My friend purchased a Colt 6721 just after the ban and it has been his primary AR for the last couple of months.  He currently has 620rds through it and ran into a problem with the carrier.  We were breaking down our rifles for cleaning after a day of shooting and he couldn't get the firing pin retaining pin out of the carrier.  After a while we were able to push it out, but noticed that it was bent and twisted.  Taking a closer look at the carrier and firing pin, we noted that the back end of the firing pin retaining collar was showing signs of heavy wear and the edge of the ramp on the bottom of the carrier was actually rolling inward.

Now I know that the wear on the firing pin and carrier is caused by the hammer.  But is this much wear common for 620rds?  I have a preban Colt 6601 that has about the same amount of rounds through it and it doesn't show nearly as much wear (see pics).  The only difference is the lower I run my 6601 upper with has a JP SS FCG with speed hammer.  My friends 6721 has the stock trigger.

What I can't figure out is what is causing the retaining pin damage.  I can't even imagine that the firing pin is hitting the retaining pin hard enough to bend it.

My preban 6601 carrier is on the left and my friends 6721 carrier is on the right.

Don’t you know Colt can do no wrong; they are perfect and make the best of everything so your friend must be stupid as are you for posting such scandalous drivel. I bet you’re lying and that isn’t a real Colt bolt, because nothing colt makes ever fails




In all seriousness, it looks like either the upper or bolt is out of spec. There are plenty of Colt whores here so they will be better qualified to explain what the problem could be

it's scraping on something.

Quoted: Don’t you know Colt can do no wrong; they are perfect and make the best of everything so your friend must be stupid as are you for posting such scandalous drivel. I bet you’re lying and that isn’t a real Colt bolt, because nothing colt makes ever fails

VB,

Are you having a bad day or were you just born angry?  If there is anyone posting drivel, it's you.  Your comments here and at the bottom of this LMT thread here are not productive and are your opinions.  Which were not asked for and are not appreciated.

Quoted: Quoted: I hate to expose my own stupidity, but what does "MRP" stand for? thank you Richard Over priced waste of money.

I know it's a bad carrier design but would like to see if others are experiencing the same issues.  And FYI not all Colt carriers come this way.  I have a three year old 6922 M4 upper that came with a fully shrouded firing pin carrier.

Edited to add: your final comments were not posted when I started this reply:

Quoted: In all seriousness, it looks like either the upper or bolt is out of spec. There are plenty of Colt whores here so they will be better qualified to explain what the problem could be

I had a DPMS carrier and the same thing happened. The little shelf on the hammer would catch the firing pin and bent the retaining pin. I switched to a smooth cornered hammer and a Colt bolt/carrier and the problem stopped. I never knew Colt made carriers like that. I have used  only their M16 carriers and the firing pin area is shrouded.

Quoted: I had a DPMS carrier and the same thing happened. The little shelf on the hammer would catch the firing pin and bent the retaining pin. I switched to a smooth cornered hammer and a Colt bolt/carrier and the problem stopped. I never knew Colt made carriers like that. I have used  only their M16 carriers and the firing pin area is shrouded.

+1 on the shrouded firing pin area.

Found the following information in Zediker "the competitive AR15":

Firing Pins:
"The large collar pins (M16) should only be used in carrier that has a shrouded pin area. Damage will result from using large collar in an open carrier"

Is your friend using an AR-15 or a M16 firing pin?

New hammer or bolt carrier (RRA) may solve the problem.

Did you contact Colt or SAW? I would like to know what they think about it.

Walli

Something is definately rubbing on the carrier the wrong way, that's why it is getting chewed up.  Did he buy that Colt new or used?  The reason I ask is maybe there is something made by another company in there, that does'nt belong.  I had a problem with a used Colt Gov't model 1911 that I bought.  It kept jamming and the slide stop kept catching on the slide.  I took it to Colt and they took it apart to find a non-Colt recoil spring, guide and some kind of recoil buffer in it.  They fixed it for me while I waited and did'nt charge me a cent.

