I have a DPMS BCG in my DPMS/IRA .308 build. I ran it through roughly 200 rds of M118LR during a range session recently. When I disassembled it yesterday to clean I had a hard time removing the firing pin retaining pin. When I did get it out I found it to be bent. Can anyone provide input or insight as to why this is occurring?
- Thread starter Cyclops
- Start date
Re: Bent firing pin retaining pin
Is your firing pin a cotter key style or the machined style? Most likely an ammo related issue.
Is your firing pin a cotter key style or the machined style? Most likely an ammo related issue.
Re: Bent firing pin retaining pin
I'm guessing the carrier in your rifle is not shrouded . Meaning the firing pin is contacting the hammer on the firing cycle . These are the only times that I have seen slightly bent retaining pins . I'm guessing it looks like the one on the left .
I'm guessing the carrier in your rifle is not shrouded . Meaning the firing pin is contacting the hammer on the firing cycle . These are the only times that I have seen slightly bent retaining pins . I'm guessing it looks like the one on the left .
Re: Bent firing pin retaining pin
Put up a picture. I'm pretty sure the retaining pins have a slight bend to them, I know mine does.
Put up a picture. I'm pretty sure the retaining pins have a slight bend to them, I know mine does.
Re: Bent firing pin retaining pin
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Cyclops</div><div class="ubbcode-body">It's the machined one. What do you mean ammo issue? </div></div>
The ammo you are shooting could be on the high end of the pressure scale. The fit of your bolt (tail) and the carrier may be loose allowing excessive gas through. The first thing that the gas runs into is the stop flange on your firing pin.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Cyclops</div><div class="ubbcode-body">It's the machined one. What do you mean ammo issue? </div></div>
The ammo you are shooting could be on the high end of the pressure scale. The fit of your bolt (tail) and the carrier may be loose allowing excessive gas through. The first thing that the gas runs into is the stop flange on your firing pin.
Re: Bent firing pin retaining pin
I've got a little AR15 that bends that firing pin retaining pin (no, they are straight as and arrow when new). I'm going to check the carrier to see if it exposes the firing pin like that first one in your example.
Thanks for the picture.
Oh, I have several AR15's but only that one requires pin replacement every now and then.
I've got a little AR15 that bends that firing pin retaining pin (no, they are straight as and arrow when new). I'm going to check the carrier to see if it exposes the firing pin like that first one in your example.
Thanks for the picture.
Oh, I have several AR15's but only that one requires pin replacement every now and then.
Re: Bent firing pin retaining pin
Its the ammo. I had same problem with my 6.5 <span style="text-decoration: line-through">Grendel</span> Creedmoor until I went to this retaining pin:
Click Here to buy one at MidwayUSA
No more bent pin worries.
Its the ammo. I had same problem with my 6.5 <span style="text-decoration: line-through">Grendel</span> Creedmoor until I went to this retaining pin:
Click Here to buy one at MidwayUSA
No more bent pin worries.
Re: Bent firing pin retaining pin
My BCG is not open it's shrouded, so I don't think my hammer is hitting the pin.
M Gale,
I don't see myself shooting anything other than M118LR or M852 through it. Do you think that's a huge problem? That being said will the pin continue to bend until it breaks? If so should I just maintain extra retaining pins around or is there another fix?
Bronco Buster,
That's the pin I currently have in mine that bent.
My BCG is not open it's shrouded, so I don't think my hammer is hitting the pin.
M Gale,
I don't see myself shooting anything other than M118LR or M852 through it. Do you think that's a huge problem? That being said will the pin continue to bend until it breaks? If so should I just maintain extra retaining pins around or is there another fix?
Bronco Buster,
That's the pin I currently have in mine that bent.
Re: Bent firing pin retaining pin
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Cyclops</div><div class="ubbcode-body">My BCG is not open it's shrouded, so I don't think my hammer is hitting the pin.
M Gale,
I don't see myself shooting anything other than M118LR or M852 through it. Do you think that's a huge problem? That being said will the pin continue to bend until it breaks? If so should I just maintain extra retaining pins around or is there another fix?
Bronco Buster,
That's the pin I currently have in mine that bent. </div></div>
If you are set on using M118LR, an adjustable gas block and a high quality firing pin retaining pin should be considerations.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Cyclops</div><div class="ubbcode-body">My BCG is not open it's shrouded, so I don't think my hammer is hitting the pin.
M Gale,
I don't see myself shooting anything other than M118LR or M852 through it. Do you think that's a huge problem? That being said will the pin continue to bend until it breaks? If so should I just maintain extra retaining pins around or is there another fix?
Bronco Buster,
That's the pin I currently have in mine that bent. </div></div>
If you are set on using M118LR, an adjustable gas block and a high quality firing pin retaining pin should be considerations.
