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Discussion Starter · #1 ·
I recently purchased a CAI C308, today I took it to the range for the first time, It cycled beautifully, and it did not jam once, but every few rounds I had FTFs due to light primer strikes. I checked to make sure the bolt was seated properly and everything looked OK. I also tried different mags and types of ammo, but the issue persisted. I am assuming it has something to do with the hammer spring not being strong enough, but I am not a G3 or CETME expert by any means.

On a side note when I purchased the rifle the charging handle was almost impossible to pull back, and when disassembling the bolt, I had to use pliers to remove the locking piece from the bolt carrier. Everything was so tight and needed to be polished to cycle smoothly. I finally have everything working smoothly, and I thoroughly cleaned the weapon before taking it to the range, but this light primer strike issue is a real pain.

Perhaps you guys have a solution for me?

Thanks in advance!
 

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Try a different firing pin, sometimes they use surplus parts and it may be worn; also remember that the Russian steel cased ammo has very hard primers compared to brass cased commercial or NATO ammo. Make sure the hammer is hitting the back of the firining pin squarely and solid. If the bolt head isn't fully in battery, you will definitely get let primer strikes for sure. There are a few things it can be. You should not need pliers to take out the Locking piece. Let us know
 

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tcr39 had great suggestions. I would replace the firing pin and spring with a new HK91 firing pin and spring from RTG. Also if you have not already done so tear the rifle down completely including removing the cocking handle and clean everything thoroughly. Sometimes with the Century builds there is a lot of gunk and residue left in the rifles when they leave the factory. You may have a problem with your cocking tube gap which could both make the rifle hard to cock and also give you a false bolt gap. You should check out Militaryfirearm that site used to be the Cetme owners site and they know everything there is to know about Cetmes. They will be able to get you up and running. You should read the following stickies: bolt gap, cocking tube gap and what to look for when buying a Cetme.
 

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Discussion Starter · #4 ·
Thanks for the advice guys.

I will order a new Firing Pin and Spring from RTG. I noticed the set comes with an HK91 locking piece, but I am not sure if it will work in the c308 /CETME BCG.

When I purchased the rifle I took it down completely for cleaning. The rifle was covered in grease and needed a serious cleaning and polishing just to function smoothly, In order to get the locking piece to come out without pliers I had to use a wire brush to get all of the gunk off of it. Everything is clean now, and works as it should.

I checked the cocking tube gap early on when troubleshooting the charging difficulty, but I wasn't having issues with the bolt unlocking, it was mostly resistance at the half way point, but after cleaning it's fine.

Besides the Firing Pin and Spring, do you think I should replace any parts or springs in the trigger group?
 

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Take the lower off and hand cock the hammer back to make sure the hammer shank and spring are working smoothly. Just push it back and dry fire it into the palm of your hand a few times. Just to check it. Oh ya, these rifles run better dry in my experience, maybe a little light CLP on the bolt group. But very dry.
 

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Discussion Starter · #6 ·
It seems to be working OK, but I noticed that the hammer smacks into the ejector lever, I am assuming that is normal? Also, this trigger pack looks nothing like the HK91/PTR91 Trigger packs. The Hammer Spring resembles an AR 15 Spring, i.e. no guide rod.
 

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Thanks for the advice guys.

I will order a new Firing Pin and Spring from RTG. I noticed the set comes with an HK91 locking piece, but I am not sure if it will work in the c308 /CETME BCG.

When I purchased the rifle I took it down completely for cleaning. The rifle was covered in grease and needed a serious cleaning and polishing just to function smoothly, In order to get the locking piece to come out without pliers I had to use a wire brush to get all of the gunk off of it. Everything is clean now, and works as it should.

I checked the cocking tube gap early on when troubleshooting the charging difficulty, but I wasn't having issues with the bolt unlocking, it was mostly resistance at the half way point, but after cleaning it's fine.

Besides the Firing Pin and Spring, do you think I should replace any parts or springs in the trigger group?
The HK91 locking piece is not compatible with the C308 which is a Cetme. The Cetme uses a different bolt carrier, locking piece and bolt. You may want to try HKparts or HKspecialist to see if you can get a new HK firing pin and spring cheaper there than the kit at RTG that includes the locking piece. If not you can probably sell the HK locking piece without a problem. Another good thing to get is a set or two of +2 and +4 rollers. As long as your gap is good now you will probably not need the rollers for a long time but if you are ordering anyway it might be a good idea to get some now. One other part that you may want to consider buying although you may not need it now is a spare bolt. Apex has new stripped Cetme bolts. I doubt if they have many of these and there will probably never be anymore new Cetme bolts so it would be a good idea to have one. These rifles do have a break in period where the parts settle together. This can take a few hundred rounds and your bolt gap my drop a couple of thousands. Once the rifle is broke in if it is still having problems then you may need to replace other parts.
 

