SIG556 and 751 Sear/Hammer

(9 customer reviews)


In stock


Upgrade kit to give match trigger performance with tighter and smoother pull, and a glass sharp break.  Competition trigger performance on a combat rifle.  Fits all SIG rifles in the 55x series, including the 550, 551, 553, 556 classic, 556R, and the latest 556XI revisions.  It also fits the 751.  I *think* it will also fit older 510, 543 and 547, though has not actually been done yet.

Kit includes:

New hammer, sear, and sear spring.  All parts are ‘drop-in’ with zero modifications.

Key benefits:

– A true 2-stage trigger.  ‘Pre-first stage slack’ in original trigger is eliminated.

– Exceptional butter smooth trigger pull with no gritty feel or break-in needed.  Hammer and sear are pre-polished for smoothness, and hard coated for low friction and durability.

– Reliable performance, even in dirty conditions.  Grease is optional.  Hammer and sear have an advanced low friction surface coating that does not need lubrication, which might attract dirt.

– Hammer and sear are machined from billet plate tool steel (not cast), and full depth heat treated.  High quality steel holds sharp sear edges that will ‘break like glass’.

– Smoother feeding.  Low friction coating on hammer reduces hangup with bolt carrier.  Latest XI modifications are included to make the ‘hammer hang-up’ issue disappear.

– Long life.  Sear edges are oversized, reducing load, for years of match grade performance.

– Installation by gunsmith or armorer is recommended to adjust second stage sear engagement (pressure plunger behind trigger), but should take 20 minutes or less.

– Compatible with entire line of 55x rifles, including 556, 556R, 556XI, and 551-A1, 550, 551, 553, 751.

– Made in the USA.  Sear and Hammer count as 2 parts towards 922R compliance.

NOTE CHANGES TO THE POSTED INSTRUCTIONS. This Gen II design is 556XI compatible:

1. It no longer includes the hammer spring.  Instead the SIG hammer spring is re-used.

2.  It no longer includes the teflon spacer.

3.  The sear spring is now used IN ADDITION TO the SIG sear spring.

The included instructions have been modified to reflect these changes, however the posted pdf guide and the website pictures have not been updated yet, so there might be some differences versus what is presented.

SIG 556 Trigger Install

SIG Warrranty and Terms

RPS Trigger Video

9 reviews for SIG556 and 751 Sear/Hammer

  1. P. Ott (verified owner)

    I purchased a new SIG 556XI chambered in 7.62×39. The rifleis great, the trigger was horrible! Extremely difficult to get adjusted to. Contacted Shooting Sight and questioned the trigger enhancement kit. Art is extremely knowledgeable and explained the benefit. I purchased and installed. Wow, what a incredible difference!! Completely turned trigger and rifle into a amazing rifle.

  2. Bret (verified owner)

    Installed Sig556 RPS Sear/Hammer in my 7.62×39 chambered Swiss Arms 553R for sec922(r) compliance purposes. This set feels/works every bit as good or better than the original Swiss made parts. Since it worked so well, I decided to install another set in my 7.61×51 chambered Swiss Arms 751 SAPR. The result was the same, perfect fit and performance.

  3. John Long (verified owner)

    Amazing difference!
    My 556r was relegated to sitting in the safe as the sloppy factory trigger took all of the fun out of shooting the rifle.
    I ordered the improved trigger group from Art after speaking with him on the phone about my concerns. Art is a great guy and set me at ease about making the purchase. My local gunsmith performed the instillation and I couldn’t be more please. The trigger breaks clean and makes each shot a joy! Thanks Art for a very much needed quality product! 5 Stars!

  4. Craig Stensrud (verified owner)

    The trigger on my 556 was crap. It a lot of pre travel very very gritty feel and a lot of over travel. After installing this trigger kit and adding some small washers on the plunger behind the trigger it fixed the trigger issues. Like a different gun. Very easy install.

  5. Esteban Lopez (verified owner)

    This upgrade was definitely worth the money, the trigger is smoother. My 556r built is much better because of it.

  6. Mike C (verified owner)

    Worth the $$…transformed a closet queen into a viable RDS competition rifle…added the #6 washers to reduce overtravel…very happy I purchased this kit…

  7. Mark Gonzalez (verified owner)

    I installed this trigger upgrade into my sig 556 that had the most horrible trigger pull. The installation for me was a little tricky but it turned out awesome after final adjustment. Trigger now has no creep and is a true two stage that breaks like sex and now complements this exquisite rifle. Like to see future products for this rifle from shootingsights like improved rear sight group.

  8. Richard Singh (verified owner)

    Sig P556 now acts like a true 2 stage trigger. With the stock trigger and sear it felt more like a 3 stage trigger. This upgrade made a huge difference and I strongly recommend it. Trigger pull is lighter and breaks more smoothly. Shootingsight was great to deal with and shipped it out right away.

  9. Dave (verified owner)

    About a year and a half ago now I installed this trigger in my 556xi. Not only did the extra disconnect spring fix the hammer follow issue the oem triggers have, but this new trigger performs fantastically. Luckily not much pre-travel, super solid and crisp break with no creep whatsoever, and a rather short reset. I was able to shorten the over travel with a couple #6 washers and now I have a trigger that’s easily capable of landing consistent accurate shots. I’ve got many compliments with at least two people remarking how the gun feels like a tac driver. If you have one of these rifles, just buy the trigger. You will not regret it.

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