Re: Bent firing pin retaining pin
One thing that can happen on SR-25's is it is possible to put the firing pin in not fully seated and the firing pin retaining pin can go home, retaining the firing pin in a non-firing position.
When the hammer falls in this setting, the firing pin thumps into the firing pin retaining pin, and will often bend it.
I'm pretty sure that the DPMS gun is still based off the early SR-25. Anyway that you did this and did not notice the bend prior to shooting?
We get the occasional M110 back from the Army for this reason (or often a note saying 'gun does not fire' as the firing pin was still in the 'neutral' position...)
One thing that can happen on SR-25's is it is possible to put the firing pin in not fully seated and the firing pin retaining pin can go home, retaining the firing pin in a non-firing position.
When the hammer falls in this setting, the firing pin thumps into the firing pin retaining pin, and will often bend it.
I'm pretty sure that the DPMS gun is still based off the early SR-25. Anyway that you did this and did not notice the bend prior to shooting?
We get the occasional M110 back from the Army for this reason (or often a note saying 'gun does not fire' as the firing pin was still in the 'neutral' position...)
Re: Bent firing pin retaining pin
Kevin,
That's possible, but I had no problems firing it. Maybe it happened during a dry fire after reassembly at some point, is that possible?. I'd be really upset with myself if that is the case as I'm pretty familiar with the SR25, MK11, M110.
Kevin,
That's possible, but I had no problems firing it. Maybe it happened during a dry fire after reassembly at some point, is that possible?. I'd be really upset with myself if that is the case as I'm pretty familiar with the SR25, MK11, M110.
Re: Bent firing pin retaining pin
So I've been in touch with a DPMS rep and he also states that it's the ammo. Says the primers on M118LR are extra hard and it's causing the bent pin. My question: Isn't this the same BCG submitted for the M110 SASS trials? if so how the hell can it not be rated for M118LR? Still waiting for an answer.
So I've been in touch with a DPMS rep and he also states that it's the ammo. Says the primers on M118LR are extra hard and it's causing the bent pin. My question: Isn't this the same BCG submitted for the M110 SASS trials? if so how the hell can it not be rated for M118LR? Still waiting for an answer.
Re: Bent firing pin retaining pin
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Cyclops</div><div class="ubbcode-body">So I've been in touch with a DPMS rep and he also states that it's the ammo. Says the primers on M118LR are extra hard and it's causing the bent pin. My question: Isn't this the same BCG submitted for the M110 SASS trials? if so how the hell can it not be rated for M118LR? Still waiting for an answer. </div></div>
Can't wrap my arms around this one. How can a hard primer cup have any affect on the firing pin. Can you post some pictures of fire brass so we can see if there any physical manifestations of over pressure?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Cyclops</div><div class="ubbcode-body">So I've been in touch with a DPMS rep and he also states that it's the ammo. Says the primers on M118LR are extra hard and it's causing the bent pin. My question: Isn't this the same BCG submitted for the M110 SASS trials? if so how the hell can it not be rated for M118LR? Still waiting for an answer. </div></div>
Can't wrap my arms around this one. How can a hard primer cup have any affect on the firing pin. Can you post some pictures of fire brass so we can see if there any physical manifestations of over pressure?
Re: Bent firing pin retaining pin
Unfortunately i don't have any of the fired brass. I had no malfunctions and I don't reload so I had no reason to keep it. Below is a cut & paste of my back and forth with DPMS:
"User/Date Message
Customer
9/10/2012 5:15:33 PM The firing pin retaining pin on my LR308 bolt is bent after only firing 350 rds of M118LR. Is this normal? What causes this? Is there a fix?
Staff (Mark Imolte)
9/10/2012 5:17:53 PM that is caused from the extra hard military primers they use there is alot of extra force with that ammo
Customer
9/11/2012 6:22:06 AM Is there a fix? Do you sell an improved pin?
Staff (Mark Imolte)
9/11/2012 9:47:14 AM there is realy no improved retaing pin or anything to fix it. it is all ammo related
Customer
9/11/2012 11:10:23 AM I guess I'm confused. Wasnt this the same bolt design submitted for the SASS trials?
Staff (Mark Imolte)
9/11/2012 11:17:52 AM has nothing to do with the bolt at all. it is a retaining pin as you stated. the ammo you are useing is made for a machine gun and not a rifle. the primmers are hardened to keep from cook offs
Staff (Mark Imolte)
9/11/2012 11:20:46 AM it may be desinged for the snipeing application but the primers are harder for cross use in the feild.
Customer
9/11/2012 5:40:41 PM I'm a former Army Sniper Instructor and currently a federal LE firearms instructor. I'm very familiar with most AR .308 semi auto platforms and haven't seen this before I used one of your products. Is this a common problem across the board or is this something specific to DPMS? I'm not trying to come across as argumentative, i'm sincerely curious.