Had a similar problem with the PERFECT COLT PRODUCT.  There was a small burr in inside that gouged up in the same area. I took it off with a small round diamond file. Although I own many Colts their quality is not superior with exception to the bolt heads. Some of the crapiest looking uppers and lowers in my safe are colt. But I do not whine as they are intended to be a tool just like a hammer etc.

Quoted: Had a similar problem with the PERFECT COLT PRODUCT.  There was a small burr in inside that gouged up in the same area. I took it off with a small round diamond file. Although I own many Colts their quality is not superior with exception to the bolt heads. Some of the crapiest looking uppers and lowers in my safe are colt. But I do not whine as they are intended to be a tool just like a hammer etc.

Well your reply was a wealth of useless information.  It sounds like your whining to me?

I bought a (blocked receiver) "pre-ban" Colt HBAR before the ban sunsetted that had been a safe queen. After I put 200 rounds through it, it had the exact same wear marks.  Same thing with the firing pin too.  I wanted to inquire about it here, but have no camera and figured no one would understand a text description.  

The hammer is wearing that spot on the carrier, and I think the notch in the hammer is banging up the firing pin.  The pin came stock with the rifle and the rifle had no mods or parts replaced.  I guess Colt put the incorrect firing pin in it at the factoryI put a RRA "enhanced" carrier in it from Eagle Arms and continued to use the Colt MPC bolt and have had no wear patterns or other problems since.

yup, my MT6601 did the same thing. between the cut hammer and the cut carrier my firing pin was all chewed up.

I replaced the cut carrier/hammer with RRA's carrier and DPMS non-cut (large hole) hammer and life is good.

as for the firing pin retaining pin. it seems that your cut hammer caught your firing ping "as designed" (to prevent burst malfunction) and pulled the firing pin into the retaining pin and bent it. replace the retaining pin and  your good to go.

I can't be sure from that picture, but sure looks like the carrier on the right has a full auto firing pin, while the one on the left is semiauto.  Is that just my perception, or does anyone else see that?  I have heard of full auto parts showing up in NIB Colt's rifles over the years, but never seen it myself.

I took another look, I am sure that is a full auto firing pin, am surprised it would function like that, never tried it myself though.  Am sure Colt's will make it right, if you call them and tell them what happened.  

I have just compared my two older Colts ( an SP1 from 1976  and an SP2 from 1989 ) with my bushie/oly/colt/rra bastard gun.  Here's what I have found, the Colts both use AR-15 style bolt carriers and notched hammers.  The SP2 Carbine has similar ( though not as severe ) marks on the carrier cocking surface as your friends AR.  I have also noted that when I hand cycle the gun the carrier seems to hang up on the hammer just a bit....now, the SP1 is the same setup but it is uterly smooth and has no marks on it.  As a comparision my Bushie carrier cocks a round hammer ( no notch ) and is also very smooth.  The Bushie carrier is a fully supported carrier without the longer, gently angled cocking surface of the Colt.


 It just so happens that I have an EXTRA Bushie styled bolt/carrier assembly hanging around SO I put the Colt bolt head, firing pin, cam and cam pin into the EXTRA fully supported carrier and now the SP2 no longer hangs up.  Based on the pics from this thread I took a good look at my FP retaining clippie and noticed it was a bit dinged up so I used the FP retainer from the extra bolt.

 To solve your buddy's problem I think that a round profile hammer will do the trick as there will be no notch for the flange of the firing pin to hang up on.  I may be a Colt snob but I am not a Colt expert so check with the gang here to make sure you get the right hammer pin hole size, then order a replacement hammer with a fully rounded profile.  Now, there may even be a cheaper route and that would be to round off the squared notch at the top of the hammer where its scratching the carrier and hanging up on the FP.  BEFORE you do this, get  a consensus from the folks here on whether or not that is the right thing to do.  I can't see it causing any harm but check first!


 Hope this helps!!!

