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View Full Version : Short gas block on DPMS AR15. Decent iron sights?



John in WI
06-17-2023, 06:44 PM
About 2 years ago, I picked up a DPMS AR15. I got it used, but it looked to have been used very little. It came without sights. I had hoped to put on some basic iron sights, and only then realized that the DPMS has a gas block that's much shorter than the rail on the receiver. I looked around, and web company called "Green Blob" claimed they had a set that would work. They seemed to be built well enough. Unfortunately today, there just is not enough elevation to get it on target at 50 yards. It's still like a foot high!

I cranked the rear sight as far as it would go. Then, I was adjusting the front sight. Up, up, up, and doink--the damn retaining pin popped out (lost in the grass). Now I have a front sight with about 2mm of wiggle in it.

I was hoping not to run optics on it. I just wanted a very basic, very rugged rifle. I had no idea there were tall and short front gas blocks.

Can anyone recommend a set of irons that would work with a short gas block?

I was thinking, if I did put on a red dot, it would be cool to get some offset sights for it as a backup. But if I can't find regular iron sights, I'm sure I have no chance of finding offsets.
Thanks for any info. I've never owned an AR, I sort of wish I had researched this more. I'm not out too much, but still.

Rapier
06-18-2023, 11:14 AM
Multiple problems, multiple answers. You can get different versions of off set open sights. How you mount them has much to do with the gas block and the gas tube length, forearm length and type. A picture of your AR would have been helpful.

Take mag out and unlad the gun.

With few tools you can change the gas block out for a larger multi rail type block, easiest to mount sights on, if the gas block is out in front of the forearm, you can change the gas block fairly easily.
Remove the bolt and operating handle, then separate the upper receiver from the lower receiver, then remove the fore-end barrel cover from the upper receiver, remove the flash suppressor if any, from the muzzle, then remove the gas block, it should be held in place with one screw or two screws, then tap the gas block off the barrel trunnion and the gas tube with come off with it. There is a roll pin through the gas block, when the gas block is loose from the barrel, the tube will pull out of the upper in one assembly. A padded vice can be used to hold the gas block, in order to remove the roll pin with a small punch and light weight hammer. It should Not be necessary to remove the barrel nut or barrel from the upper receiver. When replacing the block and re-installing the gas tube, make sure you buy the correct trunnion size gas block, most AR-15 barrel trunion are .750 However some trumions are smaller and some are larger do make very sure your barrel trunnion and the ordered replacement block are for the same size. Then when replacing the gas tube pin turn the rolll pin so it blocks gas flow to the outside of the gas tube, roll pins have a slot which should not be directly over the barrel's gas port. put the tube and block together off of the barrel and upper, then slide the tube/block assembly onto the barrel, aligning the barrel gas port hole, use ye holecand screw marks to algn, just finger snug one screw, then put the operating rod and BCGS back into the upper and push the carrier forward with a thumb to ensure easy and proper fit. With the bolt forward and lugs closed, tighten both screws on the gas block. Then pull the carrier back about 80%, push the operating rod forward then while holding the upper at 60 degrees, release the carrier, it should fall, bolt should close and lock by gravity. Remount the forearm cover, muzzle flash suppressor and install the new rail mounted front and rear sights to be level at the top, offsets are available for rail mounts ftom Amazon or Brownells, Brownells has at least three different trunnion sized gas blocks. Without reloading you will not really need an adjustable gas block.

Gtek
06-18-2023, 12:36 PM
What about a short Weaver rail riser?