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My son and I each recently built our own AR15s which we took to the range for the first time yesterday. Both rifles used DPMS stripped lowers and DPMS lower receiver parts kits, which were all purchased at the same time.

On my rifle, after about 20 or 30 rounds, I noticed that both the trigger pin and the hammer pin had backed out of the left side of the receiver a short distance - maybe 1/16". I was able to push both back in by hand, but they both moved a little bit again by round 40. In fact, the trigger pin had backed all the way out of the right side of the receiver so that it was only supported on the left. I've probably shot 500-600 rounds or more through my Bushmaster, and I've never seen this phenomenon before.

2 questions...

1. is that a common problem with home built ARs?

2. what is the remedy?

remove the pins, flip them around, and re-insert them. While you have the pins out inspect the fire control group you should be able to see the following:
1: There is a small spring inside the hammer (viewable from the hole the pin goes in) that should catch the cut in the middle of the pin "locking" it into place.
2: The disconnector should catch the middle of the pin also "locking" it into place.

Sometimes the cut in the pin's middle is not 100% in the middle. If it walks out some distance but never catches you can usually flip the pin around and it will walk until it catches. If the problem persists you can always invest in some anti-walk pins. A friend of mine had this issue on his Bushmaster and we had to flip the pins around and it locked up just fine.

I'll try that. Thanks. My son actually assembled my lower while I was out running an errand. He was working on his when I left. When I got back, he had also done mine. He mentioned yesterday that the pins had a detente built into them, but he also said that he was sure he had installed them correctly. Well, I'll take your suggestion and see what happens. Thanks again for the advice.

I'm wondering if a drop of clear fingernail polish on the ends of the pins wouldn't also be a good idea. I notice that the DPMS lower is a much looser fit to the upper than on my Bushmaster. On the DPMS, I can push the takedown pin out with my finger. It doesn't move, it just pushes out very easily. By contrast, my Bushmaster takedown pin has to be driven out with a nylon dowel and a small mallet.

The Annoyed Man wrote: On the DPMS, I can push the takedown pin out with my finger. It doesn't move, it just pushes out very easily. By contrast, my Bushmaster takedown pin has to be driven out with a nylon dowel and a small mallet.

The Bushmaster sounds too tight or the pin is just really dry. Since the rifle is designed to be broken down without tools, in the field, the most that you should need is a round of ammo to push the pin through. If it's a competiton rifle for precison shotting then the tighter the better, otherwise a little loose is OK.

ScubaSigGuy wrote:

The Annoyed Man wrote: On the DPMS, I can push the takedown pin out with my finger. It doesn't move, it just pushes out very easily. By contrast, my Bushmaster takedown pin has to be driven out with a nylon dowel and a small mallet.

The Bushmaster sounds too tight or the pin is just really dry. Since the rifle is designed to be broken down without tools, in the field, the most that you should need is a round of ammo to push the pin through. If it's a competiton rifle for precison shotting then the tighter the better, otherwise a little loose is OK.

This Bushmaster is a precision varmint rifle, so it doesn't bother me that it is tight.

G.A. Heath wrote:remove the pins, flip them around, and re-insert them. While you have the pins out inspect the fire control group you should be able to see the following:
1: There is a small spring inside the hammer (viewable from the hole the pin goes in) that should catch the cut in the middle of the pin "locking" it into place.
2: The disconnector should catch the middle of the pin also "locking" it into place.

Sometimes the cut in the pin's middle is not 100% in the middle. If it walks out some distance but never catches you can usually flip the pin around and it will walk until it catches. If the problem persists you can always invest in some anti-walk pins. A friend of mine had this issue on his Bushmaster and we had to flip the pins around and it locked up just fine.

G.A. Heath, Here's what we found out....

Chalk this one up to inexperience, these being our first AR builds, but we had installed the hammer springs backwards in both rifles. Therefore, the straight ends of the spring were sitting at a downwards angle relative to the trigger pin, instead of horizontal within the receiver. Since they were at an angle, there was not enough tension on the spring with the hammer forward to keep the straight end of the spring inside its detente. As soon as we reversed the hammer springs and buttoned the rifles back up, the trigger and hammer pins were properly locked in place with an audible "click!" It's one of those stupid but important little details I'll never forget, no matter how many times I strip or build an AR from now on.



I'm just glad that nothing broke because of our ignorance. Thanks for the help, guys.

I'm glad to hear you got it resolved. Now if my custom barrel comes in and my gas system parts ever make their way to my mailbox my newest build will be ready for night hog hunting.

G.A. Heath wrote:I'm glad to hear you got it resolved. Now if my custom barrel comes in and my gas system parts ever make their way to my mailbox my newest build will be ready for night hog hunting.

I hear that. I would like to get a new upper in either .450 Bushmaster or .458 SOCOM for hog hunting. BTW, does anybody make an ambidextrous safety for AR15s? I'm left handed, and I can cope with the magazine release and bolt release buttons being on the "wrong" side of the receiver, but the safety on the wrong side is just a big pain in the elbow.

There are ambi-safeties for the AR15 family of rifles. Brownells and Midway USA usually have a DPMS manufactured unit, right now it may be out of stock. I think I would take a 6.8 Rem SPC hog hunting before investing in the .450 and the .458 uppers. We have only encountered one hog with a 6.8 and fired only one shot using a Hornady 110 hollow point. The pig was very dead. I have since planned a build for a night vision hunting rig.

