Follow Along for my First AR Build

[Metal god]

Great , looking good . So you did nothing different since last time out and now it works ? If so boy would I hate that , I’d me me confused then ever .

[Brian Pfleuger]

Originally Posted by Metal god

Great , looking good . So you did nothing different since last time out and now it works? If so boy would I hate that , I’d me me confused then ever.

That is correct... and I kind of hate it too, but not as much as I hated it when it didn't work.

Who knows? After the last jam with the Hornady ammo, I took the BCG out, basically looked at it said to myself, "WTH? :shrug:", took it apart, cleaned and oiled it (again) put it back together and the gun has run ever since. The BCG was and has been always properly cleaned/lubed every time and I didn't do anything different... so...

But sometimes you just have to shut the hell up and shoot, I guess.

[Scorch]

Sweet. And it shoots good! Gotta love it! Congratulations!

[Shane Tuttle]

Normally speaking, even well discussed Threads don't last past 3 pages...moreless 174 comments....before one is closed.

This one bucks the trend. And, by looking at the end product, it was well worth most every post.

Congratulations, Brian. That AR of yours turned out to be SICK!

[Metal god]

Yeah and Stag and I are only like 170 of those

[stagpanther]

Yeah and Stag and I are only like 170 of those

It's almost like a playing Clue trying to diagnose weapons issue via internet.

[9x19]

Between stag' and Brian using up all the 'what-could-go-wrongs' I'm still waiting for my first big problem build.

The most angst I've had was a .45 ACP bolt/carrier that had so much extractor tension it jammed right out of the box. Removed the extractor and found an unnecessary o-ring under it. Left it our, re-assembled and never had another issue.

[rickyrick]

Stag always kinda takes one for the team lol, I always wait to see what new combinations he tries out.
I appreciate that he posts what goes right and what goes wrong with his different projects.
I’m sure that it has been helpful for many along the way.

[Metal god]

Checking back in , hows it going ?

[stagpanther]

Stag always kinda takes one for the team lol, I always wait to see what new combinations he tries out.
I appreciate that he posts what goes right and what goes wrong with his different projects.
I’m sure that it has been helpful for many along the way.

I'm just blessed that way. LOL. Brian's was technically a tough one to take on for a first-time AR build (I guess a good one for learning from "what could possibly go wrong").

[Brian Pfleuger]

Originally Posted by Metal god

Checking back in , hows it going ?

Sorry guys, don't have much to report, been busy.

Mild curiosity the last time I was out. I have that Sig BDX3Sierra scope on there. I ran some numbers until I figured out what zero would make it 1.9" high at 100 (because that's the range I have solid accuracy for) and entered the numbers in the scope.

I put up a target at 300 yards and my son and I shot multiple two shot "groups" (two just because). My first shots were like 5" high. I thought that was odd. I adjusted the supposed MV in ballistics calculator to a rough estimate I've seen for the barrel length and ammo (Hornady Black 105gr) and figured out what zero would be again for 1.9" high at 100... lower, but still several inches high at 300. So, I just aimed dead on and I was only about 3" low (JBM says should be about 6").

I guess I'll have to break down and do some actual testing instead of wild-ass-guessing

On the plus side (yes, two shot groups, I know), the gun shot great. Between 20 rounds my son and I shot there were not 2 consecutive shots 2" apart at 300... and no jams.

[Metal god]

I guess I'll have to break down and do some actual testing instead of wild-ass-guessing

Yep always have to dope the rifle to the load and scope/reticle . I don't think I've ever had a load , rifle , scope and ballistic calculator ever agree where to aim . they can get you close but I've always had to adjust the scope some to have it dead on . Fun fact it will only be dead on for the ammo you zeroed it to . Change ammo and POI changes . Again you'll still likely be close but it won't be dead on .

Glad to here it's working well , You're likely close to forgetting all the drama that went before . Couple more range trips with the rifle putting them right where you want them and all will be forgiven

[HiBC]

Be sure you have accurately measured and entered the line of sight above the line of bore dimension.
Its a major player.

