new here need a little help.
You are Unregistered, please register to use all of the features of FirearmsTalk.com!    
Firearm & Gun Forum - FireArmsTalk.com > Long Guns > Auto & Semi-Auto Discussion > AR-15 Discussion > new here need a little help.

Reply
 
LinkBack Thread Tools Display Modes
Old 03-16-2015, 01:19 PM   #1
Feedback Score: 0 reviews
 
Join Date: Mar 2015
Posts: 6
Default new here need a little help.

Hello I just finished my ar build everything works great cycles great no issue but I cannot get my sights Zeroed I'm using military issue targets at 25 yards and I just don't have enough adjustment on my sights to get it right. Now I'm using cheaper polymer flip sights but read alot of reviews before going that route and seemed no one had any issues with them so idk if it's the sights or not. My first issue was I ordered a low profile gas block and the sight sat to low I have since then fixed that issue. But still can't get it right I may just go with magpul flips just don't wanna spend the money of it won't fix my problem. Here's my rifle standard bushmaster xm15 with h-bar all magpul accessories and spikes tactical can the flip sights I got from amazon for 20 bucks the quality is pretty good I am happy with the way they look and feel but if they don't zero there useless. I know most people say not to mount a flip sight on the gas block but I'm not dumping mag after mag through it so shouldn't have to worry about melting and yes the gas block is on the same plane as the reciever rail.

srt_dave is offline  
 
Reply With Quote

Join FirearmsTalk.com Today - It's Free!

Are you a firearms enthusiast? Then we hope you will join the community. You will gain access to post, create threads, private message, upload images, join groups and more.

Firearms Talk is owned and operated by fellow firearms enthusiasts. We strive to offer a non-commercial community to learn and share information.

Join FirearmsTalk.com Today! - Click Here


Old 03-16-2015, 02:35 PM   #2
Moderator
FTF_MODERATOR.png
Feedback Score: 0 reviews
 
JonM's Avatar
 
Join Date: Nov 2009
Location: Rochester WI,Rochester WI
Posts: 19,096
Liked 6660 Times on 3544 Posts
Likes Given: 498

Default

you have a couple issues.

cheap knock off sights prolly wont line up on a precision rifle much less a bushmaster the rifle is not the issue.

your putting polymer on a gas block. eventually the heat will melt them even if the knock offs did line up.

if your gas block is not centered on the axis of the bore it will never line up regardless of the sight. if your mounting a sight to a gasblock the gasblock must be square and centered or the front sight will never zero cheap knock off or not. you cannot just pop the gasblock on and put a sight on top and call it done. check my post in the stickies at the top on how to align a gas block. there are several techniques for getting one square.

the military uses a 25 meter zero not 25 yards. even so every click is going to shift poi by .5 at 100 and only .125 at 25. so the more you crank on the sight adjuster at 25 the more drastically off you will be at 100. so you can be spot on at 25 but way off at 100. the 25m military target is not for getting a zero its only a quick way to adjust a previously zeroed rifle to an individual new shooter assigned that rifle.

a new build or new gun should always be zeroed initially at 100.

the proper method is to mechanically zero your sight for windage and elevation. this means it is set in the middle of its movement range so it has the same amount to go up or down or left or right. then you fire at 25 yards/meters. if on paper you note the location from center. back out to 50. if your not on paper something is wrong with the gun setup and should be vhecked oug by a gunsmith. no rifle should be outside a 18"x18" target. fire again. if your on paper move to 100. if your not on paper adjust sights until you are.

this is where your previous notation on the 25 target plays a role. if your 25 group was up and left you adjust down and right 4 clicks each and refire. if your not on paper adjust 2 clicks refire repeat until on paper. note location of hits. repeat at 100 until your on paper. once on paper you can zeto for 100.

once you have zeroed for 100 then you can move to 25 and fine tune for your 25 yard/meter zero
__________________
"Gun control: The theory that a woman found dead in an alley, raped and strangled with her panty hose, is somehow morally superior to a woman explaining to police how her attacker got that fatal bullet wound." L. Neil Smith

The problem with being stupid is you cannot simply decide to stop doing dumb things...

