7mm PRC

[H&H Precision Outdoors]

So, what was different in your reloading between first and 2nd rd of testing? Or are we gonna chalk it up to barrel? On 2nd rd, did you do more than 3 rd groups/velocity strings?

You kind of conflated those. Initial load work showed promise, even bragged on best group youd ever shot. Wandered about retumbo and QL prediction and opined about saving components. Sorry you weren't clear about that. If you would have said "computer predictions can be useful if you don't know where to start," I'd have agreed with you. It just sounded weird with your initial load work and best group ever comment.

Nothing was different. Same lot of brass, same primer, same trim length, same powder charge, & same bullet / seating depth etc…

I left the barrel uncleaned, and repeated the test. No I did not retest shot strings greater than three. My reason for that is because if the load I’m retesting doesn’t repeat why shoot more.

(Barrel was cleaned during 1st test and 5 fouling shots were fired on the paper, followed by a 8-10minute cool down.

Normal I shoot x1 shot string of three till
I find something that shows promise. If it shows good ES/SD with acceptable accuracy .5” or better, then I load up another three shoot paper again, and what I’m looking for is consistent ES/SD, similar group size or better, and same point of aim/same point of impact. If the second group repeats, then I load up 6 more retest everything I said above, & if it checks out okay I’ll then test at distance.

Sorry if I wasn’t clear @6brshooter

 

[H&H Precision Outdoors]

Range report:

Berger 190g LRHT
66g H1000 (x3 shot group)
66.50g H1000 (x5 shot group)

Believe I found a solid node here, but still need to confirm that it can repeat itself. Plan to load up 66g, 66.2g, & 66.4g and see if I can repeat similar groups. Muzzle velocity was hovering 2950 +/- 12fps with very acceptable ES. For this being a hunting rifle, I’m extremely pleased thus far.

 

[VikingSinEater]

Thought I would share my load for my MPA Matrix Pro II 7PRC 26”

185 RDF loaded .03 off lands.
Hornady Brass
Remington 9 1/2M
VV N570- 68.7gn
MV 2940fps
ES 19
SD 7
The group was 5 shot and measured at .172” after removing the .284” projectile diameter.

I have since shot 700 of this combo out to 1250 yards and it has been the most consistent load in any rifle I've ever shot. Daily still get 1/3 inch 5 shot groups when I recheck for various temps. N570 has proven to not really give me issues with temps… 110 degrees down to 17 degrees in the past year of shooting. Something I was not expecting…

 

[secondofangle2]

to follow-up on my post on p16

I dropped down to 67.5 (Hornady book max) H1000 and now that the barrel has 75 down it, i'm seeing right at 2900 with SD single digit, so that's where she'll stay. Whorenady brass seems to tolerate that charge. it's at 3.310 abotu 0.03" off lands. It's harder to shoot well than my 15# ring, especially with teh Ultra 7 (come on TBAC, send that Magnus S RR!), but I still think it's probably a 0.75 MOA gun for 10 shots, which is fine for a rifle intended for maximum range 800 yards or so.

I tried retumbo and got no better speeds and almost same pressure at same charge. 69 grains RUINED the Whorenady cases with one shot, I think abotu 67 grains would be max for RETUMBO adn teh 180.

 

[H&H Precision Outdoors]

to follow-up on my post on p16

I dropped down to 67.5 (Hornady book max) H1000 and now that the barrel has 75 down it, i'm seeing right at 2900 with SD single digit, so that's where she'll stay. Whorenady brass seems to tolerate that charge. it's at 3.310 abotu 0.03" off lands. It's harder to shoot well than my 15# ring, especially with teh Ultra 7 (come on TBAC, send that Magnus S RR!), but I still think it's probably a 0.75 MOA gun for 10 shots, which is fine for a rifle intended for maximum range 800 yards or so.

I tried retumbo and got no better speeds and almost same pressure at same charge. 69 grains RUINED the Whorenady cases with one shot, I think abotu 67 grains would be max for RETUMBO adn teh 180.

With only 75 rounds on your barrel, you should see velocity speed up 50fps or so.