I had this problem once with a pre-owned Colt.  The hang-up when manually closing the bolt is caused by the M16 firing pin collar hanging up on the notched hammer.  This combination of parts: ar carrier, m16 firing pin, and ar15 hammer, causes the firing pin collar to chew up the hammer notch, which then chews up the carrier.  Also, the firing pin get bashed in to its retaining pin.

You need to replace the firing pin and retaining pin with ar15 type parts.  Then, you can clean up the hammer notch so its no longer buggered up, and maybe smooth the underside of the carrier.

Thanks for the info guys!  My friends 6721 is brand new and was purchased from a local dealer who had it as an extra LEO gun when the ban sunset.  Everything appears to be Colt original.  The bolt is marked MPC and I'm 99% sure there was a "C" stamped in the carrier.  I could be thinking of my carrier.

I was not aware that there was a difference between an AR-15 firing pin and a M-16 firing pin.  I'll get him to caliper the ring and we'll compare them later tonight.

So what some of you guys are saying is that the notch at the top of the hammer is catching the firing pin and pushing it into the retaining pin?  There doesn't appear to be any wear on the front side of the firing pin collar.  Here is how I see the process, so please correct me if I'm wrong.

1.  The hammer drops and hits the back end of the firing pin.
2.  As the carrier begins to move back, the back end of the firing pin begins to cock the hammer.
3.  While not completely cocked, the hammer rides along the bottom side of the firing pin and makes contact with the firing pin collar.  Which explains the wear on the back edge of the collar.  Even my preban carrier is showing some minor signs of wear.
4.  The carrier continues to travel backward at which point the hammer contacts the back of the carrier ramp.  The wear seems excessive on the 6721, especially on the one side.  But understandable none the less.
5.  By the time the carrier reaches it's full travel, the hammer is completely cocked.
6.  As the carrier travels forward, the only place that I can think of that would catch the firing pin and force it backward into the retaining pin would be the firing pin collar as you guys suggest.  But wouldn't you see marks on the front side of the collar?  Especially if there is enough force pushing the firing pin to bend the retaining pin in place.  As far as I can tell, the front side of the collar shows almost no wear.

I'm not saying that it's not happening that way.  But I would think that the pin would be showing more wear.  The front of the collar looks worse in the pictures than it really is.  Oh, and the top of the hammer doesn't show much wear either.

Thanks again for all your help.  I'll have my friend try to get in touch with Colt to get their opinion.

I had this exact problem with my Bushy 16" upper when I first got it.   The collar on the firing pin was getting chewed up something fierce.   I explained the problem to Bushmaster and they asked that I send the BC back in.   They returned to me a fully shrouded BC after I requested one.  No more problems.

+1 for the fully shrouded BC.

Quoted: Don’t you know Colt can do no wrong; they are perfect and make the best of everything so your friend must be stupid as are you for posting such scandalous drivel. I bet you’re lying and that isn’t a real Colt bolt, because nothing colt makes ever fails In all seriousness, it looks like either the upper or bolt is out of spec. There are plenty of Colt whores here so they will be better qualified to explain what the problem could be

Thanks for contributing absolutely nothing, MORON.

Quoted: I took another look, I am sure that is a full auto firing pin, am surprised it would function like that, never tried it myself though.  Am sure Colt's will make it right, if you call them and tell them what happened.

It does indeed look like there's an M16 firing pin in that carrier.  The wider collar on the firing pin could be smacking the hammer on the closing stroke of the action.  An M16 carrier fully shrouds that area of the firing pin.

The wear on the carrier is not out of line with what I've seen on my own rifles.

So what is the total fix for this?  Cause i just looked at my Colt bolt group and I have the same problem only worse.  way worse.  I will take some pics in a while.

Quoted: So what is the total fix for this?  Cause i just looked at my Colt bolt group and I have the same problem only worse.  way worse.  I will take some pics in a while.

Check out your firing pin.....

Roll it on the table and see if it is bent.  Does your firing pin cotter pin get bent to hell?  If not, and your firing pin is not bent, then you don't have a problem.  Some carrier wear is normal.

