I don’t think so. The o-ring doesn’t form any more of a seal than was already present just from the boot. Also even without the retaining ring the switchboard is still held very firmly in position by the tailcap and body tube.
Also the switch was still fully responsive. The light still clicked on or off every time when the switch was pressed. I just couldn’t ramp up or double click to turbo.
Removing the tailcap retaining ring solved the problem completely. And my ring did look a little worn.
Solution to light occasionally malfunctioning after battery changes
I finally figured out what was causing the problem where after battery changes, sometimes the light would only activate in low mode.
Apparently, I overtightened the switch retaining ring after modding. Doing so lifted up at least part of the board a tiny amount away from the tailcap. This sometimes caused a poor connection between the edge of the switch board and the tailcap. The light only turned on in low mode because of this poor connection.
The best solution is to not overtighten the retaining ring when modding. I did this by tightening it all the way, then loosening it by maybe 15 degrees.
Alternatively, removing the retaining ring also works. However, that causes the switch parts to risk being lost if you ever unscrew the tailcap.
Nubbin mod is not necessary
On another note, my second KR1AA arrived. This time, the only switch mod I did was to add a 9mm od by 1.5mm thick o-ring between the switch boot and the switch board. I didn’t touch the nubbin. The result is quite satisfactory. It is not necessary to remove the nubbin at all.
I don’t have any on-hand, but I expect using an even thicker o-ring would provide even more resistance.
Glad everything is working 
a 9mm od by 1.5mm thick O ring w no change to the nubbin sounds nice and easy!
now that you have two KR1AA, congrats!, can you share any info on which LEDs they have, and if there is any significant difference in beam spread and throw, due to the LED choice?
19mm outside dimension for the o-ring is much too big. The o-ring needs to sit inside the pocket or cup of the button boot. 9mm outside dimension is just right. I also tried 10mm, but that was too big.
My first came with FFL5009r 5000K 98 cri, which I replaced with NTG50 5000K. My second came with SFT70 5000K. The beam pattern is floody with both, but slightly tighter with SFT70.
Of these emitter choices, NTG50 looks overall the best due to tint superior to the FFL and CRI superior to the SFT.
thanks for your 5000K FFL, NTG, and SFT70 LED comments
I think only the 3000K SFT70 is High CRI.. Im debating that option, as well as the NTG50 4200K, when I finally get to order a V2 KR1AA
Good choice. I think I’d probably go with SFT70 3000K over NTG if I liked warm color temps. However, I currently prefer around 5000K so that’s what I went for.
Unfortunately low CRI SFT70 does not compare well to beautiful high CRI NTG50.
More beam shot pictures please, if anybody can that’s got a few of these now!
Hello Jon my DA1K with NTG50 4200k arrived yesterday. I turned it on to make sure it works, did a quick shootout with Fireflies 351a, 519a 5700 DD, and B35AM then wrapped it up to go under the tree. So no number, no measurement… but you know where I stand w/ tint-snob LEDs.
Pardon me if you already have one, otherwise IMHO I would forget everything else just get it ASAP. It’s a ground breaking LED and very beautiful (a little more rosy than B35AM, not so rosy as FFL351a if I must say something out of that quick shootout).
Congratulations! 
I believe you are absolutely right!
Thank you for your support and encouragement.
I have an NTG35 4200K and I believe it is the undisputed successor to my beloved sw45k D200.
Fundamentally is somewhat a soft press button, with less feedback than rubber button.
The important aspect is how you use your thumb to press the button, if you use the tip of the nail/tip of the finger to press on it then the action of the button is poor, especially if pressed towards the sides of the button with your nail/tip of the finger, if you use the belly of your thumb then it’s great.
Thanks.
Probably the best answer for me, would be to get Two KR1AA..
one SFT70 3000K, and one NTG50 4200K..
Im considering the Raw Aluminum body.. what do you think of that option, and which body colors did you choose?
Did your lights come with the metal rings intended to be used if the clip is removed?
I’m not that guy but I’m going to order the SFT-70 3000K next.
I didn’t get the raw one, but mine did come with the clip delete spacer ring. also the standard extra set of body orings, but no body color bezel because I got it from Jackson and he doesn’t seem to include the extras, from my experience. I just got the bronze ss one.
OT. Jon the funny thing is I am thinking of collecting more 219b 4500k lights such as Convoy S21D and M21H. One reason is, I believe I have most if not all tint snob LEDs, but still NOTHING looks like 219b sw45k (different, not better). I am sure you know exactly what I’m talking about. 
The other reason is I don’t know why, but Simon appears to have crossed out the 219b 4500k bare LED on his web page. As OCD a flashaholic as I am, this could only mean one thing, BUY NOW. AFAIK he’s the last vendor who has this LED. When he runs out, it’s over.
IF I can remember (on no sleep currently) I can try to get some type of beam/wall shots of my FL5009R 4000K KR1AA.
People are saying the NTG50 and FL5009R are basically the same emitter, so I’d guess they’d be nearly identical in beam pattern, just different in tint?
I have a NTG50 4200K, but haven’t put it into a light yet. I’d like to see the difference but it’ll likely be under a reflector or an LEDiL OLGA TIR which could change the DUV relative to the KR1AA optic.
crossed out the 219B 4500K bare LED
this is extremely unfortunate. I was late to the game and didn’t get into lights until after the 519A released, but 219B 4500K has become my favorite emitter.
I ordered from Simon in May and I thought I had ordered 10-15 SW45K, but apparently I only ordered three. I’m going to have to try to get more.
FWIW, ILLUMN still has in stock 219B 4000K (D200), which are also pretty nice and a bit rosy, but they still aren’t like the SW45K.
I might have to try to order an M44 or D4S mule with them from Jackson if he has enough.
thanks for commenting, I look forward to your first hand impressions
after further research, Im still undecided about SFT70 3000K, and just added NTG50 2700K to my list of possible warm options..
arrows on the DUV and LED model: (I dont usually like tint at the bbl, I prefer below, heavily influenced by sw45k of old)
Im afraid its already over because the more rosy D200 bin has been gone for a long time. All Ive seen lately are the less rosy D220, which look slightly greenish by comparison.
This is why the NTG 4200K is on my radar.. it has the rosyness of older sw45k
but I already have mostly sw45k lights, and only two 219b 3000K lights (that I wish were more rosy) .. so Im shopping for a Warm KR1AA, for use at low outputs as an indoor and nightstand light..
Since I prefer rosy, NTG50 2700K seems like a better option for my intended indoor use at low outputs, than SFT70 3000K..
Agree but also 519A 5700 dedomed are so good
I love DD 519a too
But 519a are not an option for KR1AA…
I like 519a 5700K dedomed. I had them in probably 15 plus lights.
However, I’ve since replaced most of them with NTG35 5000K.
NTG is just better in every way.
