7mm PRC

By the way, those rounds are loaded to 3.320 inches.

My gunsmith used a Manson reamer, the standard one they have off the shelf with a slightly different base diameter, and he did not add any additional free bore. My COAL for a 180ELD – M touching the lands is 3.330“.

Just an FYI, for anybody considering getting one of these spun up. That COAL puts the top of the boat tail right at the bottom of the neck for that bullet. I wouldn’t see a point of extending the free bore unless you were shooting a solid or a 190 class bullet that is longer.
I was just curious, as I’m also using a long action (cut de gras) and have a single metal mag for it. The mag works great and is tight with no rattling. Those MDT mags were not out when I put mine together. I’m shooting 190s also seated to a COAL of 3.435”.

And yes mine is throated a bit longer for their use.

ETA: in an MDT ACC LA chassis.
 
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My 7 PRC is at the G'smith.
I touch the lands at the following COL values below:
-175 ELDX 3.260"
-180 ELDM 3.191"
-180 Berger Hybrid Target 3.373"
-190 A-tips 3.495"

All values are avg out of 5 measurements per bullet. Decided to borrow a friend's factory rounds of 175 ELDX and 180 ELDM and forced the bolt to close. As expected, bullet got stuck in chamber.

Used Hornady's OAL length gauge with their 7 PRC modified case AND Sinclair's OAL gauge with an actual used piece of brass and values are very close. Even had a fellow buddy measure to find out where my lands are to make sure I'm not going crazy.
 
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My 7 PRC is at the G'smith.
I touch the lands at the following COL values below:
-175 ELDX 3.260"
-180 ELDM 3.191"
-180 Berger Hybrid Target 3.373"
-190 A-tips 3.495"

All values are avg out of 5 measurements per bullet. Decided to borrow a friend's factory rounds of 175 ELDX and 180 ELDM and forced the bolt to close. As expected, bullet got stuck in chamber.

Used Hornady's OAL length gauge with their 7 PRC modified case AND Sinclair's OAL gauge with an actual used piece of brass and values are very close. Even had a fellow buddy measure to find out where my lands are to make sure I'm not going crazy.
Freebore a bit short eh?
 
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I don't know yet. Waiting on g'smith. Is it weird to have a very short COL when using X and Y bullets but yet COL is fairly normal when using bigger Z and A bullets? My PRS gun is 6BR and it has a short freebore for all 6mm bullets.
Coal will be different for sure. Base to ogive should be pretty consistent between all the bullets, likely within 0.010"
 
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I agree with this IF that person doesn't have mags for their PRC yet. I bought 2 of those MDT mags to compliment my existing Accurate RUM/PRC 3.850 mags and had to remove material off the MDT's so they can latch properly.
-When the Accurate latches, the MDT's wouldn't latch.
-Adjusted the mag latch down on the XLR chassis so all mags latch but started having feeding issues with the Accurates.
-Went back to original latch position and removed material off the top of the MDT's. No problems.
And @secondofangle2

Update. I checked with technical services at MDT. That polymer mag will not work with my Oryx chassis, hence the use of the metal 5 rd mag for .300 WM.

I have not had a single feeding problem, by the way. And the feed lips are just right for single feed by hand.
 
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Most of my rifles are v heavy "crew served weapons". This is my very first "lightweight" hunting rig.

Related: My buddy has the factory Savage with titanium action and 20" Proof in MDT and is running a TBAC Ultra 7 and I thought it was going to thump with 180 grains. It was surprisingly pleasant to shoot. (I still haven't shot mine yet, which weighs in about a pound more than his.)
 
I had a Savage impulse big game in 7prc on order as I was happy with a predator in 308 but then got a dud barrel on a 6.5PRC elite precision, I didn't write the barrel serial and I don't think it made it onto the registration, I sent it for warranty with the Australian supplier and I'm 99% sure they sent it back with the same barrel as it developed the same peculiar carbon deposit near the muzzle and shot like shit when they sent it back to me. Most Savages have mad chatter the whole way down the barrel so that didn't bother me but I suspect the bore opened and was gas cutting projectiles or causing odd barrel exit behaviour.

Especially outside Northern Territory or the Caoe in Queensland where there are buffalo and scrub bulls, 7prc is probably the perfect cartridge for hunting in Australia as it should easily deal with any deer, pigs or camels here with good balistics without too much recoil.

I eventually try a Ruger M77 as I don't have a control round feed rifle yet.
 
