It's a non issue really, I can't see anyone asking for warranty or trying to claim liability on something they had modified after purchase.
Even if they did, there is no legal recourse/ground to stand on.
The problem is that even when the manufacturer is above any legal reproach they get dragged in to a legal action as a matter of course, that is pretty much SOP for lawyers today.
Case in point we got dragged into a legal action a few years ago when a fellow blew his leg off and killed his T.V.. The total exposure that ATRS had was re-blueing a bolt action rifle. ATRS test fired the rifle when it was final assembled after being blued and there was no issue at all until several years later.
ATRS had no part in the victims drinking and drug intake nor did ATRS load the rifle illegally inside the apartment where this occurred. At no point was ATRS ever in the apartment, nor did we supply ammo or point the rifle or force the rifle to be pointed at the victims T.V. while his leg was in the direct path of the bullet. Being as ATRS was never in said apartment it can be concluded that ATRS did not pull the trigger, so could in no way be held responsible for the rifle blowing off the lower leg of the person who was in possession of the rifle at that time or the T.V. that was killed.
Responding EMS and police found various hand tools and ammo scattered around close to the victim, the reason for these tools and assorted ammo remain a mystery to this day. How the rifle came to be in the possession of a person with NO PAL is also still a mystery, but the fact remains the victim was in sole possession of the rifle at the time of the occurrence. The suit was dropped after the victim committed suicide 2 years after the incident.
HOWEVER It still cost ATRS many thousands of dollars defending itself to point out the obvious.
We have to look at many factors before making a decision to do something. In the case of 300 Blackout, we looked deeply into the number of catastrophic failures that have been reported when guys try and run sub-sonic ammo out of long barreled rifles. There "were" several bolt actions being offered, but it seems even they are no longer offered, and the chances of a gas gun failing are mush higher than a bolt gun where ALL the gasses are exhausted out the muzzle.
We concluded that the incidence was significant enough to NOT offer this.
We have also looked at the failure rate of bolts for the 6.5 Grendel and 7.62x39 and decided we did not want to have the hassle associated with warranty claims given the high incidence of failure that cartridges have in an AR style platform.
IF it the AR10 bolt could be employed, it would be better suited to the larger boltfaces these cartridges require,however it is a different platform.
It is all well and fine for a huge conglomerate to "walk on the wild side" when it comes to questionable combinations. They have REALLY deep pockets and can easily ward off, or buy out lawsuits, and due to their volume of sales having a few hundred upset customers means nothing, either to them or the client base. A small manufacturer such as we are can not afford the litigation, nor a bad name in the minuscule market Canada has.
This is also part of the reason that only complete and tested rifles or uppers are being sold, as opposed to DIY kits.