7mm prc, how short is too short?

[WKR]

Im shooting a 20” 7prc I ran a pressure test with H1000 I barely found pressure signs before hitting a compressed load. Im shooting at 2850 with 180 eldms

I only have 30rds thru the barrel so im sure it’ll speed up. Possibly 2875-2900 but my goal was to atleast break 2850. That does everything I want out of the rifle and I have 9lbs of H1000 so I probably won’t test too many other powders.


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Accuracy?

 

[Cbthomas]

Accuracy?

I will know more Saturday. I was rushing to get the 6shot group in because the sun had already set and I was shooting off a terrible rest.

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[WKR]

I will know more Saturday. I was rushing to get the 6shot group in because the sun had already set and I was shooting off a terrible rest.

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Sammi chamber? 70 gr sounds pretty high pressure

 

[Cbthomas]

Sammi chamber? 70 gr sounds pretty high pressure

Yes Sammi spec, it’s a carbon6 prefit. I thought about doing the +P throat but I would have to find a faster powder.

Hornady says min/max for 180s with h1000 is 59.8-67.4

I started at 63.5 and went to 69g and did not see any signs of the classic pressure signs. So then did a lift up to 70.5 with was basically 100% case capacity, if not starting to be compressed. 70.5g was the first sign of any ejector marks on the case head, primer still looks good and bolt lift was the same throughout the entire pressure test.

Obviously, this is well above book max approach at your own risk.

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[TEWONG]

Yes Sammi spec, it’s a carbon6 prefit. I thought about doing the +P throat but I would have to find a faster powder.

Hornady says min/max for 180s with h1000 is 59.8-67.4

I started at 63.5 and went to 69g and did not see any signs of the classic pressure signs. So then did a lift up to 70.5 with was basically 100% case capacity, if not starting to be compressed. 70.5g was the first sign of any ejector marks on the case head, primer still looks good and bolt lift was the same throughout the entire pressure test.

Obviously, this is well above book max approach at your own risk.

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Similar results for me. No pressure signs using 70gr H1000 + 180gr Berger Hybrids + ADG brass. Getting 2975fps out of a 20" Proof barrel chambered by Sterling Precision.

 

[Cbthomas]

Similar results for me. No pressure signs using 70gr H1000 + 180gr Berger Hybrids + ADG brass. Getting 2975fps out of a 20" Proof barrel chambered by Sterling Precision.

That’s smoking! I have about 50 rds down the tube. My last 10 shot average was 2871.


What’s your round count and what what primers are you using?


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[TEWONG]

That’s smoking! I have about 50 rds down the tube. My last 10 shot average was 2871.


What’s your round count and what what primers are you using?


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Close to 150rnds. Using Federal 215 Match primers. I'm sure someone out there is going to call BS on the velocity but data was confirmed via Labradar and drops out to 1000yds.

 

[WKR]

Similar results for me. No pressure signs using 70gr H1000 + 180gr Berger Hybrids + ADG brass. Getting 2975fps out of a 20" Proof barrel chambered by Sterling Precision.

Whats your coal? How far off the lands?

 

[TEWONG]

Whats your coal? How far off the lands?

2.632" Ogive to base. 3.375" Tip to base. .025" off the lands.

 

[WKR]

2.632" Ogive to base. .025" off the lands.

Internal mag or dbm?

 

[TEWONG]

Internal mag or dbm?

DBM

 

[WKR]

DBM

Nice I've got a very similar build with the same chassis but a vampire action and carbon IBI barrel. Topped with the same atacr.
Are you using the Accurate 300 rum magazines?

Edit: couldn't get the scope any lower with lower rings?

 

[TEWONG]

Nice I've got a very similar build with the same chassis but a vampire action and carbon IBI barrel. Topped with the same atacr.
Are you using the Accurate 300 rum magazines?

Edit: couldn't get the scope any lower with lower rings?

Using AICS 300 Win Mag 3.850" magazine. Rings (Hawkins medium) are what I had on hand from a previous build so living with the scope height for now...

 

[Cbthomas]

Close to 150rnds. Using Federal 215 Match primers. I'm sure someone out there is going to call BS on the velocity but data was confirmed via Labradar and drops out to 1000yds.

Only the guys shooting factory ammo will call bs.

Typically see 75-100fps speed up after 100ish rounds

So that will put me between 2925-2950fps

I shooting federal 210M’s just because I have a bunch and can’t fine 215’s


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[Marty]

I think you’re fine. I went with an 18” and expect to hit 1800 fps (which is considered minimum velocity for expansion for the bullets I plan to use) out around 800 yards with various bullets at the altitudes I plan to hunt at.I

I think you’re fine. I went with an 18” and expect to hit 1800 fps (which is considered minimum velocity for expansion for the bullets I plan to use) out around 800 yards with various bullets at the altitudes I plan to hunt at.

Nice, I also went an 18" Bartlein carbon barrel for my 7mm PRC

 

[gtriple]

Yes, they don’t have the BC of say a eldx bullet.

no, they were his bullets and he used my Hornady brass because of the difficulty getting brass for the 7PRC right now.. I can put you in touch with him if you would like

Could you PM me his contact info? Just got my 7prc and want to get the load developed for it.

 

[donrleonard]

I think you’re fine. I went with an 18” and expect to hit 1800 fps (which is considered minimum velocity for expansion for the bullets I plan to use) out around 800 yards with various bullets at the altitudes I plan to hunt at.

Curious if you run into any kind of muzzle blast from unburnt powder at 18”. I’ve got a Browning XBolt in 7PRC that I’m thinking of having chopped down to 18, but I don’t plan to run a suppressor.

 

[donrleonard]

Nice, I also went an 18" Bartlein carbon barrel for my 7mm PRC

Any issues with muzzle blast from unburnt powder?

 

[TxLite]

Curious if you run into any kind of muzzle blast from unburnt powder at 18”. I’ve got a Browning XBolt in 7PRC that I’m thinking of having chopped down to 18, but I don’t plan to run a suppressor.

It’s never been shot without a suppressor but I’ve never taken the suppressor off and found unburnt powder like I do with my 300blk. I’ve also never seen any flash when shooting at dusk.

 

[donrleonard]

It’s never been shot without a suppressor but I’ve never taken the suppressor off and found unburnt powder like I do with my 300blk. I’ve also never seen any flash when shooting at dusk.

That’s exciting. I appreciate the field report!

I’ve been shooting 160gr Hornady CXs, which I think are loaded a bit light as they have the same posted muzzle velocity (3000fps) as their 175gr ELDX. Makes me think they’d shoot well out of a shorter barrel…