N570 is the ticket.

 

[megalomaniac]

N570 is the ticket.

Personally used in a 22in bbl? Is it not too slow burning?

Now I was thinking hard about using n570 or re33 for the 190s in the 22 incher...

 

[jlanecr500]

Personally used in a 22in bbl? Is it not too slow burning?

Now I was thinking hard about using n570 or re33 for the 190s in the 22 incher...

You'll have to drop down a node as I don't think you can get enough powder in the case to make the node you're on now. See below for n570 with you're current coal and bbl length.

 

[megalomaniac]

You'll have to drop down a node as I don't think you can get enough powder in the case to make the node you're on now. See below for n570 with you're current coal and bbl length.

View attachment 218828

That chart for the 190s? Looks about the same as the one you posted for the 175s

 

[jlanecr500]

That chart for the 190s? Looks about the same as the one you posted for the 175s

Yes, for 175's. It looked like you were questioning the 175, n570, 22" bbl load so I wanted to make sure that you knew it would work. I'll run the 190's later this evening and post it.

 

[jlanecr500]

The QL window below is the 190 Atip with the same coal as before. As I expected, the charge increased 1/2 grain to maintain the node/velocity of the 175. Pressure is quite high. All data on this post is for the 190.

In the table, only 1 powder is below max.

You can drop a node and be safe but you'll lose velocity.

The table gives a number of powder combinations for the lower node.

 

[megalomaniac]

The QL window below is the 190 Atip with the same coal as before. As I expected, the charge increased 1/2 grain to maintain the node/velocity of the 175. Pressure is quite high. All data on this post is for the 190.
View attachment 218869
In the table, only 1 powder is below max.
View attachment 218870

You can drop a node and be safe but you'll lose velocity.
View attachment 218871
The table gives a number of powder combinations for the lower node.
View attachment 218872

Perfect and ty again!, the 3rd and 4th image gives me a good place to work around with different powders. I'd be fine in the low to mid 2700s with the 190s

 

[jlanecr500]

Perfect and ty again!, the 3rd and 4th image gives me a good place to work around with different powders. I'd be fine in the low to mid 2700s with the 190s

When you get the 190's, let me know the new starting coal and I can dial it in closer.

 

[infoman jr.]

Still hoping Lapua picks up the 7 prc... but at the moment, I think Hornady and Peterson are the only manufacturers of 7 prc brass. I'll get some.peterson on order, as I've heard it's decent brass, better than Hornady

Gunwerks and ADG also make brass for it.

Gunwerks in stock here

ADG in stock here

*full disclosure I work for ADG

 

[megalomaniac]

When you get the 190's, let me know the new starting coal and I can dial it in closer.

Couldn't find vvn570, but was able to get staball HD. That is some fine ball powder, meters great!

Touching lands COL is 3.460"
Since the 175eldx liked a jump, I'm starting my optimal charge weights in 0.3g increments of Staball HD from 66.3g up to 69g (max listed is 68.7 with COL of 3.340). These are some crazy sleek looking bullets!

Also doing optimal powder charge for the 180g ELD-.M bullets from 66.8 to 69.5g (max is 69.2 at 3.920 COL). I'm testing at 3.340 COL... 3.410 is touching lands.

 

[megalomaniac]

These newfangled high BC bullets are crazy... the 150 NBT I shot out of my 7mag for years next to the 190 Atip Match bullets

 

[megalomaniac]

Also crazy there is this much horsepower out of a compact 5lb 6oz rifle!

(add a couple extra pounds for all the goodies attached)

 

[Remi]

If the 180 eldm behaves and kills like the 6.5 140 eldm and the 108 6mm eldm it would be hard to pass that one up.

 

[megalomaniac]

If the 180 eldm behaves and kills like the 6.5 140 eldm and the 108 6mm eldm it would be hard to pass that one up.

I've never shot hornady bullets before... from what I can gather, the eld-x have twice the jacket thickness over the eld-m's, plus the interlocking ring. Both still have a very soft core. Lots of reports of the eld-xs exploding, but thats at high impact velocities. At 2800fps MV, I'm thinking the eld-xs will be superior on game out to about 500y or so, then after that, the eld-m's will outperform terminally due to the lower impact velocity and their increased frangibility compared to the eld-x's. But again, that's all just theoretical from what I can gather from research.

I won't shoot a game animal past 600, and most of my shots will be in the 200-250ish range.

 

[Remi]

I've used the eldm's quite a bit and seen them used quite a bit, all inside 150yds, I've not had as much exposure to the eldx. From what I've seen I'll stick with the eldm. I'm not sayin the eldx is bad because it's not but the eldm has showed zero reason to change.


108's at 3170fps via 6cm
140 eldm at 2752 cis 6.5cm


Here is a pic of all the bullets recovered from whitetails and hogs.

