Protrusions caused by ejector pins

Elk_Hunter

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Hey,
I recently bought a Fierce arms rifle in 300 PRC. When I took it to the range for the first time, I immediately noticed that the bolt lift gets heavier after furring and that there are 2 protrusions on the case where the ejector pins sit (see picture). My first thought was that the ammo might be too hot but seemed somewhat unlikely since it is Hornady factory ammo out of two different lots. I did not have the opportunity to measure with a chronograph. In a different thread here I red that it might be due to tolerances, soft brass or oil in the chamber. It just seems strange to me that it would cause protrusions rather than indentations. I have 2 more ammo boxes on the way from 2 different manufacturers to see if it's the same or not. If it matters, the diameters almost match perfectly and the protrusion is about 0.0030 although it's kind of hard to measure. Anyone have any other ideas?
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Hey,
I recently bought a Fierce arms rifle in 300 PRC. When I took it to the range for the first time, I immediately noticed that the bolt lift gets heavier after furring and that there are 2 protrusions on the case where the ejector pins sit (see picture). My first thought was that the ammo might be too hot but seemed somewhat unlikely since it is Hornady factory ammo out of two different lots. I did not have the opportunity to measure with a chronograph. In a different thread here I red that it might be due to tolerances, soft brass or oil in the chamber. It just seems strange to me that it would cause protrusions rather than indentations. I have 2 more ammo boxes on the way from 2 different manufacturers to see if it's the same or not. If it matters, the diameters almost match perfectly and the protrusion is about 0.0030 although it's kind of hard to measure. Anyone have any other ideas?
View attachment 600808View attachment 600809
The brass actually pushes back the ejectors and is forced into the recess of the bolt face, (over pressure)
 
I would agree with the above statements. Not familiar with Fierce but the few Christianson rifles I've dealt with have hit pressure way early. One 6.5 PRC was too hot with factory ammo.
 
Out of spec chamber or bore dimensions
Good point and even without having tested any other ammo, I might have found the issue. The headspace (at least I think that is what it's called) seems to be way off. It's hard/impossible to tell on the picture, but the case bottom sticks out quite a bit so I'm guessing they messed up setting the headspace correctly. How this ever passed the Go/Nogo gauge is a mystery. Not sure if I even should try different ammo with that being the way it is?
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I'm willing to bet the pressure is just fine. I would look at the manufacturer and how soft the brass is.
An that note though, even with a live unfired factory round, just by closing and opening the bolt a couple of times, I can see that brass gets smeared for lack of better term on the bolt face. Just doesn't seem right that the cartridge sticks out like 2 mm or so when all my other rifles are seated flush. New ammo should arrive next week so I'll report back after more testing.
 
You will need to measure your headspace to confirm, this is from the sholder of case to the bolt face, check the non fired brass with the fired brass for dimensions. Pull a projectile and test the bolt closing, could be throat dimensions as well, projectile jamming into the lands.
 
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