FTF, Ammo and Magazine comparison, and exploding target!

[gsmopar]

I have a couple threads on this board describing the gun build and several issues that you guys have helped me overcome.  Currently, I'm on a quest to find inexpensive ammo that will actually work in my gun.  I've been experiencing FTE, often times holding the spent round while attempting to load the next into the chamber.  I was mistaken in my last thread when I suspected it was a 7.62 vs 308 issue.  After I looked through my Ammo orders, my last batch of "bad" ammo was 308.  I have 4 metal DPMS magazines and 2 PMAGs all 20 rounds.  I attempted to segregate the magazines to determine if it was a magazine issue, but so far I can only conclude that my gun doesn't like many brands of the cheap stuff.   

 

Details below, along with a video of an exploding target.

 

https://www.facebook.com/photo.php?v=10151705859164426&l=7205561078234421217

 

Prvi Partizan  FMJ-BT, 308, 145grain:  I used both DPMS and PMAG magazines with this ammo.  I experienced 5-10 FTE per 40 rounds.  I attempted to shoot full 20 round magazines, 1/2 loaded 10 rounds, 5, 4, 3, 2, and 1 round tests in both types of magazines.  The bolt locks back on an empty magazine every time.  One of the FTEs occured during a 1-round test.  The round just kind of sat inside the gun.  Other times it was still on the BCG, smashed against the top or opening edge, or wedged into the chamber with the next unfired round.

 

PMC FMJ-BT, 308, 147grain:  Same performance as the Privi

 

Federal XM80C, 7.62, 149grain:  40 rounds through the PMAGs with no issues.

 

Winchester Powerpoint, 308, 180 grain:  20 rounds through the DPMS magazines with no issues.

TraJeTech, 308, 175grain:  40 rounds through the DPMS magazines with no issues.

Hornady ZombieMax, 308, 168grain:  20 rounds through the DPMS magazine with no issues.

Winchester FMJ NATO, 7.62, 147grain:  FTE through the DPMS magazines, but not as often as the Privi or PMC.  I have not tried the PMAGs with this ammo.
 

[MikedaddyH]

Greg why don't you take me and Tom out to your spot in the desert. We can figure it out while dumping a few hundred rounds downrange.

Edited September 27, 2013 by MikedaddyH

[survivalshop]

Number your magazines for reference in testing. In some cases you can use masking tape with the numbers . I use red nail polish , but don't tell my wife .

[Boerboel guy]

I haven't seen your other posts so this may have been addressed already, but I would take a look at your extractor. It may not have enough tension or it may have a messed up claw on it that doesn't properly engage the case.

That and I would check your chamber for burs, scratches, buildup, or just being too tight.

Do any of your spent cases have odd scratches on them?

[gsmopar]

Greg why don't you take me and Tom out to your spot in the desert. We can figure it out while dumping a few hundred rounds downrange.

 

Sounds good to me.  When do you guys want to go?

[gsmopar]

I haven't seen your other posts so this may have been addressed already, but I would take a look at your extractor. It may not have enough tension or it may have a messed up claw on it that doesn't properly engage the case.

That and I would check your chamber for burs, scratches, buildup, or just being too tight.

Do any of your spent cases have odd scratches on them?

 

I don't have any spent ammo pics (I should have thought of that), but here is the extractor and BCG:

 

 

 

 

[MikedaddyH]

Greg, soon we can figure it out.

[washguy]

Hi GsMopar      Could be the it just doesnt like some of the underpowered  junk as in cheap ammo? I wont use cheap privi after having half the primers blow out!  I cant afford to shoot fgmm either....privi in the  white/blue box is junk....privi match in 168 gr is awesome from my gun...moa at least... try that stuff   :)  Wash

[seasprite]

When the last time you cleaned under the extractor and the ejector? Sometimes I get a little brass back in those areas. 

[washguy]

When the last time you cleaned under the extractor and the ejector? Sometimes I get a little brass back in those areas.

Yeppers and the bolt face is nasty too.....solvent city for you wash

[98Z5V]

I think it's the ejector.  It's extracting alright - you're getting rounds out of the chamber, just not out of the rifle.  Hence, the double-feeds.  Either the ejector spring is broken, the ejector itself is cracked/broken (but still retained in the bolt), or the dimensions are off (and the damn thing is tight). 

 

If it's tight, that'll work itself out with time, probably.  If something is broken, it's easy enough to replace.  I've got a jig made up to remove ejectors.  I'm sure Mike has something along those lines, too.  <thumbsup>

 

I'm game for shooting (almost) anything, guys.  I'm hitting the CG Range next weekend, on Sunday (Oct 5th or 6th, whatever Sunday is).

[Robocop1051]

That reminds me. I need to make a jig for my vise. Doing the bolt by hand is a killer!!

[gsmopar]

I pulled everything apart to clean and inspect.  The ejector is firm, but moves freely when pressure is applied.  I did not attempt to remove it from the bolt.  I have a wear mark around the bolt that stops at the extractor (2nd pic).  Is this normal?  Thoughts and opinions?

