$35 DIY AR Trigger Job

[Droshki]

Cutting the hammer should actually prevent light primer strikes.

Since the JP springs are made to have less tension than stock springs, the hammer accelerates slower than it normally would, sometimes resulting in light primer strikes. When you bob the hammer, it removes mass which enables those lighter springs to accelerate the hammer faster than a stock hammer. It's all about force, acceleration and mass and a primer requires a sharp "strike" rather than a slow "push".

Think about it this way: Compare you (stock spring) pushing a motorcycle (stock hammer) to a kid (JP springs) pushing a bicycle (lightened hammer). You can both (for this instance) push your respective 2 wheeled vehicles at the same acceleration rate. If the kid (JP springs) were to try to push the motorcycle (stock hammer), it would accelerate much slower than them pushing the bicycle (lightened hammer).

Does that analogy make sense?

Well, being an engineer, I'm the kind of guy that wants to measure mass, spring constants, hammer acceleration, and resultant force of primer strikes, but really, if you all have empirical evidence that this works well (and I've no doubt that you do) then that's the most important thing.

 

[TennJeep1618]

Well, being an engineer, I'm the kind of guy that wants to measure mass, spring constants, hammer acceleration, and resultant force of primer strikes, but really, if you all have empirical evidence that this works well (and I've no doubt that you do) then that's the most important thing.

If you want to do the math, I'm all for it. I spent my first two years in college as a nuclear engineering major, but I switched for something less theoretical. Thinking back, I kinda wish I stayed with some sort of engineering.

 

[Droshki]

It would be interesting, especially since we used to have a girl at work with a Masters in Explosives Engineering. Im sure she would have had some input

 

[JohnAL]

That's why us electrical guys say "just put in a bigger fuse".

 

[FrankT]

I think this is why after market triggers/FCG are made so people don't make mistakes and mess up a good platform. They run from $40-300 you chose what you want, I would suggest you choose one to install if nothing but for safety and reliability.

 

[jogan]

so far, after this mod, I've not had one single issue with my rifle. I was a bit skeptical at first, but after a few carbine matches and about 600 rounds, no problems. And I DID bob my hammer.

 

[JohnAL]

are made so people don't make mistakes and mess up a good platform.

Yahoos with Dremel tools keep gunsmiths in business.

 

[Dan1612]

Can we make this a sticky? I had a hard time finding it and I was about to order the parts, and they ran out of screws from the time I went on to the time I went to check out. It'd be easier to find that way. Thanks!

 

[TennJeep1618]

Can we make this a sticky? I had a hard time finding it and I was about to order the parts, and they ran out of screws from the time I went on to the time I went to check out. It'd be easier to find that way. Thanks!

Done.

BTW, you can use a set screw on top of the grip screw instead of the Joe Bob's trigger adjust screw.

 

[Dan1612]

Great! Also, what did you polish the surfaces with?

 

[TennJeep1618]

Great! Also, what did you polish the surfaces with?

I used a dremel felt wheel with polishing compound

 

[Dan1612]

Wait, what kind of set screw? I don't really understand the theory behind the screw, so I was just going to use the Joebob one.

 

[TennJeep1618]

Wait, what kind of set screw? I don't really understand the theory behind the screw, so I was just going to use the Joebob one.

Start here, if you have any questions, go back toward the beginning.

http://68forums.com/forums/showthread.php?43364-30-DIY-AR-Trigger-Job&p=515133&viewfull=1#post515133

 

[Dan1612]

Great. Thank you Sir! A set screw might turn it into a $20 trigger job

 

[TennJeep1618]

Great. Thank you Sir! A set screw might turn it into a $20 trigger job

Yep. I never even considered that when I first saw the JoeBob's screw.

 

[Calculated steps]

Great. Thank you Sir! A set screw might turn it into a $20 trigger job

By buying the screw with the set screw in it makes the job easier. Doing just the set screw its a bit of a pain. The first time I did it there was threwlock in on around every thing. An I had to get a shorter grip screw. I have both the screw an set screw if you want them, but no tap.

 

[coolbluestreak]

Sweet idea, I'm going to have to try this.
My dad and my wife will be using 6.8's for whitetail this year, Dad has never really liked the AR trigger pull but, after watching my brother and I knock down deer with our AR-10's for the last few years the bug has finally bitten him. I think when the 6.8's get here I'll give this a try?

Anyone try this on an AR-10 yet?

 

[JohnAL]

Joe Bob's has the adjuster screws on sale right now for $14.95 with the allen wrench included and if you buy 3 you get an extra $5 off of each set. It's cheaper to buy 3 sets than it is to buy two sets using the coupon code on the adjuster page.

 

[Hipower]

So now, "Bob" is your hammer, instead of your uncle! :rockon:

 

[ksenter]

tomorrow, I'm buying 3 JP spring kits, 3 JBO adjustable screws, 2 Odinworks mag extenders (1 FDE for my 6.8, 1 BLK for pistol), and getting a free t-shirt from JBO over $100 order.