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I had a Savage impulse big game in 7prc on order as I was happy with a predator in 308 but then got a dud barrel on a 6.5PRC elite precision, I didn't write the barrel serial and I don't think it made it onto the registration, I sent it for warranty with the Australian supplier and I'm 99% sure they sent it back with the same barrel as it developed the same peculiar carbon deposit near the muzzle and shot like shit when they sent it back to me. Most Savages have mad chatter the whole way down the barrel so that didn't bother me but I suspect the bore opened and was gas cutting projectiles or causing odd barrel exit behaviour.

Especially outside Northern Territory or the Caoe in Queensland where there are buffalo and scrub bulls, 7prc is probably the perfect cartridge for hunting in Australia as it should easily deal with any deer, pigs or camels here with good balistics without too much recoil.

I eventually try a Ruger M77 as I don't have a control round feed rifle yet.
So, it is more likely a case of putting bison on the barbecue than shrimp. Awesome.
 
190 A Tips over N570 just work….
 

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So Lapua brass is a good thing.


I'm not sure if I ever posted these, fresh barrel so it should speed up a little, but Hornady factory 7prc is known slow. Will be running mostly 190Atip when I hand load for it. Hopefully the spread on the factory ammo does settle a bit with a few more rounds down. 32 inch Lothar Walther. 175ELDX & 180eldm
 

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Took my Defiance AnTi-X (pictured above) to the indoor 100 yard tunnel range tonight in SLC. Specs are long action, 24" proof 1-8.4 twist, Leupold 3-15x44 scope XLR Element 4.0 magnesium, Hellfire 3 port brake, Harris bipod, unfired till tonight. Spun up by Eric Smith at ES-Tactical, and he always does phenomenal work. Took 3 rounds to get centered then I fired the following loads in the chart below. I would not pay attention to the SD, there are several reasons I won't elaborate upon, why they are all over the place (part of it is the tunnel itself messes with the radar). Also, the first group of 4 was right at 0.5", one ragged hole. They deteriorated after that, I thought it was me getting my cage rattled in the tunnel, then I realized I never torqued down the side bolts to the rings beyond finger tight! And the scope was loose, and my crescent wrench was missing from my range bag, so I called it quits after that discovery. Anyway, I'm posting this data for velocity and pressure information. Only the last one of the 69.0 grains of H1000 in Hornady brass had just slight increase bolt lift, and an ejector mark. I usually back down from that a grain, so I think I'm going to settle on 68 grains. (QL thinks 68 grains is 106.7% full [not even close!], gets 62342 PSI, and produces 2886 fps - so close to my results and almost max velocity/pressure on QL, FWIW.) All cci 250 (as if that matters). COAL is 3.310, which is .025" off the lands. The 69 grain one is 99+% full - I can barely hear it rattle and there is no crunch. QL thinks this should be 108% full for some reason that is beyond me - this is not a compressed load AT ALL. The case capacity is just shy of 82.0 grains H20. Ambient temperature was about 65 degrees in the tunnel, but the ammo started at about 40 degrees and I warmed the rounds up (a little) in my pocket before firing. Powder humidity was 48.5%RH at the time of reloading and at 60 degrees F. Also, I never shot more than 3 rounds before cooling the barrel with my Ryobi inflator gizmo - this is my first time with a Proof and they do indeed heat up and require some real air movement or time to cool off!

Final analysis: 2900-2950 fps is definitely possible with 180 ELD-M and H1000 in some guns, even with Hornady brass (gasp!). Assuming this barrel will "speed up" as they are rumored to do, 2950-3000 fps is possible. These velocities may change as I transition to Lapua brass later this year (hopefully). Wheeler or Ackley or one of the wildcat guys said on the forums about 10+ years back that you should do load development in weak brass as a worst case test - if you're at/under pressure there, you should have a good margin of error for strong brass, which can hide excessive pressure because it's so strong. I like that idea, because I like to have a good margin of error for temperature changes, lot-to-lot changes, powder humidity changes, etc. Hence, I will be using these same 50 pieces of Hornady brass and see where things settle out, rather than chase speed and blame the brass as I have seen others tempted to do. I have not checked the primer pockets on the 69 grain loads yet - but they are neither flat nor cratered.

PowderCharge 175 ELD-XCharge 180 ELD-MCharge 180 ELD-MCharge 180 ELD-M
H1000
67.0​
68.0​
68.5​
69.0​
2841.0​
2887.0​
2930.0​
2964.0​
2855.0​
2868.0​
2971.0​
2966.0​
2828.0​
2920.0​
2956.0​
2960.0​
2832.0​
2910.0​
2929.0​
2778.0​
2929.0​
2872.0​
2944.0​
2895.0​
2912.0​
2895.0​
2918.0​
AVG
2834.3​
2896.3​
2943.2​
2963.3​
SD
21.7​
18.8​
13.8​
2.2​
 
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^I would edit the post, but I'm afraid it will get lost.

