Ok here goes. I have a CMMG with the gas piston and for what ever reason I have had to replace 4 hammer pins due to them shearing. I have contacted CMMG and their suggestion is to try KNS pins. Either that or send it back to them. The round count is around 1000+. Any ideas?
- Thread starter jwilly
- Start date
Re: CMMG hammer pin
I'm guessing that you're also experiencing more of a recoil impulse than DI 223/556 guns too? Might want to try a heavier buffer, it sounds like its running with a faster cycle or more violent BCG travel. This isn't unheard of on piston AR's. Is your disconnector peened where the hammer tail comes may hit it too?
I'm guessing that you're also experiencing more of a recoil impulse than DI 223/556 guns too? Might want to try a heavier buffer, it sounds like its running with a faster cycle or more violent BCG travel. This isn't unheard of on piston AR's. Is your disconnector peened where the hammer tail comes may hit it too?
Re: CMMG hammer pin
Try asking them why their piston kit is operating so violently as to be shearing hammer pins like there's no tomorrow and ask them if that is considered "normal" operation for their kit to chew through hammer pins like that? I'm pretty sure their answer should be "nope...that's not normal."
Before that, what buffer/spring setup are you running? Also, what ammo are you using?
Depending on the answer to those questions, you can first try a heavier buffer and/or an XP buffer spring to see if that minimizes the force of the carrier on the hammer which is in turn causing your hammer pins to break. The KNS pins are also a good insurance policy against both broken pins as well as damage to your lower receiver from the impact wobbling your hammer pin out of spec.
Try asking them why their piston kit is operating so violently as to be shearing hammer pins like there's no tomorrow and ask them if that is considered "normal" operation for their kit to chew through hammer pins like that? I'm pretty sure their answer should be "nope...that's not normal."
Before that, what buffer/spring setup are you running? Also, what ammo are you using?
Depending on the answer to those questions, you can first try a heavier buffer and/or an XP buffer spring to see if that minimizes the force of the carrier on the hammer which is in turn causing your hammer pins to break. The KNS pins are also a good insurance policy against both broken pins as well as damage to your lower receiver from the impact wobbling your hammer pin out of spec.
Re: CMMG hammer pin
See, this is why I love the hide. No B.S. answers. Thanks for the replies! As for the buffer spring, I couldn't tell you. It is their spring. Happens with both 5.56 factory and .223 hand loads. Nothing compressed, 26 gr. of BL-C2. This is my first AR so just cutting my teeth with this one. The only thing that I have don't to it is a 512. I will be ordering up the KNS pin kit any preference from their gen 1 or 2? Also what can you tell me about changing the buffer spring? How heavy should I go?
See, this is why I love the hide. No B.S. answers. Thanks for the replies! As for the buffer spring, I couldn't tell you. It is their spring. Happens with both 5.56 factory and .223 hand loads. Nothing compressed, 26 gr. of BL-C2. This is my first AR so just cutting my teeth with this one. The only thing that I have don't to it is a 512. I will be ordering up the KNS pin kit any preference from their gen 1 or 2? Also what can you tell me about changing the buffer spring? How heavy should I go?
Re: CMMG hammer pin
http://stores.homestead.com/Laruetactical/Detail.bok?no=126
and try this too, perhaps.
http://www.spikestactical.com/new/z/lower-parts-spikes-stt2-heavy-buffer-p-201.html
By no means is this "the" answer for all issues. Just a good start. As far as the KNS pins, I don't know which is better, it may be personal preference or aesthetics.
http://stores.homestead.com/Laruetactical/Detail.bok?no=126
and try this too, perhaps.
http://www.spikestactical.com/new/z/lower-parts-spikes-stt2-heavy-buffer-p-201.html
By no means is this "the" answer for all issues. Just a good start. As far as the KNS pins, I don't know which is better, it may be personal preference or aesthetics.
Re: CMMG hammer pin
I wouldnt change anything it would be going back to the manufacturer. After that spikes buffer as was suggested and depending on the current trigger a spikes enhanced lpk only because it has most of the upgrade goodies like kns pins.
I wouldnt change anything it would be going back to the manufacturer. After that spikes buffer as was suggested and depending on the current trigger a spikes enhanced lpk only because it has most of the upgrade goodies like kns pins.
Re: CMMG hammer pin
If you are shearing hammer pins this frequently, a stronger pin is not the answer. If there is sufficient energy to break pins, watch the bores of of the pin holes - they are getting an excessive pounding and getting wallowed out!
Resolve the problem with buffer and/or spring, not a stronger pin.
Kevin
If you are shearing hammer pins this frequently, a stronger pin is not the answer. If there is sufficient energy to break pins, watch the bores of of the pin holes - they are getting an excessive pounding and getting wallowed out!
Resolve the problem with buffer and/or spring, not a stronger pin.
Kevin
