Looking for AR help

[agustuscain]

I hope to get some advice from someone who knows how to or has done this before. I have a Bushmaster XM15-E25 with a carry handle upper. I want to switch to a Flat top upper and I am not sure on what brand to purchase and while doing some research I have found people who have had problems with getting the gun zeroed or not being able to match up the rear sight and front sight. This particular Bush has the gas block welded on so I don't even know IF it can be removed. I've also found information about feed ramps which I know nothing about.

If someone can help me with what to buy I would appreciate it.
Thanks.

 

[itsa pain]

should not the front sight be pinned on? unless someone took a welding class on it. if the front sight tower is marked F standard rear sight will matchup. the front site and rear have so much vertical adjustments it don't matter anyway. any namebrand upper will work well a 1x8 twist I like the best. do not fall for unless you buy the best upper all others are junk

 

[briansmithwins]

With the welded gas it's basically not worth it to try to swap uppers. I'd sell what you have and turn the cash into a flat top upper and barrel.

BSW

 

[ID-shooting]

I agree, being welded will make it difficult. There should be someone local wanting to go the other direction and will swap. The other is sell and fork over a little cash or trade at the store and spend a little more. Last resort, new upper should only be a few hundred and have both.

 

[agustuscain]

Ok thanks guys for your response and advice.

 

[jakk280rem]

Are you sure your gas block is welded on and not your muzzle device? Sounds like you have a post ban or ban state rifle. Swapping to an A4 upper should be a simple matter. Your gas block and or front sight post and your muzzle device shouldn't need to be removed to swap to another upper.

 

[DougW]

It is possible to change the upper with a front sight or flash hider welded on. You have to be able to remove the gas tube from the front sight, which will require you to have the proper tools and a GOOD vice. I have done it on a couple of rifles, but if you screw up getting the gas tube out (which will probably be difficult if the rifle has been fired a lot) you will end up with a bigger mess than you have now.

You could build a new upper with the reciever and barrel set up you want. But, everytime I did this, I end up building out a lower, and presto, another rifle. They do have a tendency to breed like rabbits, at least at my house.

 

[MattShlock]

I don't get the consternation or bad advice about not being able to just put an upper in the configuration the OP wants on his current lower. Nor the gunsmithing difficulties -- if someone is moderately handy and has invested in the proper tools it is easy. Oh, and, get an adjustable rear sight if "zeroing" it in after taking a removeable carry-handle/sight off is your concern.

This'n might look familiar...

 

[ID-shooting]

They do not have to be removed and could be assembled accordingly, buuuuuut, he would then have a "standard" front sight base on a flat upper. To do it properly he should change out the front sight to a "flat" one of the correct height. If it is welded on, it becomes a challenge.

 

[1911Jeeper]

Unless you really want to buy the necessary AR-15 tools, simply buy any complete AR-15 upper receiver assembly that meets your needs, and fits your budget. Then put it on your lower, and shoot it. If you have any front sight issues, you can buy a taller sight post, or shorten a sight post to the needed size.

Your existing upper can be kept, or it can be sold to reduce the final cost of the new upper receiver assembly.

All the tacticool, secret ninja fighter, mumbo-jumbo keywords, can be ignored.

AR-15's are almost 99.99% plug and play, any reasonable quality upper receiver assembly you buy will function correctly and sight in correctly on your Bushmaster lower.


.

 

[mljdeckard]

Yeah, I match #9. I am the kind of guy who wil tinker with these kinds of things, but just as often I will wind up with a bag of spare parts and wind up just buying the new upper anyway. It's certainly not a bad thing to just have a spare upper.

 

[cfullgraf]

They do have a tendency to breed like rabbits, at least at my house.

Not just your house.

("Only two, only two." from Bill Cosby's Noah's Ark routine)

 

[jakk280rem]

So it sounds like he has some options. If he can get the gas tube out then he's good to go on a direct swap, but will be limited as to his elevation adjustments on his front sight. So he then can buy a taller front sight post, or a rear buis designed to work with a non f marked fsp.

if he can get his gas tube out he could shave his gas block and use a free float that utilizes the stock barrel nut. that would allow a much wider selection of sights.

 

[hentown]

I don't see the point of going flat top, unless he wants to use optics. I just don't use iron sights at all, on my ARs. Brownell's has Aero stripped uppers for $75 right now. I just bought one, but don't even know when I'll do anything with it.

 

[jakk280rem]

In the thread he started at arfcom, he expressed a desire to run some sort of optic. he probably doesn't have the coin for a new complete upper and a new optic. plus on this current climate, it may be difficult to find a complete upper with a bcg. Unfortunately the bottom of the are market has dropped, or he could have sold the upper or complete rifle for enough to buy a new one set up how he wants today.