The primer pockets of all loads >= 68 grains are showing stress/loosening, despite no clear evidence of other traditional measures of overpressure loads.

So, other posters are correct, Hornady brass is too soft in the web/base. You can probably make it to 69 grains with ADG/Peterson/Lapua.

I'm going to back down to 67.5 (book max) till she's broke in and Laupa brass comes out.
 
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^I would edit the post, but I'm afraid it will get lost.

The primer pockets of all loads >= 68 grains are showing stress/loosening, despite no clear evidence of other traditional measures of overpressure loads.

So, other posters are correct, Hornady brass is too soft in the web/base. You can probably make it to 69 grains with ADG/Peterson/Lapua.

I'm going to back down to 67.5 (book max) till she's broke in and Laupa brass comes out.
You know, the Atlas brass is really very good. I’m happy with it and feel no need to wait and pay more for Lapua. With the ADG brass I had really good results with 68gr H1000.
 
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I've been using adg brass, cci 200 and 70gr h1000 with 183smk and 184 f open. Smk are running 2998 and the f opens are running 3025. I quit the 183smk due to bullet inconsistencies, as much as .025 diff in length. When I watermarked the loads at 950 and 1400, the smk had 3x as much vert. Shot without windflags. Smk@950, felt great and didnt have any called off-shots
1000001887.jpg

184 bergers@950
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Can't seem to find the 184group at 1400, but here's the 183smk:
1000002517.jpg

They are about 75% consistent, but the variation on the outliers are ugly. Here's the rifle, cdg long action with 26" pva m24 contour in a bedded a5.
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The 183 group was the last of those i had loaded up, they shot way better when doing loadwork. They shot so bad i fired a 3rd group of 184s to check that something wasn't wrong with the rifle, lol.
1000002531.jpg
 
I'll join in this H1000 love fest, my current load data:

67.2gr of H1000
Peterson brass
Berger 190gr LRHT
Fed 210

27" barrel. 2,915 fps. It doesn't seem like a hot load, easy extraction and no primer pressure signs and it's been good in the rain. I never pushed past 67.6gr since the speed was plenty for a 190gr.
 
Shot my 7 prc for the first time today. The speed was significantly slower than hodgdon data but I think others are seeing similar.

Hodgdon had me at 2950 with 64.5g h1000

Barrel: 26” kreiger
Brass: ADG
Primer: 215m
Powder: 64.5gn H1000
Bullet: Berger 180 hybrid

Actual speed: 2770 (15 shot group)
Sd: 8.3
Es: 25

This was very inline with what Hawkins write up had. I just have never seen the book that far off

IMG_8101.jpeg
 
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Wry nice build.

And yeah, I don’t see anyway that you would get 2950 with 215s in a 26” barrel. Not with that powder charge anyway. I think it’s a stretch no matter what powder.

Looking through here there’s quite a few guys doing it with 68-70 grains.

I was just surprised because the hodgdon book said 2950 with a 24”. I’ve never had the book be that far off

IMG_8102.jpeg
 
My test with stabil hd, win mag primers and 180eldm was less than great, in fact it was pretty sad. I fouled the bore with some factory 180eldm, ave 2895 fps over 10rds.
1000004098.jpg

I almost hate showing the stabil hd groups, I started to wonder if I forgot how to shoot after the 3 weeks of snow /ice on the ground.
1000004099.jpg

I finally got depressed and needed a smile, shot my regular load of 184 f opens in adg brass, cci 200, and 70gr h1000. I shanked 5th shot but fired a 6th rd on a separate bull and it would have been in the bughole with first 4rds.
1000004216.jpg
 
Fixing to begin loading my custom 7 PRC hunting rifle. All brass (ADG) has been fire formed, and barrel has officially speeded up. This rifle seems to have great ES/SD across many powder charges with H1000 in my 1:8 Bartlein CW 26” M24/M40 barrel. Gonna experiment with the Berger 190g LRHT, 184g Hybrids, & 180g Hybrids. Will share data as I progress with finding a repeatable load for the rifle, picture posted below:

Specifications:
Builder: Altus Shooting Solutions
Defiance Deviant Tactical (DLC) “Bedded”
TriggerTech Diamond single/pro curve
26” Bartlein CW M24/M40 1:8
APA Gen III little bastard .30 Cal
Hawkins Precision Hunter DBM
Carbon McMillan U10 w/4” ARCA & 2” picatinny
Spuhr 1.35” Rings
Nightforce NX8 4-32x50mm F1
 

