weak primer strike?

[JDePietro]

Ladies and Gentlemen of the EBR counsel,

I present my case to you, I do so without pictures and don't ask for any. No one shall see Ivy before she is done, and as of now she is not.
I started my project way back in April and for the most part it has been smooth sailing. This past week I purchased a set of YHM BUIS's. This allowed me to begin the barrel break in and finally have a chance to shoot my new creation.

Methodically shooting and patching made for not so great groups but I was able to at least get the windage set perfect. This leads me to question 1.

Lowering the front site will bring the following shots up? I had thought this to be correct but I was corrected by someone else and with my other problems soon to be addressed I can't seem to make any sense of it. I'm about 98% sure I'm right but I figured it can't hurt to ask just to make sure.

My second question and the title of this thread requires back story.
The barrel I have is a SS, .223 chambered, 1-9 twist, monster made by DPMS. The ammo I used was a mix bag of American Eagle 5.56 Tactical XM193 and Ultramax .223, both were 55gr fmj.
Before I get the lecture about using 5.56 in a .223 chamber I was assured that I would not have an issue because DPMS uses a similar chamber as the Wylde chambers. The problem I experienced was not concurrant with the problems associated in using 5.56 in a 223 chamber.
My issue is actually the opposite of a punctured primer.
out of the 50 rounds I fired I had 8 rounds that did not. When I felt it was safe I unloaded the round only to find a barely dented primer. Out of the 8 misfires I reloaded the ammo and got 6 of them to fire.

So what caused a weak primer hit?

With the problem at hand I decided to cut my session short and address the problem. I took it home cleaned up and dissasembled the trigger group parts. This is where I discovered that the trigger pins have two slots in them. I installed the pins without noticing or giving thought to this so I re-installed the pins with the slots closest to the right side.

Was this the problem? Will what I did fix it?

The rifle was made from brand spankin new parts and it was well oiled and cleaned prior to test firing. I see no problem with the firing pin and everything else works fine.

Could it have been the ammo?

Thank you in advance for all of the assistance.

[Warners Surplus]

It could be one of several things.

1. improperly installed hammer spring
2. weak hammer spring
3. crud or foreign matter in the bolt that is limiting fireing pin travel. did you check the 5.56 brass to make sure you had no punctured or blown primers? pieces of primer anvil or carbon from blown primers can limit firing pin travel.
4. real hard primer cups


As for the trigger and hammer pins, the grooves in the pins work with the hammer spring and detent to stop the pins from walking. The center groove in the hammer pin engages a detent in the hammer to stop it from walking. The hammer spring engages the outside groove in the trigger pin to stop it from walking. It really doesn't make a difference which way you install them because the hammer spring will sit in the groove on either side of the trigger pin and the other groove is center. I have always installed them with the outside groove to the left but that just me.

Rich W.

[Legion_Prime]

Lowering the front site will bring the following shots up? I had thought this to be correct but I was corrected by someone else . . .

"someone else" is either a moron or was not thinking straight. Everything else left the same, lowering the front sight post will require you to raise the muzzle end of the rifle or lower the buttstock to achieve the same sight picture thereby raising the point of impact. You were correct.
As for the light primer strikes, the only thing I can add to Warners response above is to make sure that the firing pin is not oiled excessively. THis can gum it up in cold weather but can also attract more fouling than normal and gum up the firing pin.

[JDePietro]

No punctures, that was my first guess.

When I cleaned the rifle last night it was not very dirty. There were no pieces of brass or more than usual fowling*.
(That I have seen on AR's before.*)

I installed the springs as I was instructed to and cross referenced those instructions with diagrams on http://www.ar15.com/forums/topic.html?b=3&f=4&t=226782.

If I had installed it improperly I don't think it would have fired any of the rounds.

The weak hammer spring theory is one I have, but it seems so unlikely.

How much oil is too much? I don't oil the firing pin all on its lonesome but I am sure it receives some when I oil the bolt and bolt carrier.

Just an FYI... I use Eezox, Royal Purple, and small amounts of Lucas Oil to lube and clean my guns.

Keep the thoughts coming...

http://eezox.com/gun-care.html
http://royalpurple.com/assembly-lube-o.html
http://www.lucasoil.com/products/

[rflynn]

What ammo was it that you had the problem with?
Was the bolt completely closed when you pulled the trigger?

[JDePietro]

A thought came to mind last night, and I have not had the chance to replicate it.

Is it possible to insert the cotter pin incorrectly?
And by that I mean get the pin in without having the firing pin in the correct location?

You must understand that I am a moron and anything is possible, so please firing away with some of the most off the wall ideas, I am open to all so that in the future if it is something completely avoidable I can do just that.

[Lycanthrope]

I don't think you pinned the firing pin in wrong. It's possible, but very improbable.

Lucas Oil is way too thick in cold temps. I'd keep it off of the BCG.

Is the BCG chromed?

Going back to what rflynn mentioned and the fact that this may be a new gun.....it's possible it's just tight and not going fully into battery. Anytime an AR chambers at speed from the magazine it will dimple the primer due to the floating firing pin. Is this the dimple you were talkig about....or was it deeper?

Were the misfires more likely to come from the first round in the mag?

Also, is the Ultramax .223 "remanufactured"/reloads?

Lycancouplequestionsthrope

[Hawk]

If you put the carter pin in wrong, it won't fire at all. I suggest 2 things (and they are cheap), replace hammer spring and replace the firing pin. It's possible to put the hammer spring in wrong, but you stated you're sure it's correct, so try replacing the spring. A field repair kit is a good idea to have anyways.

link: http://www.cheaperthandirt.com/ARR076-7.html

[JDePietro]

I do not apply the lucas to the bolt group.
The lucas is used on the bottom of the bolt carrier were it contacts the hammer and also on the charging handle where it contacts the loop for the but stock.

I use a little tiny bit of RP on the bolt face where it contacts the chamber gear/crown(?)

The lucas is more for the rails on my 1911 and even so its a very small amount applied.

I spray down the bolt carrier group with Eezox. I do not oil the bolt seprately with anything because I know the eezox gets to it. Eezox tends to dry and make sort of a dry film the little bit of RP oil makes sure it stays wet where it needs it.

The entire rifle at one point or another has been coated in eezox to protect the finish but all of that soaks in and the excess is whiped off per the instructions on the site.

The rifle does dimple round when I load the rounds but I should expect it would do more when the trigger is involved.

The rounds that jammed where in various stages in the magazine no particular order.

Yes the Ultramx is the reloaded stuff.

There is no doubt in my mind that a few of the rounds were duds. When I reloaded a few and attempted to use them the firing pin did make the dent larger and certainly large enough that the round should have gone off.

Perhaps the ammo is more to blame than what I give it credit?

As far as I know the bolt carrier and group are phosphate coated, I do not believe they are cromed.