 

[Remi]

180 Scenar is another with good reviews

180 gr Scenars in 7MM PRC

Has anyone used the 180 Scenars in their 7 PRC? I use the 139’s in my 6.5 Creedmoor and the 150’s in my 7-08. Looking for a target/hunting bullet. They seem very accurate and not fussy when working on a load. I have H1000 on hand. Thanks

www.24hourcampfire.com

 

[megalomaniac]

Went to the range to shoot for powder charge for the 180 match and 190g match bullets...

First shot with the 150nbt's I loaded up for bbl break in.

Started at the bottom end of the ladder with the 180s (2g under book max) and immediately had pressure signs with heavy ejector marks, velocity 2650 fps.

Switched to the 190s and the third round (1.7g under book max) had heavy pressure signs. velocity 2650 fps.

Just ridiculous... I can get these velocities with 175s out of a .308

For kicks and giggles, I brought my 175 eldx's that I had worked up to 2800 fps earlier to shoot at 300 and 500y. Welp, first shot, 2800 fps, VERY sticky bolt lift, crazy ejector marks, case ruined.

I'm thinking something is out of spec with the chamber from the factory.... like maybe the end of the brass at the neck is contacting the end of the chamber pinching the bullet. Brass was trimmed to factory trim length before each firing, so it isn't my brass stretching and me forgetting to trim.

Heavy carbon build up at the throat could possibly cause this... but this rifle only has 70 rounds down it or so...

Any other thoughts???

Never had anything like this before, which is why I'm considering it's a chamber out of spec....

Got 2 boxes factory ammo on order (pains me to do so... I haven't bought any factory ammo in 30 years). If they do the same thing, rifle is going back to manufacturer. If they give me 2950fps w/o pressure, then obviously I'm doing something WAY wrong and I'll have to suck it up and shoot factory ammo

 

[Omega]

Went to the range to shoot for powder charge for the 180 match and 190g match bullets...

First shot with the 150nbt's I loaded up for bbl break in.

Started at the bottom end of the ladder with the 180s (2g under book max) and immediately had pressure signs with heavy ejector marks, velocity 2650 fps.

Switched to the 190s and the third round (1.7g under book max) had heavy pressure signs. velocity 2650 fps.

Just ridiculous... I can get these velocities with 175s out of a .308

For kicks and giggles, I brought my 175 eldx's that I had worked up to 2800 fps earlier to shoot at 300 and 500y. Welp, first shot, 2800 fps, VERY sticky bolt lift, crazy ejector marks, case ruined.

I'm thinking something is out of spec with the chamber from the factory.... like maybe the end of the brass at the neck is contacting the end of the chamber pinching the bullet. Brass was trimmed to factory trim length before each firing, so it isn't my brass stretching and me forgetting to trim.

Heavy carbon build up at the throat could possibly cause this... but this rifle only has 70 rounds down it or so...

Any other thoughts???

Never had anything like this before, which is why I'm considering it's a chamber out of spec....

Got 2 boxes factory ammo on order (pains me to do so... I haven't bought any factory ammo in 30 years). If they do the same thing, rifle is going back to manufacturer. If they give me 2950fps w/o pressure, then obviously I'm doing something WAY wrong and I'll have to suck it up and shoot factory ammo

Run a scope down it and see if there is any buildup, or if your freebore is short or non existent. Might want to do a chamber cast too to see what you are dealing with.

 

[megalomaniac]

Christensen Arms Ridgeline FFT in 7mm PRC

I just received my Ridgeline FFT in 7mm PRC. It took about 4 months for it to arrive. I mounted a Athlon Midas HMR on it with Talley rings. The FFT stock finished with the Sitka camo is nuch nicer in person. The rifle less scope weighs 5.7 lbs on my bathroom scale so take that as you will...

www.longrangeonly.com

Looks like this issue is common in the Ridgeline ffts in 7prcs.

Rifle manufacturer blames ammo manufacturer. Ammo manufacturer blames rifle manufacturer.

If the factory ammo also gives me high pressure, Christenson arms better replace the rifle and I'll just go with .308

 

[hittingsteal]

Bought a new factory Chriatenson Arms Ridgeline FFT in 7mm PRC a few weeks ago. Loaded up 47 factory 2nds 150g NBTs with a middle of the road powder charge of Re22 for bbl break in (box of 50 Hornady brass, pitched 3 right away due to extreme weight variances from mean).

Broke in the bbl with the shoot, clean... shoot 2, clean... shoot 3, clean.. shoot 4, clean... then shoot 5 and clean in between 5 shot strings until I finished off 40 rounds. Only going 2800fps average, book says they should have been closer to 3000 fps. No pressure signs, but one piece of brass during the break in had a slightly stick bolt lift and ejector marks.