[Metal god]

Be sure you have accurately measured and entered the line of sight above the line of bore dimension.
Its a major player.

Agreed , used to guess and once I started actually measuring the POI was much closer at multiple distances .

[stagpanther]

Be sure you have accurately measured and entered the line of sight above the line of bore dimension.
Its a major player.

That was my first thought as well--that mount looks like you're pushing at least 1.75 to 2 inches high--does it have any MOA cant built into it? That also can throw your calculations and the ability of the scope depending on the range of MOA the scope has. Your over-all variation in POI elevation doesn't seem out of the ordinary to me in terms of "major malfunction" little changes can make a big difference as the distance stretches. What IS important is whether your scope is tracking accurately or not--I would get a solid velocity chrono on your ammo then run a tracking test after doping your bullet drops per MOA/Mil. Bryan Litz has a good video on how to do that on Youtube someplace.

[Brian Pfleuger]

Originally Posted by HiBC

Be sure you have accurately measured and entered the line of sight above the line of bore dimension.
Its a major player.

It's my first AR but it ain't my first rodeo

2.73", give or take.

Originally Posted by stagpanther

What IS important is whether your scope is tracking accurately... I would get a solid velocity chrono on your ammo...

No chrony. :shrug:
The scope tracked beautifully at 100. I didn't do any fancy box tests or anything but it went where I moved it.

The scope has the ability to fudge it. You tell it your actual zero, estimate the muzzle velocity and then shoot at a longer range (say 275 actual zero and then shoot at 400). You then tell the scope how far off you are and it calculates what MV would result in that trajectory.

[stagpanther]

No chrony. :shrug:
The scope tracked beautifully at 100. I didn't do any fancy box tests or anything but it went where I moved it.

The scope has the ability to fudge it. You tell it your actual zero, estimate the muzzle velocity and then shoot at a longer range (say 275 actual zero and then shoot at 400). You then tell the scope how far off you are and it calculates what MV would result in that trajectory.
__________________
Nobody plans to screw up their lives...
...they just don't plan not to.
-Andy Stanley

Some shooters find chronos useful for estimating velocities.

I had to long onto Sig's site in order to find out more the BDX 4.825.RPGthermonuclearhypersonicautomaticX1PGFR6754.09xpzdq system .
I tend to get a bit leery of techno-jargon that doesn't really mean anything to me.

I assume you used the optional range-finder which as far as I can tell allows you to use, store and generate ballistic solutions? I don't understand how it can a generate velocity solution without first recording multiple range impacts and then "reverse engineer" your cartridge velocities. When I see auto-optic ballistics generating features under $1K--the first thing that pops into my mind is "Uh oh, made in China."

Nearly 3" high off your bore centerline and only 55MOA elevation along with a flat-shooting new cartridge is where I'm guessing somewhere the issue lies in getting your hold-over/under calculations accurately repeatable.

[Scorch]

Wow. Smart scopes. Hmmmm.

Just get it out and shoot it. Quit playing around with high-tech toys. It only takes 10 seconds to tell your smart scope how far the target is that will only be there for 2 seconds. I'm not saying the fancy tech toys aren't useful, but they work best on a range. Paper doesn't move around much while you're fiddling with the knobs. But hey! It's your show!

And once again, this opinion is worth almost as much as you paid for it.

[Brian Pfleuger]

Originally Posted by Scorch

Just get it out and shoot it. Quit playing around with high-tech toys. It only takes 10 seconds to tell your smart scope how far the target is that will only be there for 2 seconds. I'm not saying the fancy tech toys aren't useful, but they work best on a range. Paper doesn't move around much while you're fiddling with the knobs. But hey! It's your show!

The odds are exceedingly high that this gun will never kill anything but paper and, if it does, it will have long since been sighted in properly.

[langenc]

Get whatever you like. That is why I have the adj stock, for length changes from summer t-shirt to deer hunting w/ down jacket and for my stiff/arthritic shoulder. Didnt ever consider a 'fixed' stock.