7mm-300 PRC

Orange Dust

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Oct 23, 2015
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Look how the .300 PRC performs above the .300 WM. It can give you a rough idea of what to expect above the 7RM.

There is a fella called "Aaron Hipp" on FB that has a 28" barreled, 7-300 PRC. He said he can push 180's to 3300.
Yes, Load it hot and you just invented the STW. I think it would be cool in 27cal with the new EOL's.
 

Wlfdg

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Bigeclipse

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I have a Howa 1500 7mm RemMag that I'm looking to rebarrel.
I have an interest in the 7mm-300 PRC.
It would be my first time rebarrelling an action.
First time necking down brass and loading a wildcat cartridge.

Does anyone have experience with this cartridge?
Pros? Cons?

I have a 300WM that is by far my favorite elk rifle.
The Howa is really about the experience.
a rumor is going around there will be a 7PRC which will be based off the 300prc case. Maybe wait for that?
 

JMGamesniper19

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I am currently building a 7mm/300 PRC as we speak. Why? I believe the following to be true and will get a chance to pressure test my theory here in about 8-12 weeks :)
  • I am luck to own many LR custom rifles so right off the bat, I am spoiled and admit it but hey MERICA!
  • I want a lighter weight backcountry hammer for N American game at longer ranges out west where I live. Yeah I have 300's that will do it all day but I believe the 7mm is hitting a sweet spot with efficient ballistics without having to push 225 grain bullets
  • I have a 13 lb 7mm/300 Norma Ackley that is awesome but a handful to shoot and will have <800 rounds of barrel life. Also very component critical - pushes the 195 eol at 3190 without a problem and could probably hit 3300.
  • Taking the current 300 PRC case and necking to a 7mm will be highly efficient - more efficient than 28 Nosler with equal ballistic results and i hope a bit more barrel life - should get 3100 without too much issue
  • Not changing anything but the neck size so all the attributes and chamber measurements from the PRC are utilized - may get a tiny bit more neck length
  • Not really a wildcat - i can use 300 PRC S series die set with a 314 or 316 bushing (ill know when I load my first round) 300 PRC brass - premium brass from peterson, copper creek or others should be out after SHOT show
  • Reloading data should be similar to the 300 PRC with 180/200 grain bullets - and using the 195 eol or even the 180 ELDX should be quick to find a load
Building with a gunsmith that already has a 7mm 300 dakota and we both agreed that this set up will be better for many reasons listed and perhaps a few more. configuration will be directed to hunting and will include

BAT HR LA action
PROOF sendero 24" barrel - 8.44 twist
AG composite Alpine Adj stock
Timney calvin elite 2lb trigger
Kahles K624i scope
 
Last edited:

JMGamesniper19

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UPDATE
Rifle is done and i have gone through barrel break in and my first ladder. Results so far:
All results are with Hornady 175 ELDX bullets, cci 250 primers, and RL 25 powder. Hornady 300 PRC data for 175 eldx states that 83.7 is the max load so I decided to start 5% below and go up. I like to run PROOF barrels hot. They seem to like it in my other PROOF barreled rifles.
  1. Laddered multiple charges 79.5 - 79.8 - 80 - 80.3 - 80.6 and started seeing pressure at 81.0 so I stopped there. Decided to go with 80.3 which Magneto speed chrono showed at 3240 with around 12 FPS SD's (this should get better after firing all the brass and sizing to chamber)
  2. Experimented with jumps starting at .010 down to .002 and found that at anything closer than .004 started to show pressure
  3. Shot a couple 5 shot groups with 80.3 RL25 with .006 jump and got two sub 1/2 MOA groups (better group was .36) at 3241 FPS avg - no real pressure issues, maybe a tiny bit of extractor marks (I mean tiny if you look really hard under good light) using Hornady brass I am ok with that
So far I have 35 rounds through the rifle and with the PROOF barrel I expect it to get a bit better as I reach 60 in round count. At 60 is where my other PROOF rifles start to really group and it may pick up 10-15 FPS speed as well.

So far pretty happy. Dont think I would run a bullet bigger than the 175 in this rifle. Why? it is already seating pretty deep into the case. If you do want to run the 195 berger you may want more free bore to accommodate (I built a 7-338 Norma so I could run the 195 berger to max velocities) It was my choice to optimize this 8.44 twist rifle purely for hunting using the 175 eldx - I wanted max speed and so far it is meeting expectations.
 

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elkaholic

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UPDATE
Rifle is done and i have gone through barrel break in and my first ladder. Results so far:
All results are with Hornady 175 ELDX bullets, cci 250 primers, and RL 25 powder. Hornady 300 PRC data for 175 eldx states that 83.7 is the max load so I decided to start 5% below and go up. I like to run PROOF barrels hot. They seem to like it in my other PROOF barreled rifles.
  1. Laddered multiple charges 79.5 - 79.8 - 80 - 80.3 - 80.6 and started seeing pressure at 81.0 so I stopped there. Decided to go with 80.3 which Magneto speed chrono showed at 3240 with around 12 FPS SD's (this should get better after firing all the brass and sizing to chamber)
  2. Experimented with jumps starting at .010 down to .002 and found that at anything closer than .004 started to show pressure
  3. Shot a couple 5 shot groups with 80.3 RL25 with .006 jump and got two sub 1/2 MOA groups (better group was .36) at 3241 FPS avg - no real pressure issues, maybe a tiny bit of extractor marks (I mean tiny if you look really hard under good light) using Hornady brass I am ok with that
So far I have 35 rounds through the rifle and with the PROOF barrel I expect it to get a bit better as I reach 60 in round count. At 60 is where my other PROOF rifles start to really group and it may pick up 10-15 FPS speed as well.

So far pretty happy. Dont think I would run a bullet bigger than the 175 in this rifle. Why? it is already seating pretty deep into the case. If you do want to run the 195 berger you may want more free bore to accommodate (I built a 7-338 Norma so I could run the 195 berger to max velocities) It was my choice to optimize this 8.44 twist rifle purely for hunting using the 175 eldx - I wanted max speed and so far it is meeting expectations.
nice build!
 

JMGamesniper19

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Feb 16, 2016
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Update: Official caliber name is the 7mm GARRETT. It is complete.
After testing and working through the calibration of the free bore and powder cocktails, we feel like we have the caliber in a great place. What we accomplished:
  1. Calibrated freebore and landed at .240. That freebore is optimized for the 175 eldx and will not run the 195 berger; it wont fit in the BDL style mag.
  2. By adding freebore we eliminated the pressure spike at 81 grains. We also dropped our FPS slightly and landed at 3210 fps with 81.0 grains of RL25. Very happy with that node.
  3. Seeing consistent sub 1/2 groups with best group at .29 running jump .012 off the lands - will probably leave it right there. This is 100% a hunting rifle
In my opinion this rifle is equal to or perhaps even better than the 28 Nosler. It runs just as fast, has better case dimensions and powder efficiency and is plenty fast enough for ANY application. I wonder why Hornady marketing hasn't gone down this road yet but no matter, we did and we LOVE IT!!
 

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