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9/22/2017 12:11:25 AM
Posted: 10/20/2003 7:53:45 PM EDT
Thank you for looking as always

I just noticed on Bushmaster's site that they recommend a .040 higher front site post when deploying an ARMS #40 BUIS. This is the first I've heard of this-is it true?

Here is the specific link Bushy ARMS #40 link

Thank you in advance for your assistance!
Link Posted: 10/20/2003 7:58:28 PM EDT
[Last Edit: 10/20/2003 7:58:50 PM EDT by glock23c]
If I remember right, I just backed my front sight out about a half turn and it zero'd just fine. I am using a 16" Bushie with the ARMS 40A2.
Link Posted: 10/20/2003 8:15:09 PM EDT
I need a taller front sight post with mine. I haven't done it yet and I had to almost completly unscrew the post to get it to zero. It is so high I'm waiting for it to just fall out. You might try it first and see. Who knows, you may get lucky.
Link Posted: 10/20/2003 8:46:48 PM EDT
A Colt A3 flattop sight plane is 0.040" higher than the A2 sight plane, they actually have a different front sight casting. When Bushy made their flattops they decided to use a A2 front sight casting, and lower their carry handle. If you are going to use a ARMS #40 then yes you will need the taller front sight post.
Link Posted: 10/20/2003 9:04:55 PM EDT
Originally Posted By Omega_556: A Colt A3 flattop sight plane is 0.040" higher than the A2 sight plane, they actually have a different front sight casting. When Bushy made their flattops they decided to use a A2 front sight casting, and lower their carry handle. If you are going to use a ARMS #40 then yes you will need the taller front sight post.
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Ahhh, thanks for the info [:)] Since my M4 carbine [i]is[/i] a Colt with the higher front sight plane does that mean I don't need the higher post? Sorry that I didn't specify that in the beginning. I shop frequently at Bushmaster.com due to their close proximity to my home, but my three ARs are Colts. Thank you Glock23c and 455SD for your expertise as well.
Link Posted: 10/21/2003 5:07:53 AM EDT
Originally Posted By Omega_556: ...When Bushy made their flattops they decided to use a A2 front sight casting, and lower their carry handle. If you are going to use a ARMS #40 then yes you will need the taller front sight post...
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I have a 100% Bushmaster manufactured flattop upper with an ARMS #40. It did not require a taller sight post. Bud
Link Posted: 10/21/2003 9:15:45 AM EDT
Originally Posted By Omega_556: A Colt A3 flattop sight plane is 0.040" higher than the A2 sight plane, they actually have a different front sight casting. When Bushy made their flattops they decided to use a A2 front sight casting, and lower their carry handle. If you are going to use a ARMS #40 then yes you will need the taller front sight post.
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This is correct, however, when I set-up my #40 [booze] on my BM M4, I purchased the taller front sight in anticipation of using it. Like "Bud", I too, did not need it.
Link Posted: 10/21/2003 10:24:51 AM EDT
Bud & Notack, You were lucky I guess, or maybe it is a timeframe issue. Maybe they used the colt front sight casting in the past? I don't know what to say as I'm no great AR technical master but that info I posted earlier was strait from Bushmaster, as I asked before I ordered my 16" M4gery upper when I saw the not about the ARMS #40 sight on thier website. I also ordered it in anticipation and definitely needed it after trying to zero without it. My front sight post base was over the detent to get it to zero. My front sight post is just about level with the ears that protect the front sight post. However it's a moot point, as I'm going to get the GG&G flip up front sight.
Link Posted: 10/21/2003 3:41:22 PM EDT
If Bushmaster knew what they were talking about, they would mention that any mil spec fold down rear sight may need a higher front sight post if used with their front sight housing that is lower than mil spec used on gov't M4's. Good shootin, Jack
Link Posted: 10/21/2003 3:53:25 PM EDT
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