7-6.5PRCW

[FrankG]

What are the differences between a P&V barrel and an accuracy one that have the most influence on accuracy?
Thank You

A P&V barrel (pressure and velocity) has a threaded pressure port in it. The port into the chamber is .250” in diameter and the port is .175” behind the shoulder. So the brass will push against the sensor to give the pressure reading. I think this is the reason whey it can effect the accuracy a little.

A straight up velocity test barrel or a test barrel in an accuracy rig eliminates this. Some accuracy test barrels are just 1.250” straight usually and sit in a rail gun type fixture.

 

[FrankG]

What are the differences between a P&V barrel and an accuracy one that have the most influence on accuracy?
Thank You

Some pic's might help....







The middle pic is what a universal test receiver looks like. It's basically a cannon breech type system. You unscrew the ring with the 3 round balls on it... slide the p&v barrel into the receiver. That ring then slides on over the muzzle and you tighten it up against the front shoulder/collar on the breech end of the barrel. That's what holds it into the receiver. On the test barrel pic. you can see the the threaded pressure port. That front hole doesn't go all the way thru into the barrel. It's a blind locating pin hole.

 

[J Fess]

Thank you. I had seen P&V setups but not an accuracy test rig. At least, not a modern one ( I had read Dr. Mann's 1909 book and seen the older Mann Accuracy Device with its V-shaped trough). I wondered if the accuracy was an artifact of the barrel profiles used, Universal Receiver, or pressure measuring setup. Upon looking at the photos, I could see how the barrel clamp alone could reduce barrel vibrations in the accuracy test setup. The answer, as usual, seems to be "It's Complicated".

 

[FrankG]

Thank you. I had seen P&V setups but not an accuracy test rig. At least, not a modern one ( I had read Dr. Mann's 1909 book and seen the older Mann Accuracy Device with its V-shaped trough). I wondered if the accuracy was an artifact of the barrel profiles used, Universal Receiver, or pressure measuring setup. Upon looking at the photos, I could see how the barrel clamp alone could reduce barrel vibrations in the accuracy test setup. The answer, as usual, seems to be "It's Complicated".

Believe it or not there are places that still use the v block rest type set up. The barrel has specific dimensions and tolerances.

Here is a pic of another version of an accuracy barrel....That front large diameter shoulder is 1.750" and basically butts up against the v block rest. The action just floats out in the wind. They set the trigger sear engagement so the firing pin will not be held back when the bolt closes. They heat the bolt handle up and basically bend it up to a 90 degree angle. So they drop a round into the loading port and close the bolt and as soon as the bolt is closed it goes bang. The shooter never removes his hand from the bolt and opens it right away. I forget the time frame they have to get off like 10 or 30 rounds in. Windspeeds cannot be over I think it was 6mph????? and all accuracy data for this particular set up is recorded at 600 yards. They do other testing at 100 and 200 as well.

 

[FrankG]

Jeff here in the shop laid his hands on some RL16. So I loaded up some loads with RL16 and shipped them out the other day so they can be included in the pressure and velocity testing for data.

Later, Frank
Bartlein Barrels

 

[nwmnbowhunter]

Anyone have the COAL with 180 hybrids to lands?

 

[Airborne-350G]

Anyone have the COAL with 180 hybrids to lands?

Wouldn’t that be different for different freebores?

 

[Sandstorm]

Wouldn’t that be different

They all be different Sir. Ya gotta measure your own chamber.

 

[nwmnbowhunter]

Just looking for approximate using wheelers reamer

 

[Airborne-350G]

Just looking for approximate using wheelers reamer

Can post mine when later today. Mine is based on Wheelers reamer.

 

[ABC1000]

I am getting a lot of calls and emails about this so Im going to start a thread to answer them here.
The 7-6.5prcw is simply a necked up 6.5 prc. The base diameter is corrected to prevent clickers. Thats all thats different about the case body.
What is different is my throat. The lead angle and diameter.
No, my reamer is not available to the public. No, I wont tell you about the throat. But if you guys want I can spec one out with the typical 1.5 degree lead and release it through jgs. Erik has already done that through Manson. Those reamers will shoot.
Dies are easy. Bullet central makes a sizer or you can open the neck in a 6.5 prc die and use a 7mm bushing. Seaters are reamed wilson blanks.
All the same powders and primers you run in the 284 work.
Yes, you will need to order a magnum bolt for your action.
I have a shop reamer and order reamers for customers that want to own their own for me to chamber their barrels with.

Hey Alex, I’ve got my complete 7-6.5 PRCW

I was told I could let the cat out of the bag. We have ADG brass that you can shoot right out of the box now. I was told the first real run will happen this winter. I sent some to Tim Vaught, hes currently shooting some.

anybody have a bushing size recommendation to start out with on Alex’s 7-6.5 PRCW with micron ideas and ADG 7-6.5 brass? This will be my first dive with Micron dies. I’m on the road through next week and my rifle should be showing up next week. I also have several boxes of Lapua to size up. Went with Alex’s no turn chamber

 

[Airborne-350G]

I would order a .312 and a .310 bushings. When brass usually thins to 0.014 neck wall thickness. So a seated bullet with that thickness should be .312. But I don’t just rely on neck bushings. I use a mandrel to make the inner dimensions the same around and to set my seating pressure. Most times the necks will not be uniformed all the way around after expanding.

 

[Sandstorm]

For ADG im using SAC dies and a .308 bushing.. youl need to check your sizing however..

 

[ABC1000]

I would order a .312 and a .310 bushings. When brass usually thins to 0.014 neck wall thickness. So a seated bullet with that thickness should be .312. But I don’t just rely on neck bushings. I use a mandrel to make the inner dimensions the same around and to set my seating pressure. Most times the necks will not be uniformed all the way around after expanding.

Thanks I have mandrel as well but am just looking for something close in the micron die. Thanks again

 

[ABC1000]

For ADG im using SAC dies and a .308 bushing.. youl need to check your sizing however..

Thanks

 

[ABC1000]

Unless I’m reading it wrong, it looks like the Micron dies are compatible with my Redding bushings so I should have all o need. Thanks for the help. Aaron

 

[Alex Wheeler]

Yes the Micron works well with my chamber

 

[Dave M.]

You need a 900 number.

If anyone cares, you can order my print. I followed Wheeler's suggestion on the base dimensions and Dr Tooley's advice on the freebore diameter. Standard lead angles.

View attachment 1425647

What is the trim to length for your brass? And max brass case length prior to trimming?
Dave

 

[G7BC]

What is the trim to length for your brass? And max brass case length prior to trimming?
Dave

2.020 is good. Mine are set to 2.015 because it works better to get them all consistent on my initial trim after necking up and turning new Lapua. Have been running that trim length since the start and it works well. I do and would recommend to trim every firing on a Giruad for consistency so don't worry about what max is.

 

[WeatherbyFan]

Hey Alex, I’ve got my complete 7-6.5 PRCW

anybody have a bushing size recommendation to start out with on Alex’s 7-6.5 PRCW with micron ideas and ADG 7-6.5 brass? This will be my first dive with Micron dies. I’m on the road through next week and my rifle should be showing up next week. I also have several boxes of Lapua to size up. Went with Alex’s no turn chamber

I just measured the necks of 10 loaded rounds with ADG 7-6.5 PRCW brass and 168 Bergers
.311” was same measurement on every round, one bounced between .310.5” and .311”