"I crapped my pants to avoid the draft!!" -Ted Nugent

Last edited by JonM; 03-16-2015 at 02:40 PM.
JonM is offline  
 
Reply With Quote
Old 03-16-2015, 03:07 PM   #3
Feedback Score: 0 reviews
 
Join Date: Mar 2015
Posts: 6
Default

Thanks for the info the way I centered the gas block I got a nice flat edge flipped the rifle over and pretty much pressed down on the rifle making sure that everything was night and tight against the flat edge then while holding pressure on it I had my wife lock it down to make sure it wouldn't move. As far as the gas block that's seems fine. When sighting the rifle I'm a bit higher then where I wanna be but every shot was at least on paper. But on the paper aiming about center mass I was a little over head shot so maybe the sights are just not cutting it. Which is a shame cuz for being cheaper sights they are pretty good quality and fit well but if they don't work doesn't matter how nice or good looking they are. I noticed while adjusting the front sight I would have to turn it all the way up to get close to center mass but adjustment is maxed out so no go with these and I'm not sure if I add a rail to my magpul moe grip if it will be level with the receiver. I would hate to even think this myself but if the front sight needs to move up just a bit I have seen small risers but I don't know if that will be to much I'd prefer to fix the problem correctly if possible. As far as grouping left and right that's not an issue I'm on the center of paper just can't get the up and down adjustment needed. For a cheapy ebay gasblock for 15 bucks I'm super happy with it it sealed great no leaks fit nicely and snug was real easy to install and telling by the ejection pattern I'm pretty sure everything's working correctly there actually never had an ejection pattern so tight together when trying to sight the rifle I had a nice little pile of brass did even have to search for an randomly flung brass lol.

Last edited by srt_dave; 03-16-2015 at 03:58 PM.
srt_dave is offline  
 
Reply With Quote
Old 03-16-2015, 06:22 PM   #4
Moderator
FTF_MODERATOR.png
Feedback Score: 0 reviews
 
JonM's Avatar
 
Join Date: Nov 2009
Location: Rochester WI,Rochester WI
Posts: 19,096
Liked 6660 Times on 3544 Posts
Likes Given: 498

Default

i can tell you that your moe handguards are not designed to mount a sight. they are designed to work with a front sightbase gasblock like these



these fsb gasblocks cannot be mounted to a rifle barrel unless holes are cut in the barrel gor mounting. this operation requires special jigs a a drill press and special bits. its a job that is one of the two things on a ar15 that really isnt diy for most folks

most likely your gasblock is not an upper receiver height gasblock. this is almost a rule with picatinny gas blocks. you need an upper reciever hieght gas block like these

http://www.midwestindustriesinc.com/index.cfm?fuseaction=category.display&category_ID= 252

measure the diameter of the barrel at the gas port it should be .750 before ordering.

you will need a metal front sight as you cannot mount a polymer to a gasblock and keep it from melting.
__________________
"Gun control: The theory that a woman found dead in an alley, raped and strangled with her panty hose, is somehow morally superior to a woman explaining to police how her attacker got that fatal bullet wound." L. Neil Smith

The problem with being stupid is you cannot simply decide to stop doing dumb things...

"I crapped my pants to avoid the draft!!" -Ted Nugent

Last edited by JonM; 03-16-2015 at 06:25 PM.
JonM is offline  
 
Reply With Quote
Old 03-16-2015, 06:44 PM   #5
Feedback Score: 0 reviews
 
Join Date: Mar 2015
Posts: 6
Default

This is what my rifle started out as. My gas block I have now is rail height I made that mistake already and got a low profile one when I ordered this one I made sure to ask alot of questions before buying. Even after I installed it I used alot level to make Sure and it is indeed rail height. I may have to figure out another solution or change to a troy h&k style sight and I'll coat it in od green that's why I didn't go with metal I didn't want to have to coat them but I can do it in an hour so no big deal I do like the hk style front sight picture so maybe I'll go that route when money permits.



srt_dave is offline  
 
Reply With Quote
Old 03-16-2015, 09:54 PM   #6
FTF_SUPPORTER.png
Feedback Score: 0 reviews
 
Mercator's Avatar
 
Join Date: Sep 2013
Posts: 8,026
Liked 3796 Times on 2600 Posts
Likes Given: 1899