 

[secondofangle2]

they started at 2875 so I'm half way there

I cool every 3-4 shots for 5-10 min with high volume RYOBI blower, which probably lengthens the break-in time; plus this is not a large sample test

 

[H&H Precision Outdoors]

they started at 2875 so I'm half way there

I cool every 3-4 shots for 5-10 min with high volume RYOBI blower, which probably lengthens the break-in time; plus this is not a large sample test

Mine really started to stabilize around 150 rounds, and velocity gained was around 50fps. I bet you'll be close to 2925ish.

 

[HungerNSharkTooth]

Love my 7mm prc rifle from fierce

 

[b2948kevin]

I am building a 7 PRC now and I always start by buying my own reamer with custom freebore for the bullet I am going to be primarily shooting. This way I can always chamber up another barrel later.

I am planning on shooting the 190gr A-Tip primarily or exclusively. Anyone have the ideal measurements for base to ogive or simply OAL for the A-Tip on a 7 PRC? I am used to keeping the bullet bearing surface ahead of where donuts form, but I would love to hear if others are doing this or not also.

What I am ultimately trying to do here is answer the reamer manufacturer's question of how much Freebore I want on the reamer which I'll provide to my gunsmith for chambering.

 

[H&H Precision Outdoors]

I am building a 7 PRC now and I always start by buying my own reamer with custom freebore for the bullet I am going to be primarily shooting. This way I can always chamber up another barrel later.

I am planning on shooting the 190gr A-Tip primarily or exclusively. Anyone have the ideal measurements for base to ogive or simply OAL for the A-Tip on a 7 PRC? I am used to keeping the bullet bearing surface ahead of where donuts form, but I would love to hear if others are doing this or not also.

What I am ultimately trying to do here is answer the reamer manufacturer's question of how much Freebore I want on the reamer which I'll provide to my gunsmith for chambering.

I had this done for my 7 PRC hunting rifle I have posted above, however I did not provide my own reamer, all I did was make note on my build sheet that I requested the chambering job to allow enough free bore for the Berger 190g LRHT’s.

With that being said, I could get that info from my smith if you’d like me to. Also I believe the A-Tips are longer than the Berger’s so they won’t be the same.

 

[secondofangle2]

Your best bet is to load up a dummy round and send it to Manson Reimers, and they will design the reamer around that.

If you’ve never done it before, and you go trying to measure this and that and map it onto a known reamer drawing you’re gonna have a high chance of screwing it up. Costly mistake.

The other thing is, you could always use a standard reamer and have your gunsmith extend the free bore. You can always extend the free bore of a standard chamber, but you can’t shorten the free bore if extra is built into the reamer.

It’s not a really big deal, but that reamer is basically a one trick pony And you can start out with the best of intentions about those 190s and wind up changing your mind after you’ve shot a bunch of them and are working on your second barrel

 

[HungerNSharkTooth]

I had mine built by someone else … wouldn’t know where to start to build my own

 

[H&H Precision Outdoors]

Range report:

Loaded up the previous charges and they blew apart along with a retest of 65.50g which did repeat followed by 66.60, & 66.70g of H1000. Seemed to have found a wide velocity node here, and I plan to load up 9 rounds of 66.60g and test the middle node to see if potentially have something, followed by seating depth testing. Here were my results with an average velocity of all three charges being at 2985fps:

Berger 190g LRHT
Federal 215M match primer
Gunwerks (ADG) Brass
H1000 powder

 

[secondofangle2]

,Primer pockets holding up?

 

[H&H Precision Outdoors]

,Primer pockets holding up?

So far I managed to throw a few piece of brass out that were trimmed, & prepped the same as all others because they caused inconsistencies in my velocity and group. Not sure if this batch of ADG is the quality it needs to be.

What’s your opinion on it @secondofangle2

 

[secondofangle2]

I'm using Hornady for load development till Lapua comes out. I have 100 pieces, 20 of them were sacrificed to the pressure gods. 30 pieces have loosening but useable pockets.

