TA31RCO on a midlength

**reccerecon** · 07-11-11, 16:29

I can't seem to find the info I need so maybe someone here can square me away. I just got a TA31RCO for M4's in a trade and I'm wondering how the BDC will work on a 16" midlength upper? My experience with ACOG's is limited to TA01NSN's on 14.5" M4's. I know if it isn't a good match then I can just record the impacts and adjust for there. Would it just be better to try and get a different model for the uppers I use and if so what do you recommend? All I have now are 16" midlenghts. I've tried the search on multiple site but couldn't find what I needed. Thanks for the help.

**ICANHITHIMMAN** · 07-11-11, 16:51

Middlength or carbine length should have no effect. Its the 1 1/2" more barrel you have that is going to create more speed than the 14.5" barrel on your M4 this making you BDC off but just a bit. I would say its so small you should not worry about it. But if you cant stop thinking on it you can give it to me.

**reccerecon** · 07-11-11, 17:00

That's what I was thinking. I thought it would be a good idea to know for sure before zeroing it. Thanks again for the help.

**BooneGA** · 07-11-11, 20:07

The BDC stadia are simply a guide. Unless you actually shoot the rifle at those ranges there really is no way to be sure. Different rifles, barrel length, ammunition, and enviromental factors (such as elevation) play heavily into the flightpath of the bullet.

If you are going to rely on them, I would reccomend taking the rifle out and verifying the accuracy of the stadia even on a 14.5 inch military M4 shooting M855.

Rick

**R0N** · 07-12-11, 04:36

The BDC is good enough for government work. It is based on standard MV, at sea level and 50 degrees.

**Failure2Stop** · 07-12-11, 11:32

In my experience, 75 and 77 grain loads from 16" barrels shoot very close to the stadia built for M855 from 14.5 barrels if zeroed at 300 meters.

**reccerecon** · 07-12-11, 21:33

That answers my next question, I was planing on trying M855 first but that will save me some ammo. I am going to test dfferent bullet weights so I'll have an idea what to expect.