If your retaining pin or firing pin are damaged, then take it to an ARMORER.  Puting whacky modified parts from various manufacturers wouldn't make me feel good about the problem.

I tried to get pics but they suck so I am not going to post them.   But my problem is the same as his except the part on the left that is getting chewed up has actually made its way towards the firing pin, I mean it is sharp.  What do I do?  Shrouded carrier and different hammer?  Just carrier?  I am in panick mode.

Basically, you need an ar15 firing pin and a new cotter pin would not be a bad idea.  No wacky replacement parts there.  I like the fully shrouded carrier, but that isn't nesesary.

Don't panick, MAC!  some of my normal wear carriers have a little sharpness to the point that q-tips snag on the worn edges.  That is normal wear from the rearward movement of the cycle.

If your cotter pin and firing pin are not getting beat up, then you have no problem.

My firing pin looks fine, but the retaining pin is bent.

Who makes a shrouded carrier?  I think I am goinmg to get one and a new firing pin and new cotter and maybe a new hammer.  What hammer would be best?

ar15 carriers suck, m16 carriers are the way to go.  

RRA,LMT they have shrouded carriers although from the pic it looks like a larger collar M16 firing pin.

OK, but do you think a new hammer is needed?  If so, what kind?

Quoted: Don’t you know Colt can do no wrong; they are perfect and make the best of everything so your friend must be stupid as are you for posting such scandalous drivel. I bet you’re lying and that isn’t a real Colt bolt, because nothing colt makes ever fails In all seriousness, it looks like either the upper or bolt is out of spec. There are plenty of Colt whores here so they will be better qualified to explain what the problem could be

This idiot needs to get a life.......

Quoted: OK, but do you think a new hammer is needed?  If so, what kind?

Anyone?

Quoted: Quoted: OK, but do you think a new hammer is needed?  If so, what kind? Anyone?

 You can go with either a hammer ( cheaper ) OR a carrier IMO.  If you get a hammer you'll need a rounded hammer that has NO notch in the top surface.  Just picture that notch at the top of the Colt hammer filled in and mached to a rounded profile.  Remember to get the proper pin size!!!

 I am still wondering if just rounding that notch off wouldn't do the trick.  I am soooo tempted to try it but there is no way that I am getting any range time for WEEKS....I working 8 days a week as it is.

 Also, buy a couple extra retaining pins just for good measure....never hurts to have one on hand.

Maybe this one?

9mm parts

about halfway down...

maybe I'm way off...but seems to be a M16 style w/o hook?

I just got done diagnosing and fixing a similar problem on my 2 AR's: Retaining Pins got beat up and had to be pried out and replaced after just a few hundred rounds.

The hammer on my RRA trigger was up a little high, and needed to be stoned down in the front just a tad.

I didn't want to mess with the Stoner Trigger in my match gun, so I mic'd the firing pin flange and found it was a little oversized. It was replaced with the smallest flanged firing pin I had. There is a variation in collar sizes on all my firing pins, though none were M-16 oversized auto pins.

I also ordered a full covered, semi-auto  bolt carrier from John Holliger...and between swaping firing pins and carriers, the problem was solved.

Had a Jewell Trigger in the same gun several years ago and the problem was so bad, the entire firing pin bent up after jamming the gun.

The SR25 Stoner trigger fixed that problem as soon as I pulled the Jewell, but the reatining pin still got deformed until I changed the carrier and firing pin.

Quoted: ar15 carriers suck, m16 carriers are the way to go.

Some of the Colt AR carriers come fully shrouded, but the rear of the carrier is cut away.  

I noticed this same wear on my LW carrier back in '92.  The face of the hammer has wear on it too and the firing pin shoulder is roughed up.  Over the past 13 years, the wear has not progressed.  Nothing to be bothered about.  

