BR99: non-standard rail?

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Odd Job · #1 Post by **Odd Job** » Sat Mar 14, 2015 7:47 pm

I have been sorting out my BR-99. Got a new charging handle, a Yankee Hill Machine riser and a Burris Fast Fire III with the Flat top mount. These are the components:

http://yhm.net/scope-riser.html

http://www.opticsplanet.com/burris-ar-f ... mount.html

The Yankee Hill Machine is a good, precision riser. I have one already on my SIG522 which has a Picatinny rail integrated in the receiver just like the BR99. This riser is one piece of metal.
I have the Burris and the Flat Top mount currently mounted on that SIG522 whilst I wait for a second Burris Fast Fire III to arrive from Optics Planet.

I already have the second Yankee Hil Machine riser and I have checked it on the SIG522, it is an exact fit, just like its brother.

So...imagine my disappointment when I tried to put the Yankee Hill Machine Riser on my BR99 and it won't go on. It doesn't just slide on, as it will on the SIG. It can can be made to fit but it requires persuasion with a rubber mallet.
When the riser is on, the screws cannot be inserted because they contact the bottom surface of the groove in the rail on the BR99.

When I compare the BR99 rail with the Yankee Hill Machine Riser, the spacing of the grooves is identical, but the depth of the grooves is slightly shallower on the BR99 and also the overall width of the rail is slightly wider on the BR99.

I have also checked this with some Evo rail stock I have on hand, which is being used to make Picatinny rails for my crossbows. The Evo rails match the SIG and Yankee Hill, the BR99 is the odd duck out.

It looks like I have two options:

1) Abandon the Yankee Hill Machine riser and get one with a detachable side plate. I'm not that keen on this because the Yankee Hill Machine Riser is very strong, just the right height and looks good on the BR99.

2) Take a very small amount of metal out of the two grooves on the BR99 rail, so that the screws which tighten the riser can pass.

Does anybody else have this issue?

#2 Post by **Blackstuff** » Mon Mar 16, 2015 1:27 pm

Just sounds like bog standard Turkish precision

I've got slide on Magpul MBUS on mine and I've just tried a laser/torch mount that slides on (rather than clipping on) and they fit fine.

I'd just deepen the groves on the gun if I were you

Odd Job · #3 Post by **Odd Job** » Mon Mar 16, 2015 3:43 pm

It's probably the best option. I only need to take off 1mm. If I get a chance I'll X-ray it beforehand just to give it the once-over...

Odd Job · #4 Post by **Odd Job** » Sun Mar 29, 2015 4:28 pm

Well, this is curious, the problem has sort of resolved itself.
I took off the YHM riser and noticed some of the finish has come off the BR99 rail. I didn't think anything of it and went ahead with the X-rays.
I X-rayed it without the riser and then with the riser, and just for giggles inserted the YHM riser screws to see how far they got before being hung up.
Well, I was surprised to see that they went all the way, very little drag on the BR99 riser. There are some very shallow screw impressions across the grooves where the riser engages the rail. I'm not fussed about that at all, plenty metal available in that area.

I can only guess that removing the YHM riser and reinstalling it has taken just that tiny amount of metal off the BR99 rail, allowing the riser holes to now line up with the BR99 rail grooves. It remains a very tight fit though.

I've gone ahead and tightened the riser securely, put loctite 242 on the threads. As of now, the BR99 has a YHM riser with a Burris Fast Fire III reflex dot on it, mounted in a Flat Top adapter. It sits up pretty high now and will be comfortable to shoot, although it looks ugly as hell...

#5 Post by **ovenpaa** » Mon Mar 30, 2015 10:41 am

Ugly as hell... we need a picture!

Odd Job · #6 Post by **Odd Job** » Mon Mar 30, 2015 6:14 pm

Here it is with the protective cover on the Fast Fire III (you can shoot with it on):

The rest of the images are how it would be used when shooting normally, with the protective cover off:

This is taken with the brightest dot setting because the finer dimmer dots don't get picked up by my camera:

#7 Post by **Blackstuff** » Tue Mar 31, 2015 7:13 am

Oo didn't know you could get a protection mount for the III, might have to have a snoop around for one as it definitely needs it

#8 Post by **ovenpaa** » Tue Mar 31, 2015 8:04 am

Nice, that might make a good anti rotation solution for the level 10 forend.

Odd Job · #9 Post by **Odd Job** » Sun May 24, 2015 3:51 pm

I just had a range session with my BR99 now that it has its new riser and Burris Fast Fire III.
I've run into a small problem in that it is shooting about 15 cm low at 20 yards, and I have run out of UP adjustment on my Burris Fast Fire III.
I am really reluctant to change this sight but if I do, I will be looking for another reflex type sight (I absolutely won't have a tube on this shotgun).
At the moment I can think of two options:

1) Get a new red dot reflex sight that has more adjustment range.
2) Change the Yankee Hill Machine riser for something that has a cant to it, or an adjustment where I can raise the rear.

What do you guys think I should do about this?

#10 Post by **ovenpaa** » Sun May 24, 2015 4:09 pm

20 yards and 15cms low means you need a minimum of 27 minutes so up 0,8mm at the back. How much elevation does the Fast Fire have?

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BR99: non-standard rail?

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