7mm PRC

[WapitiBob]

It's a Ridgeline thing. It smoothes out over 100-150 rounds

yep, and a long thread on those rifles and ejector marks

 

[Cruzer]

I finally was able to buy six boxes of 7mm PRC (Precision Hunter) for my new Christensen Arms Ridgeline. While going through the break-in sequence, I measured an average of 2903 fps (4,500 ft. elevation, 30 F).

I noticed the bolt being a bit difficult to lift after a shot but didn't think much of it until after 3 boxes... Every single rounds have over-pressure signs - flatten primer and extractor marks! I was absolutely surprised that factory ammo would be that high on pressure. I've been brushing and cleaning the bore every 3 rounds for the break-in.

Is that something anyone else noticed? I was planning to reload with H4831SC at 60 to 62.5 grains, to try to get close to the same velocity, but I'll wait to figure things out.

My buddy had some issues with this as well. 7MM PRC ridgeline. Blowing out primers and having hard extractions of the casings. It could've been from the break in process. By that I mean, we were not getting all the Copper 9 solvent out of the chamber and bore, there for, IMO causing some left over accelerant product of combustion in there causing a higher explosion temp. and psi. Therefore causing greater case expansion and not allowing for spring back and also causing primers to blow. Soooo we did a totally thorough cleaning and its seems the issue was no longer. So during barrel break in, be sure to inspect the receiver ring and the chamber for contaminants.

 

[vancewalker007]

My buddy had some issues with this as well. 7MM PRC ridgeline. Blowing out primers and having hard extractions of the casings. It could've been from the break in process. By that I mean, we were not getting all the Copper 9 solvent out of the chamber and bore, there for, IMO causing some left over accelerant product of combustion in there causing a higher explosion temp. and psi. Therefore causing greater case expansion and not allowing for spring back and also causing primers to blow. Soooo we did a totally thorough cleaning and its seems the issue was no longer. So during barrel break in, be sure to inspect the receiver ring and the chamber for contaminants.

Don't know if you have one but a little additional cleaning kit like the Tipton product is handy for that final fluid cleanup afterwards. I always swab out my chambers and around locking lugs JIC.

Tipton Action Chamber Cleaning Tool Kit

Cleans the grit from the bolt lug recesses and the bolt raceways in the action. Set includes; Action Cleaning Tool and 10 swabs, Chamber Cleaning Tool...

www.midwayusa.com

 

[cynjon]

I finally was able to buy six boxes of 7mm PRC (Precision Hunter) for my new Christensen Arms Ridgeline. While going through the break-in sequence, I measured an average of 2903 fps (4,500 ft. elevation, 30 F).

I noticed the bolt being a bit difficult to lift after a shot but didn't think much of it until after 3 boxes... Every single rounds have over-pressure signs - flatten primer and extractor marks! I was absolutely surprised that factory ammo would be that high on pressure. I've been brushing and cleaning the bore every 3 rounds for the break-in.

Is that something anyone else noticed? I was planning to reload with H4831SC at 60 to 62.5 grains, to try to get close to the same velocity, but I'll wait to figure things out.

I had something similar happen...I have a new 22" Carbon6 prefit that I added to a Bergara B-14 action. The plan was to use factory ammo for barrel break-in, so I bought 7 boxes of factory Hornady ammo (60 of the 180 ELD-M and 80 of the 175 ELD-X). At around the 35 round point, halfway through a box of the 175's, I started getting a heavy bolt lift with every round. I had been cleaning every 5-10 round through the initial break-in, and getting zero copper out of the barrel which I was very happy with. After the bolt lift started getting heavy, I took it home and cleaned it again...no copper and a very clean barrel. I remembered reading that the early Hornady factory ammo was supposedly loaded with RL-26, and has given me issues with carbon rings in other rifles unless carefully managed (.22 Creedmoor, fast twist .243). I ran the borescope down the barrel, and sure enough, there was a ton of carbon in the neck area of the chamber. I gave that a good cleaning, and when I resumed firing the box of ammo that had given me 6 consecutive heavy bolt lifts and ejector marks, the remainder of the box fired perfectly with no pressure signs. I do believe that soft Hornady brass is a big part of the problem, and intend to switch to the ADG brass that I already have on hand once the barrel is broken in.

I'm not saying that's the issue you were seeing, but it might be worth checking out.