After looking at the hammer again, it does look like it is the cause of the trouble.  When it was casted, no finish work was done on the face.  When I cycle the action (the hammer is cocked, but slightly contacts the carrier during motion to the rear) I feel resistance.

Some slight filing and emery cloth to polish the face of the hammer made a big difference.  The other areas that were "dinged" up  (bolt carrier ramp) were given the emery cloth treatment too.  The action feels smoother now,  the actual test is when I take it out to shoot it and see if the hammer needs more work.

Just noticed that my spare firing pin is for an M-16 (.373" dia).  Anybody want to trade me for an AR pin (.328" dia)?

I just looked at the pics provided and it is defintly an M-16 firing pin.   The flange is larger and sticks out more and is struck by the hammer, which in turn forces it against the retaining pin.   Replace the retaining pin and firing pin with an AR-15 firing pin.     This should cure your problem.   Specialized Armament Warehouse ( www.sawsales.com) has your parts in stock.

Hope this helps.

Quoted: I just looked at the pics provided and it is defintly an M-16 firing pin.   The flange is larger and sticks out more and is struck by the hammer, which in turn forces it against the retaining pin.   Replace the retaining pin and firing pin with an AR-15 firing pin.     This should cure your problem.   Specialized Armament Warehouse ( www.sawsales.com) has your parts in stock. Hope this helps.

 Might pick up a couple of those for myself!

The notch realy dosent matter with a full shroud carrier as the notch was meant to coincide with the open shroud.In case your disconector went or trigger sear wore to a point where the hammer was not being caught by the sear or disconector the notch on the hammer cathes the open part of the carrier and prevents it from running off rounds like its a full auto.The notch on RRA hammers is half the size deep than a Bushmaster hammer and the notch does not interfere with the full shrouded carrier.My carrier is RRA and so is the hamnmer in my Bushmaster.I have never had a problem with the hammer notch and the full shroud carrier although I like the look of the rounded hammer as M16 hammers are that way just the semi auto ones if you can find them are rounded with out the rear hammer hook and extra meat on the rear of the hammer where the disconector makes contact.So its not mandatory a rounded hammer be used with a full shroud.The hammer I had before it was replaced was 10 years old and had more than 10k rounds on it and it was rounded from being hit by the carrier,I just dont know wether function is improved or not by this.I do know M16 firing pins  have a larger collar and a deep hammer notch will tend to hit the collar at the same time the hammer hits the firing pin so a smaller notch hammer or no notch at all used with that firing pin and an open shroud should fix the problem of the beat up retaining pin and firing pin.I would go with a full shroud anyway then it dosent matter what hammer or firing pin.

I had this same problem recently with a DPMS carrier, the fully shrouded bolt carrier will solve the problem. But all I did was switch to a firing pin with a smaller collar. The firing pin that was causing the problems had a collar about .340", I switched it with another firing pin that had a .325" collar and that solved the problem. You could easily put the oversize firing pin in a drill press or lathe and turn the collar down to about .325 and fix the problem.

If your hammer is notched like this, remove and polish the red areas. Should take care of you problem.

Quoted: The notch realy dosent matter with a full shroud carrier as the notch was meant to coincide with the open shroud.In case your disconector went or trigger sear wore to a point where the hammer was not being caught by the sear or disconector the notch on the hammer cathes the open part of the carrier and prevents it from running off rounds like its a full auto.The notch on RRA hammers is half the size deep than a Bushmaster hammer and the notch does not interfere with the full shrouded carrier.My carrier is RRA and so is the hamnmer in my Bushmaster.I have never had a problem with the hammer notch and the full shroud carrier although I like the look of the rounded hammer as M16 hammers are that way just the semi auto ones if you can find them are rounded with out the rear hammer hook and extra meat on the rear of the hammer where the disconector makes contact.So its not mandatory a rounded hammer be used with a full shroud.The hammer I had before it was replaced was 10 years old and had more than 10k rounds on it and it was rounded from being hit by the carrier,I just dont know wether function is improved or not by this.I do know M16 firing pins  have a larger collar and a deep hammer notch will tend to hit the collar at the same time the hammer hits the firing pin so a smaller notch hammer or no notch at all used with that firing pin and an open shroud should fix the problem of the beat up retaining pin and firing pin.I would go with a full shroud anyway then it dosent matter what hammer or firing pin.

