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Thread: New member with a c308 guestion

  1. #11
    New Recruit Has Been's Avatar
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    No rollers today. Once again the USPS has failed to deliver.

  2. #12
    New Recruit Has Been's Avatar
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    USPS finally got around to delivering the rollers and new recoil spring today. I put in the -6 set and that brought bolt gap down to .014". Carrier OAL is 10 7/8" and C tube gap is now .020" + or - .001".
    New German made recoil spring measured 18 5/8" OAL vs 17 9/16" OAL for the original one. Also noticed wire gauge was a tad smaller in diameter on the new one, .045" new .050" old. Just going by feel the new one doesn't seem to be as strong as the old one either. Might rig up a scale to see. Now I'll run a few mags and check BG again. Before I do does everything seem to be reasonably within spec now or did i miss something?
    Last edited by Has Been; 06-06-2019 at 05:18 PM. Reason: Correcting bloody typos....

  3. #13
    holescreek's Avatar
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    If my memory is working I think the original Cetme spring is a constant 12 pound force. I measured several a very long time ago for a custom build. Maybe the Germans added the inch to make up for the wire size.

  4. #14
    New Recruit Has Been's Avatar
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    Update: after 80 rounds BG is still pretty much where it started out at .014".
    Bad news is my suspicions about the new recoil spring
    not being up to snuff were confirmed. After only 80 rounds it now measures 17 1/8" OAL relaxed, thats 1 1/4" shorter than it was new. It was still working the action reliably but recoil was starting to beat me and the rifle pretty hard.
    Also, the roller dents appear to be more noticeable than before and there are now 2 cracks in the G3 wood buttstock. Dont know if the spring had anything to do with the cracks but I dont know what else would've caused them.
    The spring came from HK Parts, its advertized as a new factory H&K recoil spring for the G3, HK 91 and PTR 91 and clones, sku number is 00360 IIRC. Maybe just a bad one but I won't be buying anymore of them.
    Last edited by Has Been; 06-10-2019 at 08:53 PM.

  5. #15
    Senior Veteran SgtHorvak's Avatar
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    Hopefully Holes, or someone who knows much more about these rifles than ME, and my limited experience, will chime in, but I'm wondering about your bolt gap measurement. Seems more like THAT could be the issue here. It's pretty normal for recoil springs to "shrink" a bit once they've been doing their job. It sounds to me as if your bolt gap is not what you think it is...Others, what say you??!!

  6. #16
    New Recruit Has Been's Avatar
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    I'm confident BG measurement is true. It appears this particular c308 with built with new or excellent condition parts. I can find no wear in the roller windows, on the locking piece shoulders, carrier or trunion. I checked them by running a pick across the bearing surfaces, not even a hint of a roller divot.
    As far as the spring goes, if it was made to spec out of good quality material there should be very little to no change in relaxed length in this short amount of use. This thing collapsed in under 80 rounds. I sorry to be disagreeable but to loose 1 1/2" in length in what amounted to only minutes of use is, in my experience, a sure sign of a poor quality spring.
    I'm hoping the crappy spring is the culprit that caused the stock cracks and slight deepening of the roller dents but in the back of my mind I have an idea it may be more serious, like the barrel not being pressed in quite far enough letting action lock up further up on the trunion shoulders than normal

  7. #17
    Senior Veteran SgtHorvak's Avatar
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    Quote Originally Posted by Has Been View Post
    I'm confident BG measurement is true. It appears this particular c308 with built with new or excellent condition parts. I can find no wear in the roller windows, on the locking piece shoulders, carrier or trunion. I checked them by running a pick across the bearing surfaces, not even a hint of a roller divot.
    As far as the spring goes, if it was made to spec out of good quality material there should be very little to no change in relaxed length in this short amount of use. This thing collapsed in under 80 rounds. I sorry to be disagreeable but to loose 1 1/2" in length in what amounted to only minutes of use is, in my experience, a sure sign of a poor quality spring.
    I'm hoping the crappy spring is the culprit that caused the stock cracks and slight deepening of the roller dents but in the back of my mind I have an idea it may be more serious, like the barrel not being pressed in quite far enough letting action lock up further up on the trunion shoulders than normal
    Maybe you're right ...but I've never known HkParts to sell crappy parts, though any part CAN, admittedly, slip past QC. However, I've seen quality 1911 recoil springs, Orion 7 M1 Garand springs, among others, ALL lose some length upon firing a few rounds. I actually EXPECT it. But hell, who knows?? It just sounds like a bad ramp on the bolt head, and/or locking lever, or the rollers not being held properly in the trunnion(which would indicate worn parts or bolt gap issues). Hopefully, someone who knows more than I do will get ya figured out. I'd be looking at your locking lever/bolt head ramp, in the mean time.

