Thread: Short barreled 7prc

Makes a lot of sence.

Gotta get used to the fact that factory ammo now a days are actually pretty good.

Originally Posted by Kelton

I think it gets to a point of diminishing returns with the bigger case in short barrels the short fat powder cases seem to do better

Im of the general view that its all case capacity, pressure, and effective barrel length. Whenever I run GRT on similar capacity cases if i add the extra length to the long action they preform the same. ie a 7saum has more rifling in the same length barrel as a 280AI they share pretty much the same powder capacity. The SAUM effectively has an extra half inch or so of rifling (ie a longer runway and longer time for gas to exert pressure. This is about equivalent to the performance differences.

Your right everything is diminishing returns really.

So random thoughts that I've had because I dont want a long rifle ie no longer than 18" on a short action:
-A short action means the total package length can be shortened to also allow a longer barrel for same total firearm length leading to exaggerated differences.
-A smaller diameter case exerts less bolt thrust for the same pressure ie when talking action strength its safer to run a 308 case head hotter than a wsm case head (like safer to run the 308 at 75kpsi that a wsm at saami)
-Higher pressure helps powder burn and more powder actually leads to a higher burn in the same case. It also needs less powder for the speed so recoil is often lower than running a bigger case at lower pressure. Good brass can handle this pressure.

I'd wait for 7mm backcountry, it's for this exact problem. Either get one of them or get a used chopped down 7PRC that has tanked in value

Originally Posted by Jaco Goosen

I was thinking the exact thing Lars.

Also extremely over pressure so wouldn’t be recommending those figures

Surely youd be able to push 180s at 2800? Can't think of anything you couldn't do with that in about any nz hunting scenario out to way further that we should be shooting animals.

Originally Posted by Stocky

Im of the general view that its all case capacity, pressure, and effective barrel length. Whenever I run GRT on similar capacity cases if i add the extra length to the long action they preform the same. ie a 7saum has more rifling in the same length barrel as a 280AI they share pretty much the same powder capacity. The SAUM effectively has an extra half inch or so of rifling (ie a longer runway and longer time for gas to exert pressure. This is about equivalent to the performance differences.

Your right everything is diminishing returns really.

So random thoughts that I've had because I dont want a long rifle ie no longer than 18" on a short action:
-A short action means the total package length can be shortened to also allow a longer barrel for same total firearm length leading to exaggerated differences.
-A smaller diameter case exerts less bolt thrust for the same pressure ie when talking action strength its safer to run a 308 case head hotter than a wsm case head (like safer to run the 308 at 75kpsi that a wsm at saami)
-Higher pressure helps powder burn and more powder actually leads to a higher burn in the same case. It also needs less powder for the speed so recoil is often lower than running a bigger case at lower pressure. Good brass can handle this pressure.

Just off my limited experience the short fats don’t seem to suffer as much I here you on the rifling my direct comparison is 7 blazer mag 7prc and 7 saum the 280akley certainly suffers in a short barrel even if you allow the extra inch of rifling

And 7LRM sorry you seem to end up about 40-50fps faster with 7 grains more powder in those bigger cases I’m all for the factory ammo though and wouldn’t hesitate to run a 20” prc because I’m not expecting miracles hell if it was 2700 accurate and factory ammo I’d be happy

Originally Posted by Kelton

Just off my limited experience the short fats don’t seem to suffer as much I here you on the rifling my direct comparison is 7 blazer mag 7prc and 7 saum the 280akley certainly suffers in a short barrel even if you allow the extra inch of rifling

Without accurate pressure testing equipment our experience means nothing really when we are talking this small a nuance and have no idea what our pressures accurately are. Even assuming same brass manufacturer it can vary case to case. 280AI is often loaded in softer Norma or Nosler Brass where most reload Saum with ADG etc nowadays. GRT has them at the same pressure (65kpsi) same powder (RL26) same bullet (180 ELD) within 13fps of each other with a 20 inch barrel. If you add the extra 0.5inchs of barrel to the 280 so the projectile path distance matchs the 280 is slightly ahead (like 5fps) due to having marginally more case capacity. Id take that as more reliable that guessing based on cases. Otherwise basing it on that 280ai in a 20 inch barrel outperforms the 7mm Rem Mag bit i know its likely due to brass quality and the pressures i was running.

Regardless its immaterial as even a high BC 7mm has lost a 100fps well within 100yards.

7mprc should have good component supply id be happy to run it 7SAUM,280ai, or any of the other bigger 7s id want to already own the brass.

I used to love the big 7s and think there's still something awesome about them but they are so far beyond what's required to kill out to any range we can do that I gave up chasing them. One day I might get a wild urge to build something stupid like a 7NMI just because.

20inch Bartlett, fed 215, 68.5 grain re26, 175 Berger elite hunter, adg brass doing 2980 fps. No sticky bolt lift, flattish primers but no cratering.

20inch bartlein*

66gn of rl26 is bang on 65k psi in GRT for a 24in barrel you are way overpressure

Interesting replies cheers guys, I just had an itch n seeing if anyone would scratch it

I have owned a 7prc 22" & now running a 270wsm with a 18" found that ADI powders ( while good accuracy ) were a bit gutless, RL26 is definitely the bizzo

Ye mighty 270wsm is running 140BT's @ 3050 now

Originally Posted by Philipo

Interesting replies cheers guys, I just had an itch n seeing if anyone would scratch it

I have owned a 7prc 22" & now running a 270wsm with a 18" found that ADI powders ( while good accuracy ) were a bit gutless, RL26 is definitely the bizzo

Ye mighty 270wsm is running 140BT's @ 3050 now

Perfect projectile for that chambering, from light thin skinned game to the heaviest of stags.

Originally Posted by Philipo

Interesting replies cheers guys, I just had an itch n seeing if anyone would scratch it

I have owned a 7prc 22" & now running a 270wsm with a 18" found that ADI powders ( while good accuracy ) were a bit gutless, RL26 is definitely the bizzo

Ye mighty 270wsm is running 140BT's @ 3050 now

Browning Xbolt 140 Nosler BT 70 grains of IMR 7977. I'm pretty sure it's a 22-inch, though. Anyway, not much is going to walk away from your load.

Originally Posted by 7mmsaum

Perfect projectile for that chambering, from light thin skinned game to the heaviest of stags.

Or just the bark off some totara trees in phils case.

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