+P chambers

Status
Not open for further replies.
Question from the less infromed, Why is called +P chamber, when the objective is to have the same or lower pressure, but higher velocity?
You tell me! My guess is the guy that dreamed it up... it was his brain child so he had to put a name on it.

It also confuses shooters as well. They think they are loading +P ammo but that's not the case. This isn't the same as +P pistol ammo. The +P pistol ammo is loaded to a higher pressure and hence forth higher velocities. That's why they say some pistols shouldn't be shot with +P ammo as they guns are not rated for the pressure/safety issues.

The +P ammo is still being used in a standard spec chamber. They are not modifying the throat at all.
 
You tell me! My guess is the guy that dreamed it up... it was his brain child so he had to put a name on it.

It also confuses shooters as well. They think they are loading +P ammo but that's not the case. This isn't the same as +P pistol ammo. The +P pistol ammo is loaded to a higher pressure and hence forth higher velocities. That's why they say some pistols shouldn't be shot with +P ammo as they guns are not rated for the pressure/safety issues.
That is why it was confusing to me and I had to ask. I used to shoot +P 9mm ammo, which is "hot" and made no sense to call this champers +P.
I am not even an amateur when it comes to ballistics (interior) but I think Roy Weatherby did a complete package (case, throat, action) close to 80 years ago.
I also agree with your comparison to engines. You can go really really fast, a couple of times, or you can go normal speeds for a lifetime
 
That is why it was confusing to me and I had to ask. I used to shoot +P 9mm ammo, which is "hot" and made no sense to call this champers +P.
I am not even an amateur when it comes to ballistics (interior) but I think Roy Weatherby did a complete package (case, throat, action) close to 80 years ago.
I also agree with your comparison to engines. You can go really really fast, a couple of times, or you can go normal speeds for a lifetime
+p in pistols is way different than in rifles (exceptions, 257rob and similar). Pistol +p has increase in case pressure as +p throating has a faux lead that let's you (within reason, say 100% case fill) use a faster powder to achieve the extra speed. It's the Vang comp for rifles.
 
DE's +P value is going to be an individual perspective thing. Not a good fit for high volume shooters but some possible advantages for long range hunting rigs running very low mileage. I agree it is only fair for a barrel manufacturer to withdraw warranty on mods like this.

The idea is to help ease the long heavy bullets into rotation at higher velocity without excessive stress on the jacket from deep land engraving. Possible velocity gains of +/- 150 fps. It offers performance gains but typically significant loss of accuracy life. It's not possible to easily set the barrel back to clean up the throats if needed, and the lands of the rifle in much of the throat length is quite shallow compared to the conventional height of lands.
 
+p in pistols is way different than in rifles (exceptions, 257rob and similar). Pistol +p has increase in case pressure as +p throating has a faux lead that let's you (within reason, say 100% case fill) use a faster powder to achieve the extra speed. It's the Vang comp for rifles.
The point I was trying to make with my limited understand of what they call +P in rifles, it is a misnomer. In pistols, it is higher pressure, in rifles at best it could be called +V
The .277 FURY by Sig, is a true "+P" in my mind. 80k psi or something?
I am glad the OP posted this thread, forced me to learn something new
 
Status
Not open for further replies.

Recent Posts

Top