View Full Version : Trigger not cutting it on my AR10 build, HELP needed

10-30-2010, 1:45 PM
Thanks for looking guys and trying to help me solve this problem. I built the gun two weeks ago and still havent been able to fire a shot.
The build included a JARD trigger with a 2lb pull spring. After getting the trigger set up PEREFCT! The the will only ping a primmer. The mark is there, but very light!
I THINK the problem is the hammer spring. It seems to be tooo light to handle the .308 round. Ive tried called JARD but I get what sound like someones house machine.
Anyone have any advice?

10-30-2010, 3:18 PM
is an AR15 hammer spring lighter than a 10? maybe they sent you one of those?

10-30-2010, 3:40 PM
I think thats it, I would like to know the answer to this question also.

10-30-2010, 4:15 PM
I think thats it, I would like to know the answer to this question also.

do you have a 15 to compare it to? are they dimensionally the same?

10-30-2010, 4:47 PM
No, I was going to try the AR10 spring that comes with the ower DPMA parts kit. But the spring is too big to use with the JARD kit. The trigger wont work with it installed.

10-30-2010, 5:07 PM
Are you sure your firing pin is long enough? Is the firing pin retainer pin in front or back of the pin stay? If you put the retainer pin in the wrong place the firing pin wont hit the primer correctly. Push your pin all the way with your finger it should protrude out the bolt face about 1/16th of an inch.

10-30-2010, 6:47 PM
If you have a stock ar15 trigger just swap that in and try it, the jard might be hitting too light.

10-30-2010, 8:31 PM
Im about to just put the stock DPMS trigger in for now and see what happens. Can I put the bullet dump the powder and test a round? I hate having to drive to the range when doing work like this.

10-30-2010, 9:07 PM
I could have been misinformed but the ar 15 trigger is what is used in the ar 10s. There are only a few different parts between the two FCG's.

10-31-2010, 5:18 PM
Put the stock trigger in and it works fine. Looks like I need a stronger hammer spring.

10-31-2010, 6:42 PM
From what I've read, the AR10/SR25 need a stronger hammer spring for the .308 round. That is why JP Enterprises suggests a heavier spring set to safely ignite the primer EVERY time.

10-31-2010, 11:29 PM
Do you reload what primers are you using AR's are prone to Slam firing although its never happened to me I would only be worried about match type primers.

Nathan Krynn
11-01-2010, 10:10 AM
You can't use an AR-15 match trigger with the .308, like others have said the springs are too weak. You need one rated for .308.

11-01-2010, 12:15 PM
Put the stock trigger in and it works fine. Looks like I need a stronger hammer spring.

FWIW mine has the RRA 2-stage and works great - breaks light but still hits plenty hard enough.

I would not go lighter than ~3lbs.

11-01-2010, 1:03 PM
Talk about service. I called the number on the site again and someone answered. I told them the problem and they are sending me a new hammer spring no charge. So Ill have a update soon! Im happy because the trigger overall felt great!

11-01-2010, 4:00 PM
I recently built a .308 AR and accidentally put the hammer spring in backwards and had the same problem. It would fire 2 out of 3 rounds, but all were light hammer strikes.

Took my AR-15 out of the safe and compared parts and noticed that the standard hammer spring assembly that came with my DPMS lower parts kit is much larger than the RRA, 2 stage that is in my AR-15.

Flipped the spring around and all is well now.

Eventually, I want to switch out the stock DPMS trigger for something that is more crisp.

Let us know how this works out for you.



11-01-2010, 11:15 PM
I use a chip mccormick ar15 super match in my ar10 build. Never had a problem with light primer strikes.

11-02-2010, 11:29 AM
JARD makes at least 3 triggers that one could use in an AR-10. THey make their standard AR-15 trigger which will fit and mostly function in some AR-10s. They make that same AR-15 trigger with a heavy hammer, which is supposed to more reliably ignite .308 primers. And finally they make an AR-10 specific trigger with a special narrow hammer for early model AR-10s that presumably have a narrower than normal slot in the bolt carrier for the hammer.

I am using the AR-10 specific trigger in my DPMS even though it is not what JARD would normally recommend for that application. I got the trigger by accident (I had a bunch of websites open simultaneously and ended up ordering the from the wrong site), but I like the fact that it has a lighter hammer (theoretically faster lock time). I have never had a failure to fire with my setup, on a pretty large variety of ammo, including surplus. I did notice that the JARD hammer spring seemed lighter than the stock DPMS spring, but it could just be a different alloy that is stiffer so it can be thinner.

So, the problem may be that you have the narrow hammer slot bolt carrier but you are using the wider hammer meant for newer AR-10s and LR.308s or AR-15s. It could be that you are using the light hammer AR-15 trigger but you should be using the heavy hammer. It could be that the spring is in backwards as someone else already mentioned, or you could just have a bad spring. I have communicated with JARD by email, and got a reply fairly quickly.

11-02-2010, 11:52 AM
They took care of it. They are a stand up company that asked no questions. I told them the problem they then asked what my address was. Great service.
Ill be buying a trigger for my AR15 after this from JARD. You just cant seem to find this kind of service anymore.
As for the trigger, the hammer spring was installed both ways in a attempt to try and resolve the problem, it didnt.
Im willing to bet money that the new spring will fix it. Ill post a follow up soon.

11-09-2010, 8:55 AM
Got my new spring and the trigger works perfect! Very nice feel to it. The difference in the two springs was day and night. Thanks again to all that helped and a big thanks to JARD for sending a extra spring on their dime.

11-09-2010, 11:21 AM
Glad to see you got your gas block and trigger situation fixed. Now we need to see some pic's


11-09-2010, 2:50 PM
Now we need to see some pic's

Here you go........... http://308ar.com/trigger/Jard%20AR-10%20LR-308%20AR%20Trigger.jpg

11-09-2010, 3:23 PM
Here you go........... http://308ar.com/trigger/Jard%20AR-10%20LR-308%20AR%20Trigger.jpg


11-09-2010, 4:23 PM

11-09-2010, 4:41 PM
What's the barrel length?

11-10-2010, 8:53 AM
18 inches
BTW if anyway wanted to know this brake is insane! Very loud and you can see the gasses come out the sides. I love it,lol