Yet another light primer strike issue w/ LL - Page 1

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[ARCHIVED THREAD] - Yet another light primer strike issue w/ LL

Posted: 9/28/2014 5:43:53 PM EDT

My 10.5" PSA upper w/ LL works flawlessly w/ H3 buffer and new hammer spring.
Here's the upper I've on now: http://www.karrisguns.com/catalog/product/8de60d74262549dca917336647a7cd21

However, I purchased a new 7.5" upper and took it out to the range today and also expected same flawless permanence.
Unfortunately, every fire was ended up w/ single fire & light primer strike.
The gunshop employee tried it w/ his 7.5" upper w/ H1 buffer and same light primer strike.

Should I change out the buffer to say...H2 or MGI?
Or perhaps, I need a new (again) hammer spring.
Even my new MP5K clone wasn't running 100% w/ my sear today... bad day

Any thoughts?

Posted: 9/28/2014 11:52:06 PM EDT

[#1]

You should use a new, different paddle with each upper, as each upper might require different timing and it prevents excess wear on a paddle by swapping it between different uppers. First time a paddle is fired with an upper carrier combo it forms to that combo and use with other uppers can rebend it each time leading to metal fatigue and accelerated failure.

Posted: 9/29/2014 11:17:04 AM EDT

[#2]

I will try with a new paddle.

I'm going to take it out today and see what happens...

Posted: 9/29/2014 12:29:52 PM EDT

[#3]

i would go with heavier buffer to my link like h3 and up in all my carbine length systems. keep in mind that the sp 1 cut carrier is 1oz lighter then a normal bcg so you have to account for that especially with shorter barrels

Posted: 9/29/2014 3:15:56 PM EDT

[#4]

Thanks for your advice, Circuits & MMS2!

Unfortunately, I used a new std paddle and still no go.
I was using H3 buffer, new hammer spring and also new std paddle but it seems like the timing isn't right.
It fired perfectly on semi-auto, so I know it's not a gas port problem.

When I half-cocked the gun in full-auto position the trigger is dead or wouldn't reset.
If I also half-cocked the firearm in semi-auto I sense small trigger movement (not sure if that calls a "reset").

What size paddle do I need to get and where to find one?

Posted: 9/29/2014 3:23:28 PM EDT

[#5]

are you using modified 3rd burst internals?

to be honest i didnt like how that selector wore on the bottom of my link and since i never used semi i switched back to just plane old ar-15 group.

since then my link has been absoultly reliable... before then i had all kinds of problems

Posted: 9/29/2014 3:32:13 PM EDT

[#6]

Hmm... might try that but still like to have semi option.

Yes, I'm using Joe's modified burst group.
For selector marking, I just taped up the center of LL body w/ electrical tape and never see another marking on it.

It still works flawlessly w/ cheap 10.5" PSA upper but not w/ my new 7.5" upper....

Quote History

Quoted:
are you using modified 3rd burst internals?

to be honest i didnt like how that selector wore on the bottom of my link and since i never used semi i switched back to just plane old ar-15 group.

since then my link has been absoultly reliable... before then i had all kinds of problems

View Quote

Posted: 9/29/2014 3:46:59 PM EDT

[#7]

Quote History

Quoted:
Unfortunately, I used a new std paddle and still no go.
I was using H3 buffer, new hammer spring and also new std paddle but it seems like the timing isn't right.
It fired perfectly on semi-auto, so I know it's not a gas port problem.

When I half-cocked the gun in full-auto position the trigger is dead or wouldn't reset.
If I also half-cocked the firearm in semi-auto I sense small trigger movement (not sure if that calls a "reset").

What size paddle do I need to get and where to find one?

View Quote

I'm not familiar with any half cock positions in an AR FCG, be it auto or semi, so I've got no idea what you're talking about there.

As for the paddles, have you measured the carrier gap on your working upper and on the non-working upper. If there is a significant difference in the gap, then you'll want a different thickness paddle to adjust for the difference in carrier gap on the uppers.

Posted: 9/29/2014 3:54:55 PM EDT

[#8]

Thanks Circuits, I will try to measure the gap and go from there.
Any place to order a new paddle w/ specific size?

My apology about my novice description.

I was trying to describe this timing procedure:
With the link in the rifle, hold the trigger back and cock the action, then slowly ride the cocking handle all the way forward/closed.
The hammer should not release. Then while still holding the trigger back, pull the cocking handle back 1/2", then release and let the carrier slam forward.
The hammer should be released.

Quote History

Quoted:

I'm not familiar with any half cock positions in an AR FCG, be it auto or semi, so I've got no idea what you're talking about there.

As for the paddles, have you measured the carrier gap on your working upper and on the non-working upper. If there is a significant difference in the gap, then you'll want a different thickness paddle to adjust for the difference in carrier gap on the uppers.

View Quote View All Quotes

View All Quotes

Quote History

Quoted:

Quoted:
Unfortunately, I used a new std paddle and still no go.
I was using H3 buffer, new hammer spring and also new std paddle but it seems like the timing isn't right.
It fired perfectly on semi-auto, so I know it's not a gas port problem.

When I half-cocked the gun in full-auto position the trigger is dead or wouldn't reset.
If I also half-cocked the firearm in semi-auto I sense small trigger movement (not sure if that calls a "reset").

What size paddle do I need to get and where to find one?

I'm not familiar with any half cock positions in an AR FCG, be it auto or semi, so I've got no idea what you're talking about there.

As for the paddles, have you measured the carrier gap on your working upper and on the non-working upper. If there is a significant difference in the gap, then you'll want a different thickness paddle to adjust for the difference in carrier gap on the uppers.

Posted: 9/29/2014 6:32:02 PM EDT

[#9]

Gap is .027

Posted: 9/29/2014 6:47:47 PM EDT

[#10]

Are you using the same bcg for both uppers?

Posted: 9/29/2014 6:52:44 PM EDT

[#11]

Yes, same BCG modified by Joe.
Gap is .025 w/ upper that works flawlessly.

Quote History

Quoted:
Are you using the same bcg for both uppers?

View Quote

Posted: 9/29/2014 9:21:51 PM EDT

[#12]

.027 with the thin paddle should work just fine no functional diffrence then .025.

I'm going with bolt bounce try the mgi buffer you mentioned above if you have one... The tell tail sign is that it works fine when on semi that's my 2 cents

Posted: 9/29/2014 9:32:14 PM EDT

[#13]

I've to buy one... it's just damn expensive and no guarantee if it actually works or not.
Hmm... really lost clue on this issue.

Quote History

Quoted:
.027 with the thin paddle should work just fine no functional diffrence then .025.

I'm going with bolt bounce try the mgi buffer you mentioned above if you have one... The tell tail sign is that it works fine when on semi that's my 2 cents

View Quote

Posted: 9/30/2014 7:49:00 AM EDT

[#14]

if you dont already have one i dont know that i would buy that vs just a 9mm or one of slashes buffers...... im out of ideas sorry
but hammer down and light primer strike to me screams bolt bounce...... expecially sine the fcg works with other uppers just fine.

Posted: 9/30/2014 2:26:41 PM EDT

[#15]

Thanks MMS2!
I'm really lost on this issue...
Going to try with new buffer... Thanks for your help bud!

Quote History

Quoted:
if you dont already have one i dont know that i would buy that vs just a 9mm or one of slashes buffers...... im out of ideas sorry
but hammer down and light primer strike to me screams bolt bounce...... expecially sine the fcg works with other uppers just fine.

View Quote

[ARCHIVED THREAD] - Yet another light primer strike issue w/ LL

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