The “Kraken” Aluminum Lower for the Ruger® Mark IV™ 22/45™
The “Kraken” Aluminum Lower for the Ruger® Mark IV™ 22/45™

The “Kraken” Aluminum Lower for the Ruger® Mark IV™ 22/45™

Part Number:TK26N0419
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Your Price: $319.99
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At a Glance:

  • Cerakote finish (red cerakote will have a slightly different appearance compared to red anodized [TK] accessories)

  • Firmly anchor your barrel to the lower

  • Greatly increase lifespan and strength

  • Center of gravity decreases muzzle rise

  • Supports factory and aftermarket uppers

  • Every “Kraken” comes with an extended magazine release

  • Pivot kit now pre-installed in every lower as of November 24, 2021 (Pivot kit replaces factory Ruger® Frame Lug and is only compatible with the TANDEMKROSS “Kraken” Aluminum Lower)

NEW in November 2021

The “Kraken” Aluminum Lower now comes in four exciting colors! PLUS! TANDEMKROSS now carries ALL the internal components necessary to build a complete “Kraken” Aluminum Lower WITHOUT a donor pistol. Assembly is still required, but no more hunting for hard-to-find parts! TANDEMKROSS has everything you need for your build! Simply pick your favorite color “Kraken,” add a “Build Your Own Kraken” or “B.Y.O.K.” Kit with the drop-down option below, and you’re on your way!

The “B.Y.O.K.” Kit includes:
The TANDEMKROSS “Kraken” Aluminum Lower is a “stripped lower” designed to house the internal components of a factory lower in an all new, deluxe upgrade!

The “Kraken” is built to Last! This light and durable aluminum lower is highly heat and chemical resistant. Fully metallic means no more ripping thread inserts out of a plastic frame! The durable cerakote finish helps to prevent corrosion, improve performance, and reduce wear.

The “Kraken” features a textured back-strap for a more slip-resistant surface in all conditions. This in combination with larger, “hooked” trigger guard provides enhanced ergonomics for improved grip and control. The oversized trigger guard is also ideal for gloved hands!

Over time, the engagement between the receiver and lower of the pistol can lose its secure seating resulting in unwanted slack between the two components. We have removed the one button takedown in favor of a redesigned and upgraded takedown screw. This new, proprietary locking mechanism will improve the interface between the lower and receiver, creating a tighter and more secure fit. All this makes your pistol more reliable and dependable.

Anyone who has fully disassembled and reassembled a Ruger® Mark IV™ 22/45™ knows that the installation of the sear can be the most frustrating part of the process. The intuitive design of the “Kraken” makes installation of the sear simple with a sear retention hole; designed to allow the sear to be held in place with the included 1/16" allen wrench until the hammer assembly is installed.

We have also included an internal feature to limit how far the hammer can lean back. This ensures the hammer is never cocked over center, eliminating a common headache during installation.

The “Kraken” supports virtually all [TK] parts and accessories for the Ruger® Mark IV™ 22/45™. This lower will also host practically all aftermarket and factory receivers for the Ruger® Mark IV™ and Mark IV™ 22/45™.

With the new colors available for the “Kraken,” the ways to get #TANDEMIZED are limitless!

The “Kraken” Aluminum Lower for the Ruger® Mark IV™ 22/45™ is an absolute must-have for competitive shooters or just to MAKE YOUR GOOD GUN GREAT!

Supported Models:
  • Ruger® Mark IV™ 22/45™
  • Ruger® Mark IV™ 22/45™ Tactical
  • Ruger® Mark IV™ 22/45™ LITE
Don’t forget! All TANDEMKROSS products come with a no-hassle, lifetime guarantee!

Patent Pending

Important Notes

If intending to install Volquartsen Firearms internals:
  • The sear spacer will not be needed or used in the “Kraken” Aluminum Lower
  • Volquartsen Firearms has produced two versions of the sear for Ruger® Mark IV™ 22/45™. The “Kraken” will work with only the smaller of the two Volquartsen sears (measuring 0.3625"). The “Kraken” will not work with the larger of the two sears (measuring 0.4213"). If you do have the larger sear, please reach out to Volquartsen Firearms for options.
RETURNS: If you choose to add a “Build Your Own Kraken” or “B.Y.O.K.” Kit to your “Kraken” Aluminum Lower, no individual component is eligible for return unless for manufacturer defect. To return any individual component of a “Kraken” purchased with a “B.Y.O.K.” Kit for any other reason, the entire product must be returned in full.

INTERNATIONAL CUSTOMERS: Please note, because the “Kraken” Aluminum Lower is considered a frame, it is NOT available for international sales.