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Fixing to begin loading my custom 7 PRC hunting rifle. All brass (ADG) has been fire formed, and barrel has officially speeded up. This rifle seems to have great ES/SD across many powder charges with H1000 in my 1:8 Bartlein CW 26” M24/M40 barrel. Gonna experiment with the Berger 190g LRHT, 184g Hybrids, & 180g Hybrids. Will share data as I progress with finding a repeatable load for the rifle, picture posted below:

Specifications:
Builder: Altus Shooting Solutions
Defiance Deviant Tactical (DLC) “Bedded”
TriggerTech Diamond single/pro curve
26” Bartlein CW M24/M40 1:8
APA Gen III little bastard .30 Cal
Hawkins Precision Hunter DBM
Carbon McMillan U10 w/4” ARCA & 2” picatinny
Spuhr 1.35” Rings
Nightforce NX8 4-32x50mm F1

Range report from today:

Started with a clean barrel, followed by 3 fouling shots. Starting charge weights: 67g H1000, 67.5g H1000, & 68g H1000. Running 184g Berger Hybrid, Gunwerks Brass, Fed 215 Match Primer, & 0.015 thou off lands. All groups were acceptable with single digit SD’s and ES of less than 18. Note these are all 3 shot groups, & nothing has been confirmed yet.
 

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No pressure at 68 grains?
I had none in my barrel, and I don’t plan to try to push higher since the muzzle velocities for all charges were 3000fps -0+30fps. My original goal was to be at 3000fps so a node around this is fine for me.

Also, the first group with 67g H1000 was the best group I’ve shot in my entire life. I literally had to stop and run down to 100 yards cause I couldn’t believe it lol!
 
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Fixing to begin loading my custom 7 PRC hunting rifle. All brass (ADG) has been fire formed, and barrel has officially speeded up. This rifle seems to have great ES/SD across many powder charges with H1000 in my 1:8 Bartlein CW 26” M24/M40 barrel. Gonna experiment with the Berger 190g LRHT, 184g Hybrids, & 180g Hybrids. Will share data as I progress with finding a repeatable load for the rifle, picture posted below:

Specifications:
Builder: Altus Shooting Solutions
Defiance Deviant Tactical (DLC) “Bedded”
TriggerTech Diamond single/pro curve
26” Bartlein CW M24/M40 1:8
APA Gen III little bastard .30 Cal
Hawkins Precision Hunter DBM
Carbon McMillan U10 w/4” ARCA & 2” picatinny
Spuhr 1.35” Rings
Nightforce NX8 4-32x50mm F1
Interested in the 190 LRHT results.
 
I’m getting 2890 in a 30” barrel using 68gr Retumbo in ADG brass with zero pressure signs, room for more and excellent accuracy. Sorry, not H1000.
Was very curious about potentially trying Retumbo in my 7 PRC 26" Bartlein. Do you think think my barrel is sufficient enough to give me a 100% burnt propellent with the 180g's - 195g Bergers in ADG brass, Fed 215m Match Primers?
 
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Was very curious about potentially trying Retumbo in my 7 PRC 26" Bartlein. Do you think think my barrel is sufficient enough to give me a 100% burnt propellent with the 180g's - 195g Bergers in ADG brass, Fed 215m Match Primers?
I honestly can’t tell you with certainty. I know that I’m using a suppressor and see zero evidence of left over powder in my 30” barrel, but you’ll need someone to run it through Quick load to see what that says.

I’m just using Fed 210 match primers.
 
I honestly can’t tell you with certainty. I know that I’m using a suppressor and see zero evidence of left over powder in my 30” barrel, but you’ll need someone to run it through Quick load to see what that says.

I’m just using Fed 210 match primers.
I did run it through GRT (Gordons Reloading Tool), and it gave me this:
 

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If a certain powder/load gave you top velocity, good accuracy and SD, I'm having a hard time fathoming why anyone would care what a computer model says the % powder burn is? Seems like a meaningless metric.

I've done load development or velocity testing with Staball HD, H1000, H4841SC, RL-26 and Grand in my 19" PRC, Grand gave the best velocities and good accuracy, if Quickload said the powder burn in my barrel was only 10%, it wouldn't make a difference in how it performs.
 
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If a certain powder/load gave you top velocity, good accuracy and SD, I'm having a hard time fathoming why anyone would care what a computer model says the % powder burn is? Seems like a meaningless metric.

I've done load development or velocity testing with Staball HD, H1000, H4841SC, RL-26 and Grand in my 19" PRC, Grand gave the best velocities and good accuracy, if Quickload said the powder burn in my barrel was only 10%, it wouldn't make a difference in how it performs.