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It seems to be working OK, but I noticed that the hammer smacks into the ejector lever, I am assuming that is normal? Also, this trigger pack looks nothing like the HK91/PTR91 Trigger packs. The Hammer Spring resembles an AR 15 Spring, i.e. no guide rod.
The C308 has a Cetme fire control group in a US made PTR navy style lower. On militaryfirearm there is a thread about the Cetme FCG with instructions on assembly and disassembly. You can swap in an entire HK fire control group if you want to change it out (you would also need to change the selector to a HK one for the plastic lower).
 

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Discussion Starter · #9 ·
Thanks, I will be sure to pick up some CETME bolts. Regarding the hammer hitting the front of the ejector lever, is that normal?

I personally feel it could be one of two things, the hammer is just not hitting the firing pin hard enough, or the firing pin is slightly worn out to the point of not properly impacting the primer.
 

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No ,because the hammer hits the back of the carrier way before it goes that far forward when the lower is off like that. Make sure that locking piece isn't dragging or holding up the bolt head from going into full battery. Clean the roller recess inside the trunion real good just to make sure. Like Great 308 said, sometimes these century rifles need debugging. But so do PTR91 rifles at times. You,LL get it. Welcome aboard bro.
 

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Discussion Starter · #12 ·
Understood, I put the lower back on and see that the hammer doesn't hit the ejector lever when assembled. I will check the trunion again to make sure it's cleaned. I have ordered a new firing pin and spring from HKParts and will keep you posted if that fixes the issue. If that doesn't do it, I will replace the bolt latch and spring, to rule out possible bolt bounce. Lastly, if that doesn't fix the issue I will drop in a new trigger pack and selector, ruling out a weak hammer spring issue. Hopefully it's just a worn out firing pin. Thanks for all of the advice, I will keep you guys posted.
 

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Discussion Starter · #13 ·
Try a different firing pin, sometimes they use surplus parts and it may be worn; also remember that the Russian steel cased ammo has very hard primers compared to brass cased commercial or NATO ammo. Make sure the hammer is hitting the back of the firining pin squarely and solid. If the bolt head isn't fully in battery, you will definitely get let primer strikes for sure. There are a few things it can be. You should not need pliers to take out the Locking piece. Let us know
Sorry for the delay on the update, but I wanted to be certain the problem was 100% fixed before reporting back. Back in March I ordered a brand new HK G3 Firing Pin & Spring Combo, fixed the problem completely. I was surprised that's all that was needed but she runs great now, 400 rounds since the new firing pin and no hiccups. Thanks for advice!
 

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Thanks for the update and glad it's working for you now.

Perhaps the original CETME firing pin had seen a lot of use and was simply worn down enough to not quite reach sometimes. Did you compare the lengths and/or tips of both pins?
 

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Discussion Starter · #15 ·
Thanks for the update and glad it's working for you now.

Perhaps the original CETME firing pin had seen a lot of use and was simply worn down enough to not quite reach sometimes. Did you compare the lengths and/or tips of both pins?
I did compare, there was a slight difference in length, but I noticed the new firing pin spring was much better, I think the old spring was worn enough where the sides of the firing pin were scraping against the firing pin channel causing too much friction, that mixed with a worn down firing pin caused the issue.

I am curious if the old pin would work with the new spring to test my hypothesis, I will check next time I go to the range.
 

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I did compare, there was a slight difference in length, but I noticed the new firing pin spring was much better, I think the old spring was worn enough where the sides of the firing pin were scraping against the firing pin channel causing too much friction, that mixed with a worn down firing pin caused the issue.

I am curious if the old pin would work with the new spring to test my hypothesis, I will check next time I go to the range.
I am sure your original spring is slightly worn. However, if you compared a NOS Cetme spring and a new HK91 spring the HK spring is stiffer.
 

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I did compare, there was a slight difference in length, but I noticed the new firing pin spring was much better, I think the old spring was worn enough where the sides of the firing pin were scraping against the firing pin channel causing too much friction, that mixed with a worn down firing pin caused the issue.