 

 

 

[washguy]

Mopar    that wear mark is something ive never seen....all of mine are clean of any wear marks....you are on to something I think :)  Wash

[seasprite]

Its hard to tell in the pic but does your ejector have a bur on it  

 

 

 

This pic here makes it look like its got a bur or some peening going on or its just the lighting reflecting off the ejector.

[survivalshop]

Brownells has a nice tool for removing the ejector .

http://www.brownells.com/gunsmith-tools-supplies/rifle-tools/bolt-tools/ejector-tools/ejector-removal-tool-prod23114.aspx?avs|Make_3=AR-15/M4&avs|Manufacturer_1=BROWNELLS

 

The photo's in your post #6 ,looks like components are on the dry side ,as far as lubricant . 

 

I'm curious about the wear mark on the out side face of the bolt carrier .

Edited September 29, 2013 by survivalshop

[98Z5V]

I pulled everything apart to clean and inspect.  The ejector is firm, but moves freely when pressure is applied.  I did not attempt to remove it from the bolt.  I have a wear mark around the bolt that stops at the extractor (2nd pic).  Is this normal?  Thoughts and opinions?

 

 

 

Even if the ejector is bad (can be a couple things wrong with it), it still might move freely in the bolt.  If the ejector spring is broken, and overlapping at the broken ends, it'll still move most of the time.  If the ejector is cracked below the recess for the roll pin, it'll still move - until the broken end binds it up. Honestly, I'd say check it first, no matter what, and eliminate it as a source of the problem.  Remove and inspect. 

 

I'm not sure on your bolt face - it looks fine to me.  If the talk is about the wear on the front of the bolt face, then I've seen that routinely, on different builds of mine and on issued service rifles.  Bolt face wear = no big deal.  If the talk of the wear is about the ring around the inside of the bolt face, that looks like machining to me - it's too uniform.  Too perfect.  I''d think that if it's truly "wear," it would be off to one side or another, not perfectly centered, at the same angle, same depth, etc.

 

Dunno.  I'd pull the ejector first and check it out thoroughly.

[gsmopar]

I ordered an ejector, spring, and retaining pin.  I didn't want to go through the hassle of tearing apart the bolt without having new parts to put back in it.  I'm going to try it once without the $70 Brownells jig (might try to make my own).  I was browsing through several part options on Midway (BCG, bolt, bolt rebuild kits, piece parts, etc...) and noticed this review.  I wonder if they had a bad run?

 

Midway review:

 

Replaced bolt when I bought a Krieger Barrel. The only problem has been with the extractor. Ordered a new extractor spring and that helped. The bolt itself is great, good quality. Just need to pay more attention to the springs.:)

[MikedaddyH]

You can do the assembly with three hands. Just get your spouse to hold the bolt as you put the parts in and squeeze the pin down.

[planeflyer21]

I use an empty case to compress the ejector.

 

With the extractor still installed on your bolt, hook the case into it firmly and compress the ejector. This should allow you to be able and push out the retainer pin on the ejector.  CAREFULLY relax your tension.

 

Or you can buy the $70 tool.

[98Z5V]

^^^  That's what I use the vise for.  Cut off about 1/2" of spent brass (the bottom 1/2").  Use a 1/2" drill bit and channel the skinny side of a 2x4.  You want the 2x4 longer than the bolt, and the channel should be as deep as the distance from UNDER the locking lugs down to the bottom of the bolt.  The bolt should bottom out in the channel, and the lugs should stick out, all the time the bolt is resting in the channel.  Place the bolt in the channel, locate the ejector retaining pin, remove bolt, and drill a 1/4" hole down into the 2x4 to drive the ejector retaining pin into.   Lay this whole crazy mess in the jaws of the vise, stick that cutoff brass onto the boltface, and slowly close the vise.  Pop the pin, and slowly open the vise. 

 

It sounds tougher than it is.  I know pics would help, but I can't find the piece of wood and brass (in a ziplock bag) since I moved this summer.  It's somewhere.  I'll look around today and try to find it.  Again. 

[survivalshop]

That tool also does AR 15's & I removed them for many years with my hands & a pin punch.

 

That tool makes it so easy to remove /install , you will want to disassemble & clean & inspect more often.

[unforgiven]

I use an empty case to compress the ejector.

 

With the extractor still installed on your bolt, hook the case into it firmly and compress the ejector. This should allow you to be able and push out the retainer pin on the ejector.  CAREFULLY relax your tension.

 

Or you can buy the $70 tool.

I haven't tried it on Ripper.But did the same exact thing on the Garand and it worked.

[gsmopar]

The new parts showed up yesterday.  There is a HUGE difference in spring pressure form old to new with the new spring being significantly harder to compress.  Also differences in ejector design and retaining pin length.  Details below:

 

 

 

[survivalshop]

The new spring will help & it appears the Ejector pin is a stronger design . I will have to look at all the 308 bolts I have to see what they look like & that includes the new NIB BCG I just got not too long ago .