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12/29/2025 1:57:42 AM EDT
[Last Edit: 1stID][Edited]
I have a SF X300 in the A, pull down tab to unlock config.  I much prefer the B version ,with the lock screw.

Can I buy this kit, and convert the A to the B:

https://www.primaryarms.com/surefire-x300u-b-mount-parts-kit-black
12/29/2025 2:33:02 AM EDT
[#1]
Nope.
12/30/2025 9:29:38 AM EDT
[#2]
The X300's have good resale value.  Suggest selling your "A" on the EE for $180'ish and buying a "B" Turbo for $219.
3/12/2026 7:52:59 AM EDT
[#3]
Why do you "much prefer" the B version? I would never own a B over an A because the only thing that is even sometimes better for the B IMO is how rigid the light fits or the lack of effort to get the A to be tight and rattle free. There are fixes for that. But to swap out the ability to quickly pop the light off and on is just not worth the effort saved to get solid lockup on the A. You might as well just get a Streamlight at that point.
3/13/2026 7:02:52 AM EDT
[#4]
Quote History
Originally Posted By Eric_T_Cartman:
The X300's have good resale value.  Suggest selling your "A" on the EE for $180'ish and buying a "B" Turbo for $219.
View Quote


I’d go this route.   The turbo are awesome
5/4/2026 2:41:02 AM EDT
[#5]
Quote History
Originally Posted By DevL:
Why do you "much prefer" the B version? I would never own a B over an A because the only thing that is even sometimes better for the B IMO is how rigid the light fits or the lack of effort to get the A to be tight and rattle free. There are fixes for that. But to swap out the ability to quickly pop the light off and on is just not worth the effort saved to get solid lockup on the A. You might as well just get a Streamlight at that point.
View Quote


I have problems on several of my pistols getting the A version off.  On my FN FNP 45, it was very difficult to take off, and once on, there's no real way to pry it off.  I've had to slap the bottom of the sight to use impact force to get it off.  

The B version to me is the happy medium between the quick on/off (maybe maybe not, and with some rattle on some guns) of the QD A, and the more solid mount of the A version that uses the set screw and locking bar.
7/22/2026 3:54:41 AM EDT
[#6]
If the light is not going in far enough back and you had to force it did you swap the plates between P and U?

If it is just too narrow on tbe rail did you unscrew and adjust the width and rescrew the rail grabbers?

If it is still not fitting front to rear did you grind/remove the tab that limits fore/after travel?

I have always had one of these allow a nice fit if too tight on the A model.
8/27/2026 10:31:34 AM EDT
[#7]
Quote History
Originally Posted By 1stID:


I have problems on several of my pistols getting the A version off.  On my FN FNP 45, it was very difficult to take off, and once on, there's no real way to pry it off.  I've had to slap the bottom of the sight to use impact force to get it off.  

The B version to me is the happy medium between the quick on/off (maybe maybe not, and with some rattle on some guns) of the QD A, and the more solid mount of the A version that uses the set screw and locking bar.
View Quote View All Quotes
View All Quotes
Quote History
Originally Posted By 1stID:
Originally Posted By DevL:
Why do you "much prefer" the B version? I would never own a B over an A because the only thing that is even sometimes better for the B IMO is how rigid the light fits or the lack of effort to get the A to be tight and rattle free. There are fixes for that. But to swap out the ability to quickly pop the light off and on is just not worth the effort saved to get solid lockup on the A. You might as well just get a Streamlight at that point.


I have problems on several of my pistols getting the A version off.  On my FN FNP 45, it was very difficult to take off, and once on, there's no real way to pry it off.  I've had to slap the bottom of the sight to use impact force to get it off.  

The B version to me is the happy medium between the quick on/off (maybe maybe not, and with some rattle on some guns) of the QD A, and the more solid mount of the A version that uses the set screw and locking bar.


I'd rather the A that's annoying to remove than the B that removes itself.

Solution B is to buy more lights.
8/30/2026 10:55:13 AM EDT
[Last Edit: ScoutH57][Edited] [#8]
Both A and B come with different Cross bars in the box.

the A also has the sliding lock thing you can convert and adjust tension.


The Bs are just fine, if you use something besides your thumb to tighten it


Can’t really go wrong with either. The newer Turbos are rad.

I have 2 X300Us that I’ve had done a lot of things not recommended by the manufacturer with involving windows and meat and they keep chugging along

I have a couple more Bs than As cause they are a little simpler for mounting on Carbines and or other non gun stuff.

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