You’re missing one thing based on what you said, and that’s consistency. So you mean to tell me if you run a powder with a slow burn rate that will not provide you shot for shot 100% burn propellant that is doesn’t make a difference on how it performs?

So if your running a slow burning powder and your not getting 100% burn propellant, then after that primer ignites, and creates combustion, then the gas outflow velocity is roughly 400-500fps faster than your muzzle velocity and unburnt kernels of powder are shot blasting the back of your projectile, you call that consistent? I don’t think so.

As reloaders we all have different demands etc… with that being said, if punching one hole @ 100 yards is what you demand and nothing else matters, that’s fine but not for me. I want 100% burnt propellant, SD below 8, ES below 18, & .50” consistency @ 100 yards, & less than 10” of vertical dispersion @ 1000 yards. If it doesn’t have these things listed in check, I’m not interested.
 
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You’re missing one thing based on what you said, and that’s consistency. So you mean to tell me if you run a powder with a slow burn rate that will not provide you shot for shot 100% burn propellant that is doesn’t make a difference on how it performs?

So if your running a slow burning powder and your not getting 100% burn propellant, then after that primer ignites, and creates combustion, then the gas outflow velocity is roughly 400-500fps faster than your muzzle velocity and unburnt kernels of powder are shot blasting the back of your projectile, you call that consistent? I don’t think so.

As reloaders we all have different demands etc… with that being said, if punching one hole @ 100 yards is what you demand and nothing else matters, that’s fine but not for me. I want 100% burnt propellant, SD below 8, ES below 18, & .50” consistency @ 100 yards, & less than 10” of vertical dispersion @ 1000 yards. If it doesn’t have these things listed in check, I’m not interested.
I said a load that "gave you top velocity, good accuracy and SD" , not ignoring consistency. My point is you're going around your ass to get to your elbow focusing on a model's prediction of % powder burn to guess at consistency (questionable assumption at best) when you can actually shoot and take real data. It doesn't make any sense to get preoccupied with that string of guesses and assumptions, shoot and see what reality looks like
 
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I said a load that "gave you top velocity, good accuracy and SD" , not ignoring consistency. My point is you're going around your ass to get to your elbow focusing on a model's prediction of % powder burn to guess at consistency (questionable assumption at best) when you can actually shoot and take real data. It doesn't make any sense to get preoccupied with that string of guesses and assumptions, shoot and see what reality looks like


It does when you’re saving components, and that’s the whole purpose.
 
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22” Carbon Six. 80-85 degrees outside. 900 ft altitude.

Peterson, GM215M, Berger 175 EH, N570

5 shot group - 73.7gr - 3107 avg , 6.5 SD, 18.4 ES

For comparison, I got 2871 fps avg from factory Hornady ELD-X on the same day.
For some reason the published VV load data is waaaay conservative in this caliber.
 
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Berger's load data states a max of 75.1 gr of N570 using Hornady brass.
That’s wild. VV load data says max 66.5 and that’s its compressed at that charge which clearly isn’t. Those are almost 7Saum numbers.
QL also shows their max load at barely 50K psi.
Not sure how VV came to their loads and I wonder if someone used a different case capacity.
 
It does when you’re saving components, and that’s the whole purpose.
Theres nothing wrong about trying different components to experiment. Not sure I'd try to call that "saving components," though. H1000 looks like a solid load, if it checks out at 1k. If it was me, I'd be taking the best load of those and load up 20. Retest for a 10rd group at 100 for chrony data and group size with an actual statistical number, then if it looks good on paper and chrony, use the next 10rds to watermark load at 1k.
 
Theres nothing wrong about trying different components to experiment. Not sure I'd try to call that "saving components," though. H1000 looks like a solid load, if it checks out at 1k. If it was me, I'd be taking the best load of those and load up 20. Retest for a 10rd group at 100 for chrony data and group size with an actual statistical number, then if it looks good on paper and chrony, use the next 10rds to watermark load at 1k.
Those are are x3 shot groups I shot only once, and after retesting them they did not repeat, nor have acceptable ES & SD. You can't assume these are loads based off of these groups / small sample sizes.

Also as to your statement about not saving components, using Quickload / GRT would definitely help anyone save components if you understand, and know how to use it. My statement about "savings components" was directed towards this, not about switching powders.
 
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Those are are x3 shot groups I shot only once, and after retesting them they did not repeat, nor have acceptable ES & SD. You can't assume these are loads based off of these groups / small sample sizes.

Also as to your statement about not saving components, using Quickload / GRT would definitely help anyone save components if you understand, and know how to use it. My statement about "savings components" was directed towards this, not about switching powders.
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.