The Modular Driven Technologies (MDT) TAC21 chassis system allows bolt action rifle users enhanced ergonomics and functionality by allowing a conventional Remington 700 (short or long action), Tikka T3 or Savage (short action) to use standard AR15/M-16 M4 type stocks and optical mounts.
In 2011, Rifleshooter.com was one of the first sources to review the Modular Driven Technologies TAC21 and TAC21LA chassis systems. If you’d like to read these posts, see:
Modular Driven Technologies TAC21 Chassis System Review (Initial Thoughts)
After three and a half years of continuous use of the TAC21, I decided to post some updated thoughts on the system. Currently, my original TAC21 is living on a custom Remington 700 chambered in 223 Wylde. This rifle started life as a stock J-lock Remington 700 in chambered in 223. We pulled the barrel, trued the receiver with the Manson System, and threaded and chambered a Shilen #7 select match 1:8 twist barrel (20″ finished length) with a Manson fixed pilot 223 Wydle reamer. This rifle uses the following components from Brownells:
- TAC21 SA system
- Shilen #7 select match barrel, .224, 1:8 twist
- Vortex Viper scope
- Magpul PRS stock
- KRG bolt lift
As you can see below, the rifle is quite a shooter. The combination of TAC21, Shilen barrel and the Manson 223 Wylde reamer worked out (the rattle can paint probably helped too). I’m shocked the 223 Wylde chamber shoots so well. Don’t hate fixed pilot reamers- they work better than most people think. This is the second rifle with a Shilen select match barrel I chambered with this reamer and both have been tack drivers. This rifle has both won and placed in a number of matches- not too shabby!
Here are some representative 5-shot groups at 100 yards.
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5-shots with an 80-grain SMK at 100 yards, .280″. From bench with bipod and rear bag.
5-shots with a 73-grain Berger at 100 yards, .147″! From bench with bipod and rear bag.
5-shots with a 75-grain A-Max at 100 yards, .337″. From bench with bipod and rear bag.
300 yard, 10-shot group with the 77-grain SMK, 2.077″ (.661 MOA). Fired prone from bipod with rear bag.
After almost 4 years around the TAC21 chassis, what are your thoughts on it?
- The TAC21 is capable of extreme accuracy. I’m still impressed by some of the groups the 223 shot with it. We’ve had it on a number of guns and accuracy has been the same or better in the TAC21. The system has never degraded accuracy.
- The ergonomics are great. It is a very comfortable system to shoot.
- Recoil is mitigated by bringing the stock in line with the barrel (just like an AR).
- The continuous top rail with 20 MOA taper allows integration of forward mounted night vision, such as the PVS-22.
- It is becoming quite popular- I can’t help but notice it popping up more and more. Some manufacturers and well known gunsmiths, including the Remington and Robar, offer factory rifles with the TAC21 system.
- It works well. The original rear stock adapter has been redesigned twice, both have been an improvement. Originally, it was a push pin (see Modular Driven Technologies TAC-21 Chassis System Review (Initial Thoughts)) and then a cam lever (see TAC21 Review (TAC21/TAC21LA)). The current design is a cam lever with locking tabs.
What are the downsides?
- You can’t use a Holland style lug with the system (unless you have at it with a die grinder- don’t ask). This isn’t a big deal unless you already had a custom rifle built with a Holland style lug- then you have a problem.
- Assembly requires removal of the trigger assembly. If you work on 700 triggers a lot this isn’t a big deal. However, if you don’t, this can be a little tricky.
- A bit front heavy with a collapsible stock on the system. The Magpul PRS balances it out nicely.
What are your overall impressions of the TAC21?
I really like the TAC21. In addition to offering enhanced ergonomics and recoil control, it increases the modularity of a bolt action rifle and adds a detachable magazine system. In the future I would like to see some different fore-ends offered (a KeyMod would be nice) and a way of installing the system without removing the trigger.
The TAC21 offers a bolt-action rifle users a solid performance upgrade with AR15/M-16 M4 stock interchangeability.
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