7PRC AW spec reamer?

[prcwv]

This has been my experience

 

[Mcranch]

I posted on another 7 prc page concerning ram powder I think that was the topic, anyway I listened to a Ron Spomer interview with a rep from Hornady. The rep was stating that the powders have not been consistent in the amount or quality and that sloppy chambers don't allow for better velocity. That is why the numbers on their factory loads are off (?). Concerning chamber specs I will get with JGS. My question is stay with the saami neck or move it up to the AW neck spec. My thoughts are if one anneals the brass the saami specs should be able to conform the neck back the the tighter configuration? Any of y'all annealing your ADG/ Peterson brass and after 4/5 reloads still able to get the neck to compress readily.

 

[Hard Head]

I have a 7mm PRC Bergara Wilderness HMR, using Peterson Brass, have loaded some cases 5 times use the Hornady head space gauge, after I measured a med. pressure load take that measurement and load ALL my rounds to that measurement, using Staball HD, 69.6 grains behind a 180 ELD Match, velocity has been at the constant 2915-2920 the last few sessions. There has never been a sticky case extraction, along with Fed 215 Mag. primers. Finally found that it likes the Hornady at .005 off the lands, shoots way better than I ever will and it wears a Trigger Tech set at .75 #s and it has a Area 4 port brake that is super. Pete

 

[Hard Head]

I have a 7mm PRC Bergara Wilderness HMR, using Peterson Brass, have loaded some cases 5 times use the Hornady head space gauge, after I measured a med. pressure load take that measurement and load ALL my rounds to that measurement, using Staball HD, 69.6 grains behind a 180 ELD Match, velocity has been at the constant 2915-2920 the last few sessions. There has never been a sticky case extraction, along with Fed 215 Mag. primers. Finally found that it likes the Hornady at .005 off the lands, shoots way better than I ever will and it wears a Trigger Tech set at .75 #s and it has a Area 4 port brake that is super. Pete

P.S. forgot to mention that upon closing the bolt there is a slight pressure closing it,Pete

 

[Shootin4fun]

The issue is the brass is too close in size to the SAAMI chamber at the base dimension. When you fire it, it can't really expand because it fits so tight. Then when you size the brass the die doesn't do anything because the brass didn't change dimension much at the base. If you make the die smaller, it can crack the die because you're trying to size down the thick solid case head that was too big to start. So since the brass doesn't get sized and doesn't expand it work hardens at the case head. With the AW reamers, the brass has room to expand outwards some and then the die can size it back down. The brass needs room to grow so then it can be sized down enough so it doesn't prematurely work harden. Others may be able to explain it better or have a better understanding of it, but that's my interpretation of the issues. Hornady should have spec'd the reamer .002 bigger at the 0.200 line on the reamer, or spec'd the brass .002 smaller at the base.

Edit to add, this isn't just a PRC problem. People have been fighting this for years with other reamers, dies, brass, etc. If you spec any reamer too small compared to the brass, you'll have this problem. If it's too big you can lose primer pockets prematurely. It's all a balancing act.

Thank you for the summarized explanation! I have been considering getting a PRC but haven't heard of this issue til now. . I have reloaded x000 rounds in my lifetime but never experienced this. I abandoned neck sizing 6 years ago, only did it for a year or 2. In a submanbun 6.5cm Xbolt using Lapua i am up to 14 reloads and still get SDs in the mid-low single digits. Interestingly, i have noticed some slightly stiff chambering on a batch but never any clickers in any caliber i have. Sounds like a small base die won't fix this because the web area cannot really be resized effectively anyway. I'm guessing that the expansion can only go so far, or else why would a larger chamber remedy the issue.

 

[Mcranch]

P.S. forgot to mention that upon closing the bolt there is a slight pressure closing it,Pete

I watched a video where the removed the plunger and pin from a bolt and used a case holder set that was in increments of .002 where it would bump the shoulder back to where the bolt would just fall with no pressure. Maybe you not bumping the shoulder back enough?

 

[Hard Head]

Might try after next time at the range I do know that even 1/16 turn of the die can make a big difference , Thanks, Pete

 

[charliehorse27]

Also for what it's worth, I was getting pressure signs with real mild loads and completely stumped initially. After I did the PRC clicker fix, all my early pressure signs went away along with the clickers.

 

[Mcranch]

Also for what it's worth, I was getting pressure signs with real mild loads and completely stumped initially. After I did the PRC clicker fix, all my early pressure signs went away along with the clickers.

What is the clicker fix? This is for the 7 prc.

 

[charliehorse27]

The issue is the brass is too close in size to the SAAMI chamber at the base dimension. When you fire it, it can't really expand because it fits so tight. Then when you size the brass the die doesn't do anything because the brass didn't change dimension much at the base. If you make the die smaller, it can crack the die because you're trying to size down the thick solid case head that was too big to start. So since the brass doesn't get sized and doesn't expand it work hardens at the case head. With the AW reamers, the brass has room to expand outwards some and then the die can size it back down. The brass needs room to grow so then it can be sized down enough so it doesn't prematurely work harden. Others may be able to explain it better or have a better understanding of it, but that's my interpretation of the issues. Hornady should have spec'd the reamer .002 bigger at the 0.200 line on the reamer, or spec'd the brass .002 smaller at the base.

Edit to add, this isn't just a PRC problem. People have been fighting this for years with other reamers, dies, brass, etc. If you spec any reamer too small compared to the brass, you'll have this problem. If it's too big you can lose primer pockets prematurely. It's all a balancing act.

The fix is using a specialized reamer that's a tiny bit larger at the .2" line to open up the chamber slightly. Alex Wheeler pioneered these reamers and the fix for them. The 7 PRC will have the problem same as the 6.5 and 300 PRC's.

 

[Tac-O]

Bigger freebores are good. Hornady likes to make fat bullets for some reason.

They're also good because they allow one to be lazy and not clean their rifle

 

[ottobounds]

So glad I found this thread. I have been dealing with clickers / sticky bolt on my 7PRC with loads that the rifle should have no issues with. Second firing on Peterson brass. I'll JGS Monday morning and hoping they have a reamer for me.

 

[ottobounds]

As an alternative to 4D, I have a 7 PRC AW reamer I rent out as a kit with the t-handle and cutting oil you'll need. I also have complete kits for rent for 6.5 PRC and 300 PRC too.

Hey CharlieHorse, I'm interested in renting your 7PRC kit. I'll message you.

 

[prcwv]

Same exact issue on 2nd fired Peterson. Charliehorses kit is what I used on mine.

So glad I found this thread. I have been dealing with clickers / sticky bolt on my 7PRC with loads that the rifle should have no issues with. Second firing on Peterson brass. I'll JGS Monday morning and hoping they have a reamer for me.