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9/22/2017 12:11:25 AM
Posted: 9/10/2003 5:23:46 PM EDT
[Last Edit: 9/10/2003 5:47:08 PM EDT by James_Gang]
This is the result of shooting a new Bushmaster M-4 type A-2(14.5" barrel with intergral mini y brake) this weekend at the local police range.

Prior to this day, the rifle had a total of 79 rounds. It has never suffered a malfunction.

It is really a large grouping considering I was sighting the weapon in at 100 yards off a sand bag with the stock iron sights, and made more than a few sight adjustments. The bullseye is 8", about the size of ones head. I'm very pleased with the results.

My first two groups of 5 rounds were high, as you can see from the picture(notice the sub MOA horizontal spread). After a couple of clicks down I was right in the bullseye. I then cranked a few clicks of windage in either direction(small group to the left and right), and settled for something in the middle as one can see from the expanded groups in the bullseye. After 50 rounds the groups started spreading slightly(might have very well have been me, and my 42 year old eyeballs).

My last 10 round string was shot with the ghost ring, which explains the larger group and the flyers off to the right. It appears when switching to the ghost ring I need a couple of clicks of left windage, vs. the smaller apeture setting to be in the center of the target.

It was shot with Q-3131A ammo. I'm amazed that this stock rifle/ammo combination appears to be easily capable of producing groups in the sub-MOA range with a good scope and a good rest.

The stock trigger can be described as good.



