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Posted: 12/20/2009 10:16:20 PM EDT
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Gents,
I'm planning on getting one around spring time...I noticed there are 2 versions an M4 and A4. How much of a difference between the reticles? I was wanting an ACOG that would work on my 20", 16", and 14.5" ARs. That being said, is the M4 specifically calibrated for true 14.5" barrel balistics? If so, how does that affect the majority of shooters mounting this on 16" barrels? Please offer some info as I don't want to drop $1,300.00 if it's not compatible with all my ARs. If it's not compatible - I may just go with a Nightforce 2.5-10x24 NXS. Thanks! Sakic #19 
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A4 is specifically calibrated for the 20" barrel (using M855 I think). M4 is calibrated for the 14.5" barrel.
While the BDC will obviously not be dead on given a different barrel length, the same will occur with different ammo. Check out the tacked ACOG BDC thread and you should gain a better understanding of what might work and what might not. |
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Quoted:
A4 is specifically calibrated for the 20" barrel (using M855 I think). M4 is calibrated for the 14.5" barrel. While the BDC will obviously not be dead on given a different barrel length, the same will occur with different ammo. Check out the tacked ACOG BDC thread and you should gain a better understanding of what might work and what might not. The BDC for the 20" barrels were calculated using M193 55gr ammunition. The BDC for 14.5" models were calculated using M855 62gr ammunition. Yes, any BDC will be "close," but that also depends on your definition of "close." Close enough to hit a man-sized target out to 400yds? Yes. Close enough to hit a bullseye consistently? No - for that, you'll need the BDC to match near-perfectly. |
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Quoted:
Quoted:
A4 is specifically calibrated for the 20" barrel (using M855 I think). M4 is calibrated for the 14.5" barrel. While the BDC will obviously not be dead on given a different barrel length, the same will occur with different ammo. Check out the tacked ACOG BDC thread and you should gain a better understanding of what might work and what might not. The BDC for the 20" barrels were calculated using M193 55gr ammunition. The BDC for 14.5" models were calculated using M855 62gr ammunition. Yes, any BDC will be "close," but that also depends on your definition of "close." Close enough to hit a man-sized target out to 400yds? Yes. Close enough to hit a bullseye consistently? No - for that, you'll need the BDC to match near-perfectly. I believe that the BDC for the TA31-RCO models (both A4 and M4) were calculated using 62g M855. If you want pinpoint accuracy then go with the Nightforce or similar scope. I use my ACOG's primarily for military knockdown silhouettes, where minute-of-man sized target is good enough. |
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Quoted:
Quoted:
A4 is specifically calibrated for the 20" barrel (using M855 I think). M4 is calibrated for the 14.5" barrel. While the BDC will obviously not be dead on given a different barrel length, the same will occur with different ammo. Check out the tacked ACOG BDC thread and you should gain a better understanding of what might work and what might not. The BDC for the 20" barrels were calculated using M193 55gr ammunition. The BDC for 14.5" models were calculated using M855 62gr ammunition. Yes, any BDC will be "close," but that also depends on your definition of "close." Close enough to hit a man-sized target out to 400yds? Yes. Close enough to hit a bullseye consistently? No - for that, you'll need the BDC to match near-perfectly. The ACOG is not a target scope and was not designed to be one, so dot shooting should not be expected. Leupold makes nice scopes that are designed to shoot "X" scores. ACOGs are designed to hit men at ranges that would be hard using iron sights. The ACOG is designed to improve the chances of hits. Nowhere in the design specs was target shooting at a Camp Perry type range considered. In 2007 here at Lejeune as I have relayed several times this was tested live on the range at Stone Bay. 10 shooters were gathered along with 5 M16A4 service rifles topped with RCOA4s and 5 M4s topped with RCOM4s. M855 ball all of the same lot was used for the test. A zero was done at 100m on both sets of weapons/sights. A course of fire from 200, 300 & 500m was done and the results recorded. At that point the optics were swapped from M4s to the A4s and vise versa. The shooters had the same weapons but different optics and the zero was redone and the course of fire was repeated. When the smoke cleared and the targets were pulled and results were examined guess what? The overall scores were the same. Therefore you decide. If it makes you feel better to have M4 on your scope go for it. |
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