The other 50 pieces have never seen more than 67.5 grains of H1000 with 180 grain bullets and should last the typical 10 or so cycles, I'm guessing.

I purposefully got junk brass for load development. I throw it away without a twinge of regret.

 

[H&H Precision Outdoors]

I'm using Hornady for load development till Lapua comes out. I have 100 pieces, 20 of them were sacrificed to the pressure gods. 30 pieces have loosening but useable pockets.

The other 50 pieces have never seen more than 67.5 grains of H1000 with 180 grain bullets and should last the typical 10 or so cycles, I'm guessing.

I purposefully got junk brass for load development. I throw it away without a twinge of regret.

Then that makes me feel like my assumption is right about my ADG Gunwerks brass. Some pockets are loose and I can feel it when I use my hand priming tool. Also some are good and when I run into a bad one it shows on my chronograph and groups. I’ve been throwing them out when I run into one like that.

 

[lash]

Then that makes me feel like my assumption is right about my ADG Gunwerks brass. Some pockets are loose and I can feel it when I use my hand priming tool. Also some are good and when I run into a bad one it shows on my chronograph and groups. I’ve been throwing them out when I run into one like that.

I’ve not had any issues with my ADG brass, but I didn’t buy it from Gunwerks. I have two hundred pieces that are very consistent and haven’t run into any loose pockets, even though I’m using pretty hot Retumbo loads to push 190s around 2980.

 

[H&H Precision Outdoors]

I’ve not had any issues with my ADG brass, but I didn’t buy it from Gunwerks. I have two hundred pieces that are very consistent and haven’t run into any loose pockets, even though I’m using pretty hot Retumbo loads to push 190s around 2980.

I’m running H1000 with Berger 190g’s at AVG 2985fps. I’ll probably send the rest of the week short out bad brass that cause fliers etc… then sort the ones that gave me good groups, prep them, & then retest.

 

[lash]

I’m running H1000 with Berger 190g’s at AVG 2985fps. I’ll probably send the rest of the week short out bad brass that cause fliers etc… then sort the ones that gave me good groups, prep them, & then retest.

H1000 is a faster powder and maybe you’re getting higher pressures as a result.

 

[H&H Precision Outdoors]

H1000 is a faster powder and maybe you’re getting higher pressures as a result.
[/QUOTE

I’m running H1000 with Berger 190g’s at AVG 2985fps. I’ll probably send the rest of the week short out bad brass that cause fliers etc… then sort the ones that gave me good groups, prep them, & then retest.

I don’t thing I have pressure issues at all, I can take the rifle out one day and print .2” - .4” 3 shot groups of 3 strings, and one day it blows apart, again no pressure issues. I’ve shot this load close to 8 different times 5 of them in the range above and 3 that blew apart or hand one flyer.

 

[secondofangle2]

This is the first I’ve ever heard of post hoc sorting of brass to eliminate flyers. And to be honest, I’m not sure it makes very much sense. Because there are many causes for “flyers“ the first probably being the shooter and the stochastic nature of the entire process - that is, dispersion.

Now, if you’re talking about velocity outliers, and you made a note of each case and then measured the capacity of water, and found that the fast ones were lower on volume, and the slow ones were higher on volume, I can see doing that - even though I still think you’re gonna throw away a lot of perfectly good brass that was not responsible for the variation. You could also just measure all of the cases upfront and cull the capacity outliers, and therefore eliminate that variable from consideration.

The final thing I will say and this is not to get on your case, but if your primer pockets are expanding, you are over pressure. Full stop.

 

[b2948kevin]

Sorry, I’m just catching up and have been away on business travel for a bit. This is great information.

I had this done for my 7 PRC hunting rifle I have posted above, however I did not provide my own reamer, all I did was make note on my build sheet that I requested the chambering job to allow enough free bore for the Berger 190g LRHT’s.

With that being said, I could get that info from my smith if you’d like me to. Also I believe the A-Tips are longer than the Berger’s so they won’t be the same.

Sorry, I’m just catching up and have been away on business travel for a bit.