Semper fi
Link Posted: 9/10/2003 6:56:17 PM EDT
[Last Edit: 9/10/2003 7:09:12 PM EDT by FL-AR15]
I went to the my local range today, and re-sighted my BM M4A2. I sighted mine in at 50 yards so that it would also zero in at 200 yards. I didn't have much time so I shot 30 rd groups after sighting in. At 75 yards it was almost 4" higher center of aim. Shooting prone at 100 yards it was almost 7" above center of aim. Which worked out great because I was able to place the target just above the front sight. Leaving me with a clear picture of the target. I have shot well over 3500 rds through my BM M4 A2. My groupings have steadily increased. Maybe I am just becoming a better rifleman, or maybe my rifle is. Shooting bench at 50 yards my group of 30 rds was just under 4", and at 75 yrds it was just under 4-1/2", but shooting prone at 100 yards it was 6-1/2" tall and 4" wide. Please keep in mind that I was shooting with iron sights. I was once again very pleased with the results. BM's AR15s are by far one of the worlds best shooting weapons available for the price. Edit to add... I have had only one malfunction with my BM M4 A2, and it was my stupid fault for not following good cleaning habits. Yes, I learned from that, and I am very religious about cleaning my AR.
Link Posted: 9/10/2003 7:09:31 PM EDT
[Last Edit: 9/10/2003 7:28:08 PM EDT by James_Gang]
Originally Posted By FL-AR15: I went to the my local range today, and re-sighted my BM M4A2. I sighted mine in at 50 yards so that it would also zero in at 200 yards. I didn't have much time so I shot 30 rd groups after sighting in. At 75 yards it was almost 4" higher center of aim. Shooting prone at 100 yards it was almost 7" above center of aim. Which worked out great because I was able to place the target just above the front sight. Leaving me with a clear picture of the target. I have shot well over 3500 rds through my BM M4 A2. My groupings have steadily increased. Maybe I am just becoming a better rifleman, or maybe my rifle is. Shooting bench at 50 yards my group of 30 rds was just under 4", and at 75 yrds it was just under 4-1/2", but shooting prone at 100 yards it was 6-1/2" tall and 4" wide. Please keep in mind that I was shooting with iron sights. I was once again very pleased with the results. BM's AR15s are by far one of the worlds best shooting weapons available for the price.
View Quote
----- Yeah that sounds alot like my experience FL. You see my first two groups are about 4-6" high at 100 yards. This is after sighting in at 50 yards(IBZ). However for a 200 meter IBZ zero one should only be printing a maximum of 2" inches above point of aim at 100 yards. I had to drop my sights back to 1 click up elevation to print in the right spot(1.5-2" above P.O.A. at 100 yds). Like Chuck says, that's why it's always important to verify ones 50 yard zero at longer ranges, preferably at 200 meters which is actually the correct zero. Like I said you can do this roughly at 100 yds, just make sure your P.O.I. is 1.5-2" above P.O.A. At 4" high at 100 yards, your zero is more like 300 meters instead of 200 meters, which isn't a problem as long as one remembers to place the target above the front sight post, and doesn't expect pin point accuracy out to 300 meters. At 7" high at 100 yards, your zero is more like 375 meters, which equals almost 10" high at 220 meters. On a normal size dog that's the knees. If you don't have a 200 meter range to verify your 50 yard zero and you want the real IBZ, go back to the 100 yard range and adjust your sights to print point of impact at 1.5-2" inches about point of aim. This will put you right in the bullseye at 200 meters(true IBZ)at point of aim and allow you to be within 2" of your point of aim all the way out to 220 meters(which is the whole reason for the IBZ). Otherwise your range scale beyond 220 meters on your rear sight wont work. The trouble with only using a 50 yard sight in zero without verifying the elevation sight setting at the zero range(200 meters), is it is easy to make a small point of impact elevation error at closer ranges that equals a big mistake at longer, or at ones actual zero range. Confused yet? That's why zeroing ones weapon at short ranges is really just to get one on the target at the actual zero range. Therefore, if you desire point of impact, point of aim accuracy, you must also zero the weapon at its actual zero range. For the IBZ this is 200 meters.
Link Posted: 9/10/2003 7:25:18 PM EDT
So let me make sure I am understanding this right. At 100 yards, I would want my POA to be 1.5" above my POI in order to get a 200 yard zero? I could have sworn that a 50 yard zero would produce a 200 yard zero as well. However, the range I am a member of only has a 100 yard rifle range. I am going to switch my membership to another range in December that has a 300 yard range and is working on a 1000 yard range. So I won't be able to really push the envolope until then.
Link Posted: 9/10/2003 7:33:36 PM EDT
[Last Edit: 9/10/2003 7:41:36 PM EDT by James_Gang]
Originally Posted By FL-AR15: So let me make sure I am understanding this right. At 100 yards, I would want my POA to be 1.5" above my POI in order to get a 200 yard zero? I could have sworn that a 50 yard zero would produce a 200 yard zero as well. However, the range I am a member of only has a 100 yard rifle range. I am going to switch my membership to another range in December that has a 300 yard range and is working on a 1000 yard range. So I won't be able to really push the envolope until then.
View Quote
----- I had to correct my post, as this is getting confusing. Remember we are talking meters not yards for the zero of the IBZ. The actual zero we want at 8/3 -2 is 200 meters. That means we want the round to strike at point of aim at 200 meters. From out of the barrel to 220 meters the bullets trajectory will not be more than 2" above or below your point of aim. It just so happens that the bullet roughly intersects the sight plane at 50 yards. So one can sight in at 50 yards and get a rough zero. Notice I said rough. That's why you're so high at 100 yards. You should be close to 1.5-2" high at 100 yards with a true IBZ 200 meter zero. So to answer your question, you should go back to the range and make sure you're printing 1.5-2" high at 100 yards. Then when you switch ranges, zero your weapon at 200 meters, point of aim, point of impact. Then you will be properly zeroed for the IBZ. And give them tin cans, etc... hell. No need to hold low. Your range wheel will also work for 300 meters and beyond. Point being is 50 yards is really just to get you on the paper. If you want point of aim, point of impact accuracy at the proper zero range and you want your range wheel to operate properly, you should verify your sight settings at this range. For the IBZ that is 200 meters. Like I said, it's possible to do it at 100 yards, but you must determine the bullets trajectory at 100 yards with a 200 meter zero. For the IBZ this is 1.5-2" high at 100 yards.
Link Posted: 9/10/2003 7:39:46 PM EDT
James, you wouldn't happen to be talking about the range in Gastonia would you?
Link Posted: 9/10/2003 7:42:38 PM EDT
Originally Posted By -Absolut-: James, you wouldn't happen to be talking about the range in Gastonia would you?
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------ Yeah man. Only decent public range around here. I wish they had more than 100 yards.
Link Posted: 9/10/2003 10:04:21 PM EDT
wow, it [b]is[/b] a small world afterall....we shoot there a good bit, but i'm at school now in Clemson....maybe we've ran across each other before? i wish the range was open more b/c you're right, there's not really anything else around. Are they still not letting people shoot under 100yards? i saw the new rule last time i was there, they said they had some problems with rounds skipping over the backstop
Link Posted: 9/11/2003 3:52:56 AM EDT
Didn't look like they were letting any public types shoot at shorter range than 100 yards. Most guys looked content to do the 100 yard thing anyway. They had the air national guard down there doing some fam fire the day before I was there. Old guy said they were shooting at 25 meters. I got some decent stripper clips out of the deal. He also said they were shooting the .50 caliber bolt action rifle. That's the first time I've been down there. I prefer to shoot out in the country. Decent range though. I had a good time. Good luck at Clemson.
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