  8. #18
    holescreek's Avatar
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    Quote Originally Posted by Has Been View Post
    I'm confident BG measurement is true. It appears this particular c308 with built with new or excellent condition parts. I can find no wear in the roller windows, on the locking piece shoulders, carrier or trunion. I checked them by running a pick across the bearing surfaces, not even a hint of a roller divot.
    As far as the spring goes, if it was made to spec out of good quality material there should be very little to no change in relaxed length in this short amount of use. This thing collapsed in under 80 rounds. I sorry to be disagreeable but to loose 1 1/2" in length in what amounted to only minutes of use is, in my experience, a sure sign of a poor quality spring.
    I'm hoping the crappy spring is the culprit that caused the stock cracks and slight deepening of the roller dents but in the back of my mind I have an idea it may be more serious, like the barrel not being pressed in quite far enough letting action lock up further up on the trunion shoulders than normal
    Take a look at the bolt locking pawl and the ramp on the bolt head that it rides on. Also, the spring under the bolt locking pawl. I have photos of bad ones in my C308 good,bad,ugly thread.

    The recoil spring may have something to do with it or it could just be a victim of a weak locking pawl spring. The Locking pawl is the only thing holding the bolt closed long enough for the majority of the gas to leave the end of the barrel before opening to eject the empty brass. If the pawl is worn, spring is weak, or the bolt head ramp isn't crisp the bolt will open too soon and hammer the buffer deploying the rollers. Even a perfect factory recoil spring cannot stop this.

    How easy is it to push/pull the bolt head in the carrier by hand? If you can pull it at all without squeezing the rollers in a vise your spring is probably toast. If it is the spring, buy one from RTG, Apex springs are too weak.

  9. #19
    New Recruit Has Been's Avatar
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    Quote Originally Posted by holescreek View Post
    Take a look at the bolt locking pawl and the ramp on the bolt head that it rides on. Also, the spring under the bolt locking pawl. I have photos of bad ones in my C308 good,bad,ugly thread.

    The recoil spring may have something to do with it or it could just be a victim of a weak locking pawl spring. The Locking pawl is the only thing holding the bolt closed long enough for the majority of the gas to leave the end of the barrel before opening to eject the empty brass. If the pawl is worn, spring is weak, or the bolt head ramp isn't crisp the bolt will open too soon and hammer the buffer deploying the rollers. Even a perfect factory recoil spring cannot stop this.

    How easy is it to push/pull the bolt head in the carrier by hand? If you can pull it at all without squeezing the rollers in a vise your spring is probably toast. If it is the spring, buy one from RTG, Apex springs are too weak.
    Ok, I had a look at the pawl and the bolt ledge the pawl locks onto. The parked finish is worn through as is to be expected but I can not see or feel any appreciable wear in the parts themselves.
    The spring I did not remove, but it is not broken and seems to be putting plenty force on the pawl. With the bolthead removed and a small piece of wood on the pawl's now exposed "hook" I could compress the spring with thumb pressure but it took some doing. IMO the spring is good but plan to order another one and a pawl in the near future.
    Next I reassembled the BCG to see how much force it took to push the bolt head in to the locked position. I could hold the carrier in one hand and push the bolt head in with my thumb. I'd say it took a moderate amount of force.
    As far as pulling it back out by hand, forget it, there ain't no way. I could pry it apart with a screwdriver but it took quite a bit of pressure to unseat the pawl. To me it has a good grip on the bolt head.
    With the carrier assembly out of the reciever bolt gap goes to zero, as it should, when the bolt head is pushed in. With my assembly there is .013" free travel before the pawl engages the bolts locking ledge. I assume this is normal?
    I believe the bad recoil spring was the source of my latest troubles but as I mentioned earlier plan to ordering a new pawl and spring shortly just for comparison.
    One other thing I did was grind a punch to match the rail contour so I could remove the roller dents.

  10. #20
    holescreek's Avatar
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    Does your locking piece have a "50" on it?

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