WARNING: This product can expose you to chemicals including chromium, which is known to the State of California to cause cancer. For more information go to
5 Stars
I would first like to thank Kevin for going above and beyond in customer service. I purchased the Kraken the first day it came out and I couldn't wait to try it out. The following weekend I took it out to the range and had major problems with the Kraken (spoiler alert it was my fault). I was really upset that I spent this much money on something that didn't work. I purchase the majority of my competition stuff for my 10/22 and Ruger from Tandemkross and never had any issues. I wrote a review giving this product 2 stars. The very next day Kevin reached out to me about my review. Kevin asked me how could he help and if I wanted to do a fully refund or I could send it in for his engineers to find out what the problem could be with the Kraken. I opted to send in the Kraken to Tandemkross. The amazing thing was Kevin's customer service and how he represents Tandemkross as a company that cares about their customers. I was provided updates and never wondered what was going on with my frame. Kevin called me up and told me they found the problem. I was so excited about taking the Kraken to the range I put on a part the wrong way. I couldn't believe I did that and through it all I received back my Kraken frame with some new parts installed. I'm really impressed on how the customer service at Tandemkross really works for the customer. I didn't have to pay for any of the shipping and I was also sent a free hat. I just recently took the Kraken to the range and fired over 100 rounds with 3 types of ammo. The Kraken exceeded my expectations on how the ergonomics work so well. I will be using this for my competition gun in the further. Thank you again Tandemkross.
Did you find this helpful?  11 of 11 Found Helpful
Reviewed by:  from St. Petersburg. on 5/27/2021
5 Stars
Exactly what I needed to complete the build
absolutely great frame with much tighter tolerances than the factory polymer frame. This is exactly what I needed to finish out my build. Everything went together as smoothly as possible for a Mark IV 22/45. The sear assembly is still just as infuriating as normal with the VQ sear, as it doesn't benefit from the hole in the frame that TandemKross put there. the sear and hammer spacers used with the VQ kit are no longer necessary with this lower due to the tighter tolerances. Paired this frame with an LLV upper and competition bolt from Volquartsen, TandemKross Victory Trigger, TandemKross grips, Striplin thumb ledge, and cornerstone safety. It's a killer setup and having the aluminum frame really completes the build in a way the factory polymer couldn't. Now it actually feels like a high end custom gun.
Did you find this helpful?  10 of 10 Found Helpful
Reviewed by:  from GRETNA. on 3/29/2021
5 Stars
Kraken Review
I wanted to wait till I had about 1000 rounds with it before posting my review. First off, this is a great upgrade from the stock frame. This frame is well ballanced and feels very nice in your hand. I have a smaller hand, but with G10 or stock grips, it is still very comfortable. The frame itself is very slick, in that it has no grooves or serations to aid in grip. This is an area I hope the next gen Kraken will inprove on. Installation of parts is straight forward and anyone with the right tools and some patience can get it done inside of an hour. If you don't already own a MKVI 22/45, sourcing all the parts is near impossible. Ruger will not sell you parts without a serial# and the main parts you need, you can only get through Ruger and you HAVE to send your gun in to have them installed by them. If you choose the victory trigger, you will find the the over travel screw is to short to be fully usefull. The VQ trigger however is perfect for this frame. This is the second area I hope is improved on. The addition of a removable trigger stop would allow you to use one of the small set screws to fine tune your trigger. The other parts like the forward thumb rest and safety fit and feel great on this frame. Magazines with or without basepads (VQ metal or TK bumpers) fit snug and secure and shoot out when ejected. The blast shield helps keep the mags lined up properly and prevents rocking back and forth. If you use the VQ accu kit, the blast shield will not fit on the hammer. With the VQ kit installed, you will notice the rocking in the magazine, but after 1000rnds, I have not had any failures. Upper lockup is probably my favorite part of this frame. You dont have to crank down on the screw to get a very tight fit between the upper and frame. This is a game changer for anyone who wants a target 22 pistol. I paired this frame with a VQ LLV-4 4.5 upper w/comp and at 25 yrds, it is a tac driver. Even with the lite upper, it is a noticeable difference with its accuracy. Final thoughts are, I would recommend this frame to anyone. At the price point, you will be around the same if you went with a VQ built frame, but in my oppinion, the Kraken is a much better feel and the lockup is far tighter. If Tandemkross continues to put out quality product like this, I will be a customer for life. Buy this frame and you wont be dissapointed.
Did you find this helpful?  8 of 8 Found Helpful
Reviewed by: (Verified Buyer)  from Pensacola, Fl. on 4/21/2021
5 Stars
Kraken takes a Mark IV up a level
This frame is great. I was skeptical about losing the one button take down feature but it makes sense and isn’t an issue. I can’t say whether the claimed change in CoG improves my accuracy but I can say that overall feel is a big improvement. It looks great and feels even better. I love the lip around the trigger guard. Note: if using a volquartsen accurizing kit, don’t install the tiny black washer/sear spacer and if using the hammer spacer, use the thinner one. This frame is held to tighter tolerances than the polymer unit it replaces so build it up as if you were doing a metal framed standard mark iv.
Did you find this helpful?  6 of 6 Found Helpful
Reviewed by: (Verified Buyer)  from Orlando. on 4/21/2021
5 Stars
Looks awesome with the black bull barrel as well as my bronze lite barrel.trigger pull is also a bit lighter 1.5 lbs was 1.8 Everyone I show my pistol is blown away at how good it looks .I love it
Did you find this helpful?  3 of 4 Found Helpful
Reviewed by:  from Idaho. on 4/16/2021

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