if he was only having tight brass I'd agree with you, but seems hes also getting ejector marks, Personally I'd wager he's making pressure for what ever reason, I'd back the load off
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Sticky Bolt Ideas?
- Thread starter ottobounds
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Taylor, good advise to consider. I would make sure that the chamber is bone dry. I am dealing with this issue right now on a different caliber, brass is too large for the chamber.
I had the same thing happeing on my brass. My assumption, which is why I honed the chamber after speaking to Dave Manson, is that the brass didn't have enough space to expand in diameter in the tight chamber and so it grew more so in length and was not able to spring back as it would in a more optimally sized chamber. Once I expanded my chamber diameter, per Dave Manson's recommendation, the brass expanded and sprang back as it should. The brass goes plastic during the ignition/expansion process. I can now use higher pressure loads in that chamber without the issues observed previsouly - all within reason of course. That short barreld 30-06 shoots .5 MOA with brass FL and neck sized with any and all of my 3 sets of dies. I have lightly honed all of my chambers to ensure they are less likely to cause problems, and I always run Brake Cleaner on an oversized cotton swab (bought a bunch at the autoparts store) through the chamber to clean the gunk out - they get crusty.
That's the sum of my tight chamber experiences - sort of.
AckleyFan, how much did you open up the chamber?
My measurements noted it at one and a half thousandths (.0015) but might come out a bit more based on fired cases. My calipers aren't very high quality.
So, if you took a new case, subtracted the new web dia, what would the new clearance be?
Thank you to all who replied. I'm going to talk to a 'smith about the chamber honing option just to get a feel for that process. I'm trying to balance the potential for unintended consequences versus my expectation of what this gun "should" handle and what it "will" handle. If I'm sold on the honing solution then I'll try it. If not then…
Obviously the next step is to move down to the 2800fps through 2900fps range for the next batch of loads. I'll also try some Hornady once fired brass just to compare that to the Peterson brass. If the gun runs happy without pressure signs and shoots good groups at the lower velocities then oh well. Not confident about that but we'll have to wait and see. Pretty sure it'll still kill game at 2800fps but anything lower than that I I'll have to start looking and other bigger issues. It's just not what I was hoping to see out of this rifle.
Thanks again y'all.
Obviously the next step is to move down to the 2800fps through 2900fps range for the next batch of loads. I'll also try some Hornady once fired brass just to compare that to the Peterson brass. If the gun runs happy without pressure signs and shoots good groups at the lower velocities then oh well. Not confident about that but we'll have to wait and see. Pretty sure it'll still kill game at 2800fps but anything lower than that I I'll have to start looking and other bigger issues. It's just not what I was hoping to see out of this rifle.
Thanks again y'all.
I do know there was a mismatch at the 200 line of the 6.5 and 300 PRC cases. I know @Alex Wheeler had reamers to correct these issues, maybe there's one for the 7 PRC also?
I didn't document all this before I gifted the rifle to my hunting buddy for his retirement. Dave was giving me min/max specs on chamber/cartridge measurements. If I recall correctly he was suggesting .003 - .004 clearance. I was working with him on a few items. Factory 280AI brass is about minimum SAAMI spec where chambers and reamers tend to be at maximum spec - so I'm getting bulging cases after firing @ the start of the web. I have to live with this until I decide to rebarrel and use my custom ground reamer, then start all over. I want .466" at the .200 line for my 280AI's and 257AI, not .471" due to the small brass diameters. Living and learning...
I'll look for my notes on the 30-06 jic.
Try small base sizer.
.003-.004 is a minimum, not a maximum. After brass has been shot some, it will begin normalizing, springing back out. You do not want to find yourself with a box of ammo that has sprung back out and is difficult to chamber. I have had it happen on two occasions. Any ammo that has been loaded for 5 years or so, I cycle though the gun prior to a hunt, and I keep a Redding body sizer on hand for that caliber just in case, so I can size the loaded ammo. This issue happens when I have bought once fired brass that was test fired in bolt action rifles.
After doing more research, yes, there is an Alex Wheeler (AW) reamer for the 7PRC. JGS sells them. charliehorse27 on this forum has a reamer kit that he'll rent. I'm just waiting for the kit to be available then I'll get on with fixing my rifle.
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Some gunsmiths familiar with the technique can hone out a chamber to the desired dimensional size. This is not as uniform as if a reamer was used, but it has done the job for me on a couple of occasions where brass was too large for the chamber. The issue I had was using Lapua brass in std SAAMI spec American chambers, which is CIP European Spec vs SAAMI Spec. When the brass is too large, often there is a Full length die issue....URRGGG.....
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Good Morning y'all. Finally got a bit of a cool off in the desert so I could test the fix. Problem solved! Thanks to charliehorse27 for the reamer rental. Heavy bolt lift is GONE. No more early pressure signs. Finished shooting the remainder of my second firing load development and all good. I also decided that my initial batch of Peterson brass had likely been unfairly abused during this experience so I started a new batch of brass down the path to getting my hunting load dialed in. Lots of components used but I suppose that's the cost of my education.
Thank you for all of your input!
Thank you for all of your input!
