Firing pin drag

[3jaw]

I have now put about 100 rounds through my built from the ground up Les Baer 5" 1911 and I have been getting slight primer drag marks. I cannot figure out why it is happening.

Here are the stats:
Link length: .278
16 Lb Recoil Spring
23 Lb Mainspring
EGW Firing pin stop with a small radius
Wilson Extra Power firing pin spring
Wilson Bullet Proof firing pin
Kart NM Barrel
WWB ammo

Even though I haven't set up any indicators to measure when the barrel starts to unlock, I have used a pair of calipers and a close eye to see that it just starts to unlock at about .100" to .105" of slide travel.

The only real problem that I see is that the primer strikes are a bit high, but the gun has never offered to misfire and the .278 link is the fits just fine with no "riding the link" problems (I think it is either a tolerance stack problem or the firing pin hole is mislocated because I am getting about .048" front lug engagement depth). It shoots hard, seems to hold tight groups (I haven't installed sights yet.) and has been very reliable so far. I have kept the firing pin hole spotless with no crud buildup so I know it isn't the firing pin getting in a bind.

Am I getting my drawers in a wad over nothing or is it something that needs to be addressed?

Any ideas??? :butthead:

Thanks,
Greg

[wichaka]

Post some pics of the fired cases in question..........then we'll see if your drawers need to be wadded or ironed out.

[scooter]

Post some pics of the fired cases in question..........then we'll see if your drawers need to be wadded or ironed out.
Now thats just grosshttp://forum.m1911.org/images/icons/icon8.gif

[wichaka]

Gross???????? :confused:

He was the one who was worried if he needed to get his drawers in a wad or not...........if they do, so be it........we'll fix the gun.

If not, we'll unwad.........or dewad them and iron them smooth again. :D

[3jaw]

Here is a picture.

I could solve the drawers problem by wearing a thong!! :scared:

http://img.photobucket.com/albums/0703/ggordon/primer_drag.jpg

Thanks in advance,

Greg

[Herb Clark]

Looks as if was fired in a Glock!

[wichaka]

That's not bad, I've seen a lot worse.

I would say the barrel isn't quite fitted right, or the link may be a bit short.

..........and I just saw your mention of the .048" lug engagement, I'm not sure what it should be as I'm not home to look it up.........but someone correct me if I'm wrong...........it should be in .055" and above area.

[1911Tuner]

Firing pin length to spec, or a little too long? Full lug engagement is .050 inch. Is the Kart an Easy-Fit barrel...or a full, hard-fit NM? Your link may be a little short for the aggregate vertical dimensions/stacks between slide and frame, and trying to link the barrel down a little too early. Try a .281 link, or elongate the bottom of the hole .003 inch. May work...may not. If you use the .281 link, elongate the TOP of the hole enough to get the slidestop pin back on the lower lug.

[3jaw]

The barrel is a hard fit NM. I will check the firing pin length tonight. I guess it is time to fire up the milling machine and make a .281 link. Would 4142 steel be a suitable material for a link?

Thanks,
Greg

[1911Tuner]

The barrel is a hard fit NM. I will check the firing pin length tonight. I guess it is time to fire up the milling machine and make a .281 link. Would 4142 steel be a suitable material for a link?

Thanks,
Greg

The firing pin strike too high suggests that the barrel isn't moving high enough in the slide. Possibly due to the slide lugs hitting the slots between barrel lugs and stopping it. The .048 lug engagement on the front lug means that the rear is likely engaging to full depth because of the barrel's tilt into vertical lockup, but that's not a sure sign. The tadpole mark on the primer strike says it's high...which means that the barrel isn't engaging to full depth at the rear...or at the first lug. Removing a few thousandths of material in the barrel lug slots will move the barrel higher in the slide, but will reduce the tight vertical lock. If the concave radius at the rear of the barrel feet is within spec, the barrel will still be in full lockup when it fires...as long as
you don't have to take more than about .003 inch or so from the slots...but the gun will be more likely to throw the first round out of the group vertically
because of the different dynamics of going to battery on the hand-cycled first round.

4140 or 4142 should be okay. Heat-treat to about 45 Rc. Specs call for 1075 or 1080 hardened to 45-47 Rc. I've made'em out of 1018 (case-hardened with Kasenit) and had'em last for thousands of rounds. Try elongating the hole at the bottom of the .278 link before you go to all that trouble just to see if it'll work. The old armorers used to do that to fine-tune the links. Max should be held to .003 inch. beyond that, and it's time to go to the next longer link. Marvel makes links in .003 increments.

My bet is that you'll find that the firing pin is either long out of spec...or right on the max allowable...and the link is a little too short, and it's trying to link the barrel down before the firing pin has rebounded. Elongate the link and try it. That'll probably squash the bug. If not...shorten the pin by .003 inch and reshape the tip.

After opening up the link, be sure to run another timing check to make sure the barrel drops in time to get the lugs clear of the slide.

[3jaw]

Well, I have just discovered that I royally screwed up!!! After remeasuring the rear lug engagement, I found out that I don't have .048. I have only .041! What is the actual spec? Is it .050 or .055?

I measured the firing pin and it is actually .024 too short! It measures 2.266 and the spec is 2.296 +0.000, -0.006.

It is sounding like I need a new barrel!!! :mad:

Greg

[1911Tuner]

Well, I have just discovered that I royally screwed up!!! After remeasuring the rear lug engagement, I found out that I don't have .048. I have only .041! What is the actual spec? Is it .050 or .055?

I measured the firing pin and it is actually .024 too short! It measures 2.266 and the spec is 2.296 +0.000, -0.006.

It is sounding like I need a new barrel!!! :mad:

Greg

Nah. You don't need a new barrel. Go ahead and try elongating the hole in the link to see if that'll give you the linkdown delay you need.

The lug spec is .050 +/- .002 inch, so you're a little off the peg for vertical. I just got through with a Kart barrel in a Norinco. Final depth is .048 inch with .051 lugs. Adjusted percentage is 97-ish. 90 and over is good, especially with equal horizontal engagement.
If you've got 82% at the first lug, and the second is hitting...you've still got a stronger lockup than most factory guns.

The off-center strike isn't as critical as the tadpole tail. It may rob you of a little accuracy because of less consistent ignition...but you'd need a solid rest to see the difference.