[chad_ctdesign]

Cohaire 9mm SD ran great with my postie sef pack..sold my posties and bought a flemming sear in a sef pack and every 3rd round it jams..crushed casing and a lose round that falls out when I pull the mag. It was from a mp5k..no timmed hammer. Thought this one was going to be easy.

 

[axehole]

I would try different ammo (hotter) or look at locking piece.

 

[retrodog]

How does the new pack do in other firearms?

Using hotter ammo is not necessarily the way to handle it, but could help to determine the nature of the problem. This is a gun with a ported barrel to release pressure and keep the bullet from breaking the sound barrier. Using super hot ammo was not intended as it could have weird effects on other things, i.e. going supersonic and putting a lot of extra pressure through the ports.

Check the bolt head to make sure your extractor spring didn't weaken. Check the ejector lever in the new pack to make sure it is the newest generation with the little hump on the rear back side. Check current bolt gap.

Finally, use some good quality ammo like S&B 115 grain or WWB. These should both run fine in an SD type gun.

 

[Wolvenhaven]

Make sure the pack is sitting in the housing correctly, it could be canted too far forward or back.

 

[Chopstix Kid]

Get a re-timed hammer and make certain you have 9mm hammer spring. Also make sure the sear spring isn't binding or hitting the main trigger sear. Wont cause your issue but is a common problem.

As noted earlier, make sure the lower has no movement on the gun.

 

[chad_ctdesign]

Using the same ammo, military wolf.

 

[retrodog]

Using the same ammo, military wolf.

That should be fine.

 

[axehole]

My SD loves Wolf but it had to have the locking piece worked on or changed.

I am not sure all SD's necessarily drop velocity below supersonic. The HK ones do and many manufacturers strive for that but not sure everybody that makes a SD clone is accomplishing that.

 

[kwesi]

My rounds chrono'd appx. 225 FPS less in the Coharie SD using Fiocchi 115gr. They ended up around 975-1000 FPS.

 

[retrodog]

My rounds chrono'd appx. 225 FPS less in the Coharie SD using Fiocchi 115gr. They ended up around 975-1000 FPS.

Less than what? A gun with a 4-5" barrel? That would be a fair comparison. I'm guessing you used your K as a comparison. I'm going to have to consider doing that as well, just out of curiosity.

My SD loves Wolf but it had to have the locking piece worked on or changed.

I am not sure all SD's necessarily drop velocity below supersonic. The HK ones do and many manufacturers strive for that but not sure everybody that makes a SD clone is accomplishing that.

It would be difficult for me to believe that they didn't. It's just dictated by the number of holes that they drill in front of the chamber. And the diameter of course. This isn't some radical new technology that was recently developed by NASA and uses special materials like unobtainium. It's just drilling a few holes in a barrel to let the pressure escape. It's about as simple and cheap as you could ask for.

 

[Chopstix Kid]

As the OP noted, gun ran fine with a postie pack. I'm leaning towards a pack issue, not ammo. He also noted lack of a retimmed hammer. I'm guessing incorrect pack setup and/or fitment issue with the SEF housing. Just my 2-cents.

 

[axehole]

Less than what? A gun with a 4-5" barrel? That would be a fair comparison. I'm guessing you used your K as a comparison. I'm going to have to consider doing that as well, just out of curiosity.
It would be difficult for me to believe that they didn't. It's just dictated by the number of holes that they drill in front of the chamber. And the diameter of course. This isn't some radical new technology that was recently developed by NASA and uses special materials like unobtainium. It's just drilling a few holes in a barrel to let the pressure escape. It's about as simple and cheap as you could ask for.

Kind of rude sarcastic response don't you think?

 

[retrodog]

Kind of rude sarcastic response don't you think?

No, not really. Well I don't think it was rude and sarcastic towards you. That certainly wasn't my intent anyway. If anything, I was merely trying to point out the fact that the design is not very complex, nor should it be difficult to build. So I see no reason to expect one of the CA guns to not function correctly when it comes to keeping a quality standard load in the subsonic level.

I have a CA89SD that I run with my Fleming Sear in an SEF pack. It was built up by Andrewski and has a re-timed hammer. The combination, in my case, works very well. And the Wolf ammo that I shoot through the gun is very quiet. I've examined the barrel porting and compared it to my dealer's factory HK MP5SD. They look just about identical.

I guess I was a little surprised that anyone would post what you did. With the exception of a few people who have had fake SD guns built with no porting on the barrel, I haven't heard a single story from anyone at all that they got a clone SD that was ported enough as not to keep their standard rounds subsonic. Have you personally had a problem with this, or heard of someone who has?

 

[Shattered Mind]

A ported barrel should drop velocities below supersonic... that's the entire point. If it doesn't, then you're running ++P++ ammo or some damn stiff custom reloads.

Nothing sarcastic in Dawg's response.

 

[Chopstix Kid]

Nothing sarcastic in Dawg's response.

+1. Takes a bit of getting used to, but after a while he's like that cool uncle you have that just says it like it is without a filter.

 

[axehole]

Good to know.

 

[kwesi]

A ported barrel should drop velocities below supersonic... that's the entire point. If it doesn't, then you're running ++P++ ammo or some damn stiff custom reloads.

Nothing sarcastic in Dawg's response.

The Dwag has definitely mellowed over the years.

 

[Shattered Mind]

The Dwag has definitely mellowed over the years.

He's an engineer. Management has that effect on engineers... sorta suck the creative blood out of them over time.

 

[kwesi]

Less than what? A gun with a 4-5" barrel? That would be a fair comparison. I'm guessing you used your K as a comparison. I'm going to have to consider doing that as well, just out of curiosity.

Retro: you raise a good question. I tested them in my Glock 17 @ 1222 then 1008 from the CA89SD.

 

[retrodog]

The Dwag has definitely mellowed over the years.

I thought the dawg was showing an overabundance of self control, considering he was responding to a person with a cat avatar.

:biggrin: