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Old 06-13-2018, 07:47 PM
JaxMike01 JaxMike01 is offline
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I topped my MP 15 lower off with this.
CBC industries 24 inch Bull barrel upper.
Makes for one long AR.
I’ve only had it to the range once but after sighting in the scope...
Not bad for the first outing at 100 yards.


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Old 06-15-2018, 09:56 PM
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How big is the red dot in the center of your target?
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Old 06-16-2018, 12:06 AM
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Nice shooting!
Dont you just love it when a plan comes together?
Jim
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Old 06-16-2018, 12:08 AM
Racer X Racer X is offline
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Why such a long barrel? The powder stops accelerating the bullet at about 20" for .223/5.56 rounds. If you have iron sights, the longer sight base would help accuracy, but that's not the case here.

Not critical, just asking.

Who makes that free floating lightweight handguard? I REALLY like it.

Last edited by Racer X; 06-16-2018 at 01:03 PM.
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Old 06-16-2018, 06:46 PM
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Why such a long barrel? The powder stops accelerating the bullet at about 20" for .223/5.56 rounds.
I used to believe the same thing, but have learned more. Yes, the powder is done burning at about 18"-22", but that doesn't mean the pressure just disappears. It might not be building, but it's still pushing. The extra 4" will give you a higher velocity without increasing the chamber pressure. This is a good thing when looking for maximum accuracy at longer distances. Out to 200 yards it's only a marginal difference. However, when you get out to 300-500 yards it makes a dramatic difference.
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Old 06-16-2018, 07:30 PM
bamashooter bamashooter is offline
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Nice weapon and all but I'm curious with what you have there (upper), why you didn't mate it to a fixed stock?
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Old 06-16-2018, 09:23 PM
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Quote:
Originally Posted by Rastoff View Post
I used to believe the same thing, but have learned more. Yes, the powder is done burning at about 18"-22", but that doesn't mean the pressure just disappears. It might not be building, but it's still pushing. The extra 4" will give you a higher velocity without increasing the chamber pressure. This is a good thing when looking for maximum accuracy at longer distances. Out to 200 yards it's only a marginal difference. However, when you get out to 300-500 yards it makes a dramatic difference.
^^^ Wut he said.

I had a Colt with a 24" barrel (I installed it aftermarket) and 4-12x variable scope. It made a great gun for prairie dog shooting.
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Old 06-17-2018, 01:33 AM
Racer X Racer X is offline
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Good to know. Thanks for the info.
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Old 06-22-2018, 02:14 PM
wylie won wylie won is offline
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Quote:
Originally Posted by bamashooter View Post
Nice weapon and all but I'm curious with what you have there (upper), why you didn't mate it to a fixed stock?
Agreed! I put a 20" barrel with a rifle length gas system on one of my AR's. I installed a Luth AR MBA 1 (fixed stock) on it. I LOVE the stability.
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Old 06-22-2018, 02:18 PM
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Quote:
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I used to believe the same thing, but have learned more. Yes, the powder is done burning at about 18"-22", but that doesn't mean the pressure just disappears. It might not be building, but it's still pushing. The extra 4" will give you a higher velocity without increasing the chamber pressure. This is a good thing when looking for maximum accuracy at longer distances. Out to 200 yards it's only a marginal difference. However, when you get out to 300-500 yards it makes a dramatic difference.
I have a Savage 12FV in 223 with a 26" barrel. I get crazy velocities out of that rifle. It is probably the most accurate rifle I own. I have zero issues hitting steel at 400 and 500 yards.
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Old 06-26-2018, 10:47 PM
JaxMike01 JaxMike01 is offline
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How big is the red dot in the center of your target?


The red dot is 1.5 inch. I’m still trying to figure out what ammo it likes. Seems to do better with 75gr.


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Old 06-26-2018, 10:50 PM
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Nice weapon and all but I'm curious with what you have there (upper), why you didn't mate it to a fixed stock?


I got the upper complete and just mated it to my MP 15 lower to take it to the range. I’m in the process of building a lower for it now. I am considering a fixed stock though.


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Old 06-26-2018, 10:52 PM
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Quote:
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^^^ Wut he said.



I had a Colt with a 24" barrel (I installed it aftermarket) and 4-12x variable scope. It made a great gun for prairie dog shooting.


I’m actually hoping to take it prairie dog hunting. I’ll need a better scope, I just had the center point lying around.


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Old 07-11-2018, 02:17 PM
JaxMike01 JaxMike01 is offline
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Finished product (for now) I’m still working on the best ammo for it. With a 1:8 twist it seems to like 75gr. I’m getting things together to start reloading so hopefully I can load some precision ammo. After some trial and error I’m sure.


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Old 07-11-2018, 10:13 PM
Racer X Racer X is offline
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Who makes that free floating lightweight hand guard? I REALLY like it.
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Old 07-11-2018, 11:14 PM
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Quote:
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Who makes that free floating lightweight hand guard? I REALLY like it.
AR-15 Rail - 15" CBC Arms Keymod AR-15 Handguard / Rail – CBC INDUSTRIES
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Old 07-14-2018, 04:36 PM
MistWolf MistWolf is offline
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...The extra 4" will give you a higher velocity...
How much extra velocity?
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Old 07-15-2018, 12:15 AM
hdwhit hdwhit is offline
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JaxMike01, you should be very happy. Looks like a quality component. Congratulations.
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Old 07-15-2018, 12:26 AM
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How much extra velocity?
223 Remington/ 5.56mm NATO barrel length and velocity: 26 inches to 6 inches – rifleshooter.com
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Old 07-15-2018, 03:15 AM
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Out of four different loads, the difference in velocity between a 24 inch barrel and a 20 inch barrel was 100 fps or less. One load showed a 200 fps difference, but has less velocity than another load with the same weight bullet.

The juice ain't with the squeeze.
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Old 07-16-2018, 01:14 AM
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The red dot is 1.5 inch.
Thanks for that info. With that I can measure the groups very precisely. I have done that and here are the results:




Now, I'm not trying to rain on your parade, but I measured both of these as 5 shot groups. Yes, I went out on a limb and did that because it's uncommon for someone to shoot a three shot group and then a two shot group. Further, you're trying to find the best load so, evaluating the whole group gives you the best data.

Further still, if you did shoot three shot groups, increase them to five shot groups. Five shot groups give you a better understanding of how the ammo is performing.

Regardless of all that, these are still pretty good groups and better than average. This new upper is working and when you land on the right load it will be under 1/2MOA I'm sure.
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Old 07-17-2018, 12:08 PM
JaxMike01 JaxMike01 is offline
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Thanks Rastoff, I really appreciate your info. These were indeed 5 shot groups. I haven’t had much of a chance to take it back to the range but it does seem to like a heavier projectile. I’ve used some 55 gr. and the groups open up quite a bit. These groups were with Hornady Black 75 gr.


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