I am curious if the old pin would work with the new spring to test my hypothesis, I will check next time I go to the range.
The firing pin spring is there to retract the firing pin and so a stiffer spring would exacerbate the issue if that were the case. It is the hammer spring that influences the strike of the firing pin on the primer. Weak hammer spring = weak primer hits and vice-versa.

It only takes a tiny difference in length on a firing pin to cause issues.
 

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Help also needed. I have a problem similar to this.

1) Rollers seem to lock into place fine.

2) Every fifth cycle or so, the Bolt Carrier doesn't come all the way forward. Often it'll fire anyway, but probably once or twice a magazine it will light primer strike. When I pull the trigger, the hammer will drive the carrier the rest of the way forward.

3) Gap is .4mm or .016". Cocking tube gap matches the bolt gap. For kicks and giggles I tried +4 rollers, but it had no noticeable effect one way or the other in stopping this.

4) I tried an HK recoil spring, but when I did this it not only made the problem occur 100% of the time, the cocking handle would not fold flat against the tube at the end of a cycle and the bolt was not going into battery at all. Do I just need the heavy recoil spring AND a new cocking handle spring?

5) I've disassembled and cleaned this whole rifle many, many times.

6) Could the locking lever be causing this? As in, is the bolt and bolt carrier bouncing back out of battery every time the bolt slams forward?

7) Yes I'm slapping the cocking handle.

8) I have removed the hand grip housing that holds the trigger group to make sure nothing in the trigger group was interfering with the action. No change. Every few cycles the bolt carrier will not quite move all the way forward.

9) Nothing appears to be slowing it down as it travels forward. No burrs or dents or bulges that I can find. Rollers aren't denting the receiver anywhere that I can see.

10) The only thing I haven't done is the 300 rd break-in, but I do not have the time or the money to burn through 300 rds of .308 right now.

The only things I can think of to replace or do are the following:
1) cocking handle spring (as stated above, if I put a new recoil spring in, the cocking handle will not lock closed, it sticks out at 90 degrees)
2) Firing pin and spring
3) Locking lever spring (and maybe the locking lever itself? Is it worn? How can you tell??)
4) Bolt carrier do I just need to polish the inner-channel where the locking piece rides?

Please advise if you can, thanks.
 

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I am no expert at this.
I have doubts 1 is the problem with light strikes. IF the carrier is not going all the way forward there may be a problem with the components with respect to the cocking tube regarding dirt, friction and fit but if the cocking handle spring is installed right the power of the spring itself or lack thereof should not cause the bolt not to go all the way forward. If the spring is incorrectly installed it may contribute to more friction and binding.

2) Again this can well be a cause of light strikes but it should not cause the bolt not to close. As noted above take them out of the assemble and make sure they are clean and burr free and that the mechanism is working/moving smoothly.

3) Check this for burrs and rough spots particularly on the lever and the mating portion of the bolt head.

4) make certain it is clean and not rough. This goes for all mating/sliding/working surfaces.

5) as mentioned in one of the above replies, make certain the roller recesses in the trunion are cleaned out and don't have any buildup in them.
 

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Update.

1) Okay, I checked the locking lever. It was rough and gritty, so I lightly sanded it with some 2000 grit sandpaper. No effect.
2) Checked the locking lever spring. It seemed pretty strong still, so I decided to leave it alone but revisit if I can't fix the problem elsewhere.
3) Changed the firing pin spring. No effect. As Starwolf advised, it probably wouldn't work. However, I will say that the new spring is a LOT stiffer than the old one. I don't regret spending the money to get a new HK firing pin spring, especially when some people have complained of dimpled primers or even slam fires. Having a little extra pressure holding that firing pin back when the bolt slams forward seems prudent.
4) Lightly sanded the last inch or so of the bolt carrier tube that mates with the cocking handle tube support piece that the cocking handle attaches to. It seemed a little rough, as did the interior walls of the support tube, so sanded it as well. Didn't seem THAT rough to cause this issue but did it anyway just in case.
5) Replaced the cocking handle spring. Now the rifle cycles reliably. I cycled the rifle about 20 times or so without a single issue. Before the replacement, it would fail to go completely into battery every 5 cycles or so. Examining the old spring, it seemed a little bent, deformed, and weak, so this may have been the problem. It may have been slowing it down just enough to cause my failure.

It seems to be functioning now, so I'll continue to check how it's cycling and report any further issues. So, I just want to thank @StarWolf for the help.
 
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