Great info, thank you for the help. Lots of great replies here and I am thinking I might just have the gunsmith use a throat reamer for optionally down the road.

H&H, I’d love to know what your freebore length is. You appear to be getting g great results.

Also, are you seating those far enough for the straight walls of the bullet to protrude into the “donut zone”? In other words, are your A-Tips seating deep enough that the rear-most section of the straight walls of the bullet (just above the boat tail) touch or go down past the casing’s neck/shoulder junction? I usually try to keep my bullets seated above this so as not to have issues later if or when donuts form in the casing. Was wondering if you are doing the same.

 

[H&H Precision Outdoors]

This is the first I’ve ever heard of post hoc sorting of brass to eliminate flyers. And to be honest, I’m not sure it makes very much sense. Because there are many causes for “flyers“ the first probably being the shooter and the stochastic nature of the entire process - that is, dispersion.

Now, if you’re talking about velocity outliers, and you made a note of each case and then measured the capacity of water, and found that the fast ones were lower on volume, and the slow ones were higher on volume, I can see doing that - even though I still think you’re gonna throw away a lot of perfectly good brass that was not responsible for the variation. You could also just measure all of the cases upfront and cull the capacity outliers, and therefore eliminate that variable from consideration.

The final thing I will say and this is not to get on your case, but if your primer pockets are expanding, you are over pressure. Full stop.

Some good point made @secondofangle2
I’m didn’t throw any brass away yet, but I did sort the ones that gave good groups, and the ones that cause fliers or didn’t group consistently.

The charge I’m running is 66.60g H1000 which is was under pressure for my rifle. I was able to run my ladder test in the beginning up to 69g’s before pressure.

Also I’ll own it when I pull a shot 100% but the groups I shot that have me these results were all clean trigger pulls and fundamentals.

 

[H&H Precision Outdoors]

Sorry, I’m just catching up and have been away on business travel for a bit. This is great information.

Sorry, I’m just catching up and have been away on business travel for a bit.

Great info, thank you for the help. Lots of great replies here and I am thinking I might just have the gunsmith use a throat reamer for optionally down the road.

H&H, I’d love to know what your freebore length is. You appear to be getting g great results.

Also, are you seating those far enough for the straight walls of the bullet to protrude into the “donut zone”? In other words, are your A-Tips seating deep enough that the rear-most section of the straight walls of the bullet (just above the boat tail) touch or go down past the casing’s neck/shoulder junction? I usually try to keep my bullets seated above this so as not to have issues later if or when donuts form in the casing. Was wondering if you are doing the same.

I can get that info for ya on the free bore, and I’m currently 0.020 thou off the lands without any seating depth testing done.

I always do seating depth testing to make sure I’m in the middle of a node.

 

[Gtscotty]

I've been having good luck with 69gr to 69.5gr Grand under 180gr ELDs, 175gr ELDx and most recently 175gr ABLRs (blems to boot). A little over 2,800 fps out of the 19" should do everything I need if I can draw a cow tag this year. Last thing I need to do is rig up a more permanent raised cheek rest on the stocky stock, thinking I might try to draw up and 3d print something.

 

[lash]

You don’t like the current cheek pad with storage that’s on there now? Guess Armageddon Ger? It isn’t as cold or hot as something solid or plastic.

 

[WilburW]

Anybody have experience with 160CX and H1000?
Initial tests with 67 and 68 gr were not very encouraging. Hornady book max was 69.5 for this combination, but seems low compared to other projectile results reported here…

 

[H&H Precision Outdoors]

Anybody have experience with 160CX and H1000?
Initial tests with 67 and 68 gr were not very encouraging. Hornady book max was 69.5 for this combination, but seems low compared to other projectile results reported here…

For that 160g CX, I’d start with H4831sc, N560, or N555. Should suit you better than H1000 because of bullet weight.