The Annoyed Man wrote:... As soon as we reversed the hammer springs and buttoned the rifles back up, the trigger and hammer pins were properly locked in place with an audible "click!" It's one of those stupid but important little details I'll never forget, no matter how many times I strip or build an AR from now on.



I'm just glad that nothing broke because of our ignorance. Thanks for the help, guys.

The great news is the hammer pin is usually first to fail when you assemble things wrong. This pin only cost about $1.20, so it is a cheap repair. One thing you may want to consider is buying one of the AR emergency parts kits. You can have a parts guy at a gun show put one together for you for around $15, with all the spare parts and springs you need for field repair.

G.A. Heath wrote:There are ambi-safeties for the AR15 family of rifles. Brownells and Midway USA usually have a DPMS manufactured unit, right now it may be out of stock. I think I would take a 6.8 Rem SPC hog hunting before investing in the .450 and the .458 uppers. We have only encountered one hog with a 6.8 and fired only one shot using a Hornady 110 hollow point. The pig was very dead. I have since planned a build for a night vision hunting rig.

I'm curious. Why not go with a .308 instead of the 6.8 mm? Wouldn't that make the rifle even more versatile?

The Annoyed Man wrote:

G.A. Heath wrote:I'm glad to hear you got it resolved. Now if my custom barrel comes in and my gas system parts ever make their way to my mailbox my newest build will be ready for night hog hunting.

I hear that. I would like to get a new upper in either .450 Bushmaster or .458 SOCOM for hog hunting. BTW, does anybody make an ambidextrous safety for AR15s? I'm left handed, and I can cope with the magazine release and bolt release buttons being on the "wrong" side of the receiver, but the safety on the wrong side is just a big pain in the elbow.

I am currently gathering parts to build a low-light (night) AR hog gun.

I have settled on the .458 SOCOM, I like having the great range of bullet weights (and construction) to choose from.

The hogs we have around here will weigh anywhere from 90lbs. to well over 300lbs.

As you know with hogs, you don’t always to get “pick your angles” after the first shot.

Living in the Pineywoods…shots are normally less than 100 yds. (usually under 50), with all this in mind, the SOCOM makes the most sense (for me).

Bullet weights run from a diminutive 85 grs. (no that’s not a typo), up to a 600gr. Solid.



Here are some pics for comparison:




Most folks stick with 300gr.-400gr. Bullet for hogs and Deer, but a 250gr. will easily get the job done.


It goes without saying that “bullet placement” is key to taking game cleanly/quickly, and doubtless…lighter, less powerful rounds can be successfully employed, but big hogs…at odd angles, require a cartridge that will “deliver the goods”. It is not unusual to need 20”-24” inches of penetration to reach the vitals when you have other than broadside or frontal shots.

The option of course (and a perfectly good one), is to carefully choose a single target and be satisfied with that. Unfortunately, we often have so many hogs doing so much land damage, that taking “one an outing” would be like fixing the “dripping” faucet while the tub is running over.



One caveat: Unless you reload…be prepared to pay about $60.00 a box (shipped to you) for ammo. If you have deep pockets, I guess a person could afford to “plink” and have fun with this set up, otherwise…sight it in and shoot wisely.

Personally, $3.00 a pig is something I’d do all day (if they would stand still). Destructive devils!

Pics of your EEEEvil black rifle....or it didn't happen

The Annoyed Man wrote:

G.A. Heath wrote:There are ambi-safeties for the AR15 family of rifles. Brownells and Midway USA usually have a DPMS manufactured unit, right now it may be out of stock. I think I would take a 6.8 Rem SPC hog hunting before investing in the .450 and the .458 uppers. We have only encountered one hog with a 6.8 and fired only one shot using a Hornady 110 hollow point. The pig was very dead. I have since planned a build for a night vision hunting rig.

I'm curious. Why not go with a .308 instead of the 6.8 mm? Wouldn't that make the rifle even more versatile?

I went with the 6.8 because it has about half the recoil of the 308 while delivering around 70% of the energy. The faster time back on target afforded by the lower recoil and my magazines capacity permit more kills should we encounter large sounders. Here in West Texas we are more interested in hog extermination than we are anything else so when we run into a large sounder we open up on then and try to cleanly drop as many as possible. Anything less will annoy the farmer and can result in you being told to hunt somewhere else. Now don't misunderstand me, we are not just shooting into the group hoping to hit them, we are carefully picking shots but we have had around 200 hogs run in front of us at one time. You can tell when a hog gets into a peanut field as they will pick a row, follow it, and completely eat every thing planted in it. The 6.8 lends itself well as good hog cartridge, and I am told it makes an excellent deer cartridge.

Aaaahhh. I wasn't aware that the recoil from the .308 in an AR was that significant of a problem, but then I'm used to shooting 175 gr Match Kings out of a heavy barreled bolt rifle in .308 (which weighs about the same as my AR varmint rifle in .223/5.56). I assumed that a .308 AR, weighing about the same as my bolt rifle, and having the gas recoil system, would actually have milder perceived recoil. I guess I've got a lot to think through.

Where I'm hunting (Jack County), long range is perhaps less of an issue than it is in West Texas. That's why I was thinking of the .450 Bushmaster or .458 SOCOM for hogs. The ballistics out past 150 yards are still good, but you have a heavy bullet which will buck brush mo' bettah.

Two other questions... With the 6.8 SPC, is bullet placement on a hog as critical as it is with .223; and how is the commercial availability of ammunition?