Default

Plastic BUS folders make sense only if you normally use optics. Otherwise HK peepholes and a fixed iron front would be the best.
Mercator is offline  
 
Reply With Quote
Old 03-16-2015, 10:10 PM   #7
Feedback Score: 0 reviews
 
Join Date: Mar 2015
Posts: 6
Default

Darn I like the look of the flip sights I'm gonna do some more tinkering to see if I can come up with a solution to this problem I don't wanna use the standard post sight that's why Isi took it off lol although it worked flawlessly. Now after searching for hours on Google for random pics everyone says that polymer sights will melt but I cannot find one piece of evidence to prove this does anyone have a pic of a melted sight? As the old saying goes pics or it didn't happen. If a polymer sight would melt don't ya think a polymer lower receiver would melt as well?

Last edited by srt_dave; 03-17-2015 at 03:18 PM.
srt_dave is offline  
 
Reply With Quote
Old 03-17-2015, 06:13 PM   #8
Feedback Score: 0 reviews
 
fsted2a's Avatar
 
Join Date: Apr 2008
Posts: 1,272
Liked 260 Times on 207 Posts
Likes Given: 399

Default

Quote:
Originally Posted by srt_dave View Post
Darn I like the look of the flip sights I'm gonna do some more tinkering to see if I can come up with a solution to this problem I don't wanna use the standard post sight that's why Isi took it off lol although it worked flawlessly. Now after searching for hours on Google for random pics everyone says that polymer sights will melt but I cannot find one piece of evidence to prove this does anyone have a pic of a melted sight? As the old saying goes pics or it didn't happen. If a polymer sight would melt don't ya think a polymer lower receiver would melt as well?
Go to Magpul's webpage. They tell you not to mount poly sights on gas block for that reason. The poly front sight is supposed to be mounted on railed same plane handguard (which they don't sell). Suggest you get a metal front sight and call it a day. I don't have any problems with flip sights. Also, I think there are a few threads on this forum with melted poly receivers.
__________________
"Democracy is two wolves and one sheep voting on what to have for dinner.
Liberty is the well-armed lamb contesting the vote." - Benjamin Franklin
fsted2a is offline  
 
Reply With Quote
Old 03-17-2015, 06:38 PM   #9
FTF_SUPPORTER.png
Feedback Score: 0 reviews
 
Mercator's Avatar
 
Join Date: Sep 2013
Posts: 8,026
Liked 3796 Times on 2600 Posts
Likes Given: 1899

Default

Quote:
Originally Posted by srt_dave View Post
Darn I like the look of the flip sights I'm gonna do some more tinkering to see if I can come up with a solution to this problem I don't wanna use the standard post sight that's why Isi took it off lol although it worked flawlessly. Now after searching for hours on Google for random pics everyone says that polymer sights will melt but I cannot find one piece of evidence to prove this does anyone have a pic of a melted sight? As the old saying goes pics or it didn't happen. If a polymer sight would melt don't ya think a polymer lower receiver would melt as well?
All I can say, never seen it or heard from anyone that his BUS melted on a semi-auto rifle. On the other hand, you get more options with fixed sights. I have used a fiber optic front post and even a battery powered green dot front post, that was a real deal.
Mercator is offline  
 
Reply With Quote
Old 03-17-2015, 06:42 PM   #10
Feedback Score: 0 reviews
 
Join Date: Mar 2015
Posts: 6
Default

I'd never buy a poly receiver to begin with that to me is just asking for trouble now I understand they stay not to mount it on a rail gas block but if the rail block is same plane as the rail on the receiver it should not make any kind of difference whether it's mounted on a handguard or railed gas block. I'd hate to change my hand guard cuz I like the look of the magpul one. Unless my issue is that the sights I have are just to cheap. I know the guy that owns a local gun shop and smith so I'll ask to borrow a set of magpul sights and try and zero the rifle again and if it zeros I'll just buy the sights off him. I don't see an issue why mounting on the gas block would he a problem unless your dumping mags or full auto I like to make my shots count so over heating a gas block won't be a problem. I've seen poly receivers crack and break but never one melt.
srt_dave is offline  
 
Reply With Quote
Reply

Thread Tools
Display Modes




Newest Threads