Annealed the brass, left the 1 with ejector marks off to the side, then resized bumping the shoulder back 0.003in. Then switched to the 175 ELD-Xs and Re 25 to find optimum charge. Started at 66.0g working up to 68.7g in 0.3g increments (book max is 68.4g). Seated all bullets 0.020 off jam. Neck tension felt equal between all rounds, and seating them was butter smooth.

Shot the first 9 and found what I think is the optimum charge at 67.5g, but only going 2829fps (book says should be around 2950). Problem is, I was getting erratic pressure signs... see image.. light ejector marks at 66.9, but not at 67.2. Light ejector marks at 67.5, but not at 67.8, nor 68.1. Heavy ejector marks and sticky bolt at 68.4 (book max). Did not shoot the 68.7g load.

Group seemed to settle down to around 1in around the 67.5 mark as well (0.9in at 150y).

Plan was to take the optimum charge, then start varying seating depths in 0.005in increments to fine tune. But I'm confused by the erratic pressure signs... and also very disappointed I'm getting on average 125fps slower velocities per charge than book. Granted, I have a 22in bbl, and book test bbl was 24in. But I was figuring a loss of 50 to 60 fps, not 125.

Any thoughts on the erratic pressure? I would have thought headspace, but all base to shoulder lengths were measured with a headspace comparator after resizing. Unfired factory brass measures 0.008 less than my chamber, and I didn't overwork the shoulder, just set it back 0.003.

20 thousandths off jam should have kept me off the lands, even if there were bullet to bullet variances in location of ojive, and none of the rounds felt like bullet was touching the lands when I closed the bolt.

Now I'm not really sure where to go from here... just suck it up and accept around 2825fps from the 175s and current powder? Still a little room in the case... but with a 22in bbl, I'm not sure switching to a slower burning powder like magpro, imr 7977, or retumbo which should fill the case completely will be completely burned in a shorter barrel.

Maybe try VV N565? Supposed to have a little more velocity with the double base burn rate, esp in a short barrel?

Hate to do it, but I may have to actually buy a box of factory ammo from Hornady in 7prc to compare.

You need some vv 656 or 570. H1000 would be another great option. I load up 180s berger hybrid

Bought a new factory Chriatenson Arms Ridgeline FFT in 7mm PRC a few weeks ago. Loaded up 47 factory 2nds 150g NBTs with a middle of the road powder charge of Re22 for bbl break in (box of 50 Hornady brass, pitched 3 right away due to extreme weight variances from mean).

Broke in the bbl with the shoot, clean... shoot 2, clean... shoot 3, clean.. shoot 4, clean... then shoot 5 and clean in between 5 shot strings until I finished off 40 rounds. Only going 2800fps average, book says they should have been closer to 3000 fps. No pressure signs, but one piece of brass during the break in had a slightly stick bolt lift and ejector marks.

Annealed the brass, left the 1 with ejector marks off to the side, then resized bumping the shoulder back 0.003in. Then switched to the 175 ELD-Xs and Re 25 to find optimum charge. Started at 66.0g working up to 68.7g in 0.3g increments (book max is 68.4g). Seated all bullets 0.020 off jam. Neck tension felt equal between all rounds, and seating them was butter smooth.

Shot the first 9 and found what I think is the optimum charge at 67.5g, but only going 2829fps (book says should be around 2950). Problem is, I was getting erratic pressure signs... see image.. light ejector marks at 66.9, but not at 67.2. Light ejector marks at 67.5, but not at 67.8, nor 68.1. Heavy ejector marks and sticky bolt at 68.4 (book max). Did not shoot the 68.7g load.

Group seemed to settle down to around 1in around the 67.5 mark as well (0.9in at 150y).

Plan was to take the optimum charge, then start varying seating depths in 0.005in increments to fine tune. But I'm confused by the erratic pressure signs... and also very disappointed I'm getting on average 125fps slower velocities per charge than book. Granted, I have a 22in bbl, and book test bbl was 24in. But I was figuring a loss of 50 to 60 fps, not 125.

Any thoughts on the erratic pressure? I would have thought headspace, but all base to shoulder lengths were measured with a headspace comparator after resizing. Unfired factory brass measures 0.008 less than my chamber, and I didn't overwork the shoulder, just set it back 0.003.

20 thousandths off jam should have kept me off the lands, even if there were bullet to bullet variances in location of ojive, and none of the rounds felt like bullet was touching the lands when I closed the bolt.

Now I'm not really sure where to go from here... just suck it up and accept around 2825fps from the 175s and current powder? Still a little room in the case... but with a 22in bbl, I'm not sure switching to a slower burning powder like magpro, imr 7977, or retumbo which should fill the case completely will be completely burned in a shorter barrel.

Maybe try VV N565? Supposed to have a little more velocity with the double base burn rate, esp in a short barrel?

Hate to do it, but I may have to actually buy a box of factory ammo from Hornady in 7prc to compare.

Retumbo 69.5 190 A tip is good load.
H4831sc 62.8 with 175s