 

[Gtscotty]

Why? Both the Hornady load data and Hodgdon show higher velocities with H1000 speed powders, and even slower than H4831 speed, in 160gr class bullets. I've played with H4831sc in 7 PRC a little, but didn't see any apparent benefits over the slower powders I've used that better fit the expansion ratio like H1000, Grand, RL-26 Retumbo, or even Staball HD, most of that was with 175s, but the copper 160gr data is between the 160gr and 175gr lead core data, as you'd expect. Other than LRT and Retumbo, all other powders in the data hit pressure before they hit max volume with lead 160gr, and I wouldn't put any money on accuracy with H4831 being better than H1000 just because it's faster burn rate and slower MV.

 

[Gtscotty]

Anybody have experience with 160CX and H1000?
Initial tests with 67 and 68 gr were not very encouraging. Hornady book max was 69.5 for this combination, but seems low compared to other projectile results reported here…

I've been playing with the 160gr CX a little bit, mostly with Grand, which is right next to H1000 on the burn rate chart. I think that's probably a good burn rate for this bullet but I also would expect to see velocities a little lower than similar weight lead bullets, or at least that's always been my experience shooting copper bullets. How far are you loading off the lands? I still have more work to do on my 160gr CX loads, but so far 65 thou and 85 thou off seem to shoot better than closer to the lands.

Here's a spread I shot with Grand before I started load work, obviously similar burn rate doesn't mean same charge weights, in general Grand charge weights are higher, but I'd expect H1000 to pressure out a little bit slower. This is a 19" barrel, so if your barrel is longer you might see higher velocities with H1000. I'd have to check my notes at home, but I think 71gr 65 or 85 thou off was the best group so far. Accuracy hasn't been as good as 175gr ELDx, 175gr ABLR or 180gr ELD yet, but not wildly bad or anything. I think I need to fiddle with seating depths some more and maybe try H1000 with these bullets.

 

[H&H Precision Outdoors]

Why? Both the Hornady load data and Hodgdon show higher velocities with H1000 speed powders, and even slower than H4831 speed, in 160gr class bullets. I've played with H4831sc in 7 PRC a little, but didn't see any apparent benefits over the slower powders I've used that better fit the expansion ratio like H1000, Grand, RL-26 Retumbo, or even Staball HD, most of that was with 175s, but the copper 160gr data is between the 160gr and 175gr lead core data, as you'd expect. Other than LRT and Retumbo, all other powders in the data hit pressure before they hit max volume with lead 160gr, and I wouldn't put any money on accuracy with H4831 being better than H1000 just because it's faster burn rate and slower MV.

Main reason why I would choose those over a slower burning powder is because of the bullet weight, and also depending of barrel length. When I reload I personally don't chase speed because its not necessary. Rule of thumb for me, and many of the greats out their slower burning powder for heavier bullets, faster burning powder for lighter bullets. To each of your own, you can pick what you want but these are my choices if I were to pick.

 

[WilburW]

I have seen powder tests showing better groupings with H4831sc, but it is out of stock everywhere. Since I still have 2.5 lbs of H1000, I thought I’d try to find a load that shots in my 20” Bergara.
Very initial results. Not yet testing seating depth. Seated to Hornady published COAL of 3.290, which is about 0.075” off the lands. Rather than wasting bullets and powder, I thought I’d get some leads here.

67 gr: n=5, avg=2901, SD=4.7, 2” group.
68 gr: n=4, avg=2968, SD=28, 2.5” group.

 

[WilburW]

For comparison, immediately after the above, with the same rifle, the Barnes 160 LRX Factory shot:
N=6, avg=2998,SD=15.8. Group=0.65” OAL=3.320.
Very impressive from a factory load.
So, my rifle is capable of these excellent results.
Just need to find a comparable hand load.

 

[secondofangle2]

I think that the notion that there is a correct powder burn rate for a given caliber and bullet weight is largely a myth. It reminds me of the myth that you should have near 100% case fill and Brian Litz found that that is actually the opposite of the truth

If you use too fast burning of a powder, you are going to get high pressure before you achieve optimal velocity, and if you use too slow burning of a powder, you won’t be able to fill the case with enough of it to get optimal velocity. Those are the only two things I think are uncontroversial about burn rate versus bullet weight.