By the notch I mean like above in the hammer diagram where the red spots are.The RRA hammer is half this size.The notch was ther so it can hang up on the open bottom carrier should your disconector fail,disconector is the part inside the trigger with a spring under it.It catches the rear of the hammer"the pointe up part of the hammer under the claw" and drops it to the trigger sear which is the front polished top of the trigger assembly.The rounded bottom of the hammer in the rear where its cut rectangular catches this part of the trigger.By shroud I mean the bottom of the carrier a full shroud covers the pin so you can only see the rear projecting out an open shroud you can see the pins rear and the round collar.By rounded hammer I mean one that has no notch wich resembles a full auto hammer with out the rear hook that would be on the claw of the hammer to catch the auto sear.With a large collar firing pin think of the notch like an L backwards the top of the L-----hits the back of the firing pin while the bottom of the L____hits the collar beating it up,with closed bottom or full shroud only the rear of the firing pin gets hit and the bottom of the hammer makes no contact with the collar at all,the carrier hits it instead of the collar.RRA is for rock river arms and I use their hammers and carriers and the notch on their hammers is half as deep as the notch on a Bushmaster hammer.The way the diagram shows where to remove material is how my notched hammer looked after the years of use,it rounded on its own.Now with the full shrouded bottom the hammer dosent get beat up like that at all,sorry for the confusion the way I first replied

I got the chance to caliper both of the Colt firing pin collars that are pictured and I'm sorry to say that they are both .328".  I then measured the firing pin collar on my LMT b/c/g and that is .372".  If .372" is typical for an M-16 firing pin, then I assume that .328" is an AR-15 firing pin.  It was a good theory though.  I need x-ray vision and way to slow down time.  That would allow me to see what's going on inside this gun.

For those that are interested, the LMT bolt carrier (at least the standard one) has a fully shrouded firing pin hole.

BTW, is there a disadvantage to having a fully shrouded firing pin hole?  The only thing I can think of is some extra force being put on the hammer because it gets cocked faster.

 

Quoted: I got the chance to caliper both of the Colt firing pin collars that are pictured and I'm sorry to say that they are both .328".  I then measured the firing pin collar on my LMT b/c/g and that is .372".  If .372" is typical for an M-16 firing pin, then I assume that .328" is an AR-15 firing pin.  It was a good theory though.  I need x-ray vision and way to slow down time.  That would allow me to see what's going on inside this gun. For those that are interested, the LMT bolt carrier (at least the standard one) has a fully shrouded firing pin hole. BTW, is there a disadvantage to having a fully shrouded firing pin hole?  The only thing I can think of is some extra force being put on the hammer because it gets cocked faster.

Ooops, sorry about sending you off in the wrong direction here.  I would guess if it is not the firing pin, then must be the hammer that is defective.

Who makes a shrouded carrier? I think I am goinmg to get one and a new firing pin and new cotter and maybe a new hammer. What hammer would be best?

Hey Chewie--I like the RRA "enhanced" carrier for the money (about $100 with bolt).  SAW has Colt carriers with the shrouded FP for $150 if you're into Colt-only stuff.  If you replace the carrier, forget the hammer--you have solved the problem already.    

RRA Enhanced carrier it is!

Thanks guys.

OK, I'll chime in and mention that Oly is currently producing fully shrouded carriers with a minimum cut on the bottom to retain as much mass as possible without tripping an autosear. They can start a little tight, so lube them liberally. After throwing 300 hundred or so rounds out they smooth down nicely.

Quoted: OK, I'll chime in and mention that Oly is currently producing fully shrouded carriers. They can start a little tight, so lube them liberally.

Or as Tom the idiot would say...  "TIGHTER TOLLERANCES"!