itsthemann
Active Member
So what's different dimensionally regarding +P chambers? I've been reading a few posts regarding people and their +P 300PRCs and whatnot, just curious what the actual difference is. Is it just more freebore?
+P Chambers
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Wachsmann
Well-Known Member
Well that is a tough question. I think the original person that introduced it may have patented it so it's probably trade knowledge for the exact specifications but in a nut shell what I understand about it is optimum freebore at an angular approach to the lands. Biggest thing it works great for what I've read about as for as pressure and velocity numbers that you get.
Wachsmann
Well-Known Member
100% agree. That's the man. He is the one I was trying to think of.
Actually it was Roy Weatherby. I'm not taking away from Shawn by any means at all. He just improved on it. Roy did it with free bore, Shawn did it with a reamer. It will be very interesting to see what the future will hold with the velocity gaining smiths in the future. Ackley, Allen, is another in velocity gaining cartridge's, every single one of them has put a stamp on innovation and a continuous innovation on changing the design and improvement in load and rifle development. Bless these innovations in the industry.
Shawn is also smart enough to take advantage of coming up with the .338 Edge, which is what a .338 RUM should have been. It is a missed opportunity for Remington and an opportunity for Shawn to capitalize with excellent success.
Agreed! Amen to the innovators in the gun, shooting, and hunting industries.
tracybartlein
Active Member
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A word to the wise....
by lengthening the throat and opening up the diameter.... it will work against you barrel life wise from everything we've seen. I/we will not warranty any barrel from a claim that the barrel died early, and you stuffed a +P reamer into the chamber/barrel.
For a hunting gun and you only put say 20ish rounds thru it in a year... knock your socks off but if your intent is to get another 100 or 200fps out of the cartridge and you want to run it hard off the bench or in matches... there are no free lunches as the saying goes. Your going to pay for it somewhere.
Later, Frank
Bartlein Barrels
by lengthening the throat and opening up the diameter.... it will work against you barrel life wise from everything we've seen. I/we will not warranty any barrel from a claim that the barrel died early, and you stuffed a +P reamer into the chamber/barrel.
For a hunting gun and you only put say 20ish rounds thru it in a year... knock your socks off but if your intent is to get another 100 or 200fps out of the cartridge and you want to run it hard off the bench or in matches... there are no free lunches as the saying goes. Your going to pay for it somewhere.
Later, Frank
Bartlein Barrels
To add to the above post; free bore, straightening cartridge walls, 40 degree shoulders all helped improve cartridge design, but to a large degree, the extra velocity came because they added more powder to the same loads. For Ackley and Weatherby chamberings this is particularly true, and also true for +P. More powder means more speed but also faster barrel wear for sure, and the more overbore the cartridge the more this is accelerated. Yes you get more velocity but as Frank rightly said, you are paying for it in accelerated wear and higher component use.
If you are worried about short barrel life if you go the +P route, let me know and let you keep in touch of peeps that have no issues with it.
tracybartlein
Active Member
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Well said Dean2! Also add in they're the type of powder.... some powder types burn at a higher flame temperature and that will work against you as well.
Also, I have not seen a shred of evidence from actual pressure testing done with an ammunition pressure test barrel to tell you what you reliably get out of a given cartridge velocity wise and staying with in normal pressure limits and its effect on barrel life. To me there isn't any hard data anywhere.
A guy takes a 300RUM which already in a perfect world has a barrel life that's less than a 1k rounds (probably around 700ish tops) and then you lengthen the throat and make the free bore diameter bigger so you can dump another 5gr of powder down it to pick up another 100fps or so.... you have to ask yourself... is another 100ish fps faster worth anything in the grand scheme of things in the long run?
If you want to get more speed out of an existing rifle and still have cartridges fit the mag the +p is a great low cost option.
And the 300 and 338 Terminators with +p throats are no joke - they flat out perform. I have a 338-378 wbee and my 338 Terminator kicks its tail.
And the 300 and 338 Terminators with +p throats are no joke - they flat out perform. I have a 338-378 wbee and my 338 Terminator kicks its tail.