Staff (Mark Imolte)
9/11/2012 5:51:38 PM i have never seen a bent retaining pin in any rifle. i have one sitting next to me that has over 6000 rounds of 150 grain remmington UMC ammo through it and not even been cleaned. or a gas rine changed. my own personal rifle has 563 rounds with out anything changed. we use alot of 308 rifles in shows/live shoots and we have never seen a bent retaining pin. factory produced ammo has alot to do with it also
Unfortunately i don't have any of the fired brass. I had no malfunctions and I don't reload so I had no reason to keep it. Below is a cut & paste of my back and forth with DPMS:
"User/Date Message
Customer
9/10/2012 5:15:33 PM The firing pin retaining pin on my LR308 bolt is bent after only firing 350 rds of M118LR. Is this normal? What causes this? Is there a fix?
Staff (Mark Imolte)
9/10/2012 5:17:53 PM that is caused from the extra hard military primers they use there is alot of extra force with that ammo
Customer
9/11/2012 6:22:06 AM Is there a fix? Do you sell an improved pin?
Staff (Mark Imolte)
9/11/2012 9:47:14 AM there is realy no improved retaing pin or anything to fix it. it is all ammo related
Customer
9/11/2012 11:10:23 AM I guess I'm confused. Wasnt this the same bolt design submitted for the SASS trials?
Staff (Mark Imolte)
9/11/2012 11:17:52 AM has nothing to do with the bolt at all. it is a retaining pin as you stated. the ammo you are useing is made for a machine gun and not a rifle. the primmers are hardened to keep from cook offs
Staff (Mark Imolte)
9/11/2012 11:20:46 AM it may be desinged for the snipeing application but the primers are harder for cross use in the feild.
Customer
9/11/2012 5:40:41 PM I'm a former Army Sniper Instructor and currently a federal LE firearms instructor. I'm very familiar with most AR .308 semi auto platforms and haven't seen this before I used one of your products. Is this a common problem across the board or is this something specific to DPMS? I'm not trying to come across as argumentative, i'm sincerely curious.
Staff (Mark Imolte)
9/11/2012 5:51:38 PM i have never seen a bent retaining pin in any rifle. i have one sitting next to me that has over 6000 rounds of 150 grain remmington UMC ammo through it and not even been cleaned. or a gas rine changed. my own personal rifle has 563 rounds with out anything changed. we use alot of 308 rifles in shows/live shoots and we have never seen a bent retaining pin. factory produced ammo has alot to do with it also
Re: Bent firing pin retaining pin
I'm not sure how on earth ammo could affect it. Frankly the firing pin should bottom out on the tail of the bolt regardless of primer. Is it bent in or bend backwards?
The only other way I see them getting bent is if someone re-installs the bolt carrier and lets the firing pin retaining pin slide out - and then rams it into the upper.
The firing pin weight is minuscule - so the inertia of it cycling should not have any consequence, unless the bolt carrier velocity in the gun is exceptionally high.
As example I have 15k from my first barrel, and a further 9200 (ish) on my second barrel on my personal SR-25 using the same carrier - and no firing pin retaining pin bend issues. Despite the unusual types of ammo I can shoot, and the addition of suppressors.
I'm not sure how on earth ammo could affect it. Frankly the firing pin should bottom out on the tail of the bolt regardless of primer. Is it bent in or bend backwards?
The only other way I see them getting bent is if someone re-installs the bolt carrier and lets the firing pin retaining pin slide out - and then rams it into the upper.
The firing pin weight is minuscule - so the inertia of it cycling should not have any consequence, unless the bolt carrier velocity in the gun is exceptionally high.
As example I have 15k from my first barrel, and a further 9200 (ish) on my second barrel on my personal SR-25 using the same carrier - and no firing pin retaining pin bend issues. Despite the unusual types of ammo I can shoot, and the addition of suppressors.
Re: Bent firing pin retaining pin
When our department first adopted patrol rifles we issued dpms and had exactly the same problem... bent firing pin retaining pinss, among other problems as well. We finally scrapped the dpms and went to Colt 6920s. Same ammo, no more problems.
I always suspected the problem to excessive gas pressure accelerating the bcg. Seems kinds fishy that your dpms is doing the same thing.
When our department first adopted patrol rifles we issued dpms and had exactly the same problem... bent firing pin retaining pinss, among other problems as well. We finally scrapped the dpms and went to Colt 6920s. Same ammo, no more problems.
I always suspected the problem to excessive gas pressure accelerating the bcg. Seems kinds fishy that your dpms is doing the same thing.
Re: Bent firing pin retaining pin
you shooting suppressed at anytime lately without turning the gas down?
My std lr-308 broke some shit that had to be replaced due to running my 308 cans on it with the std gas block. But it really threw the shit out of some brass while it was running.
you shooting suppressed at anytime lately without turning the gas down?
My std lr-308 broke some shit that had to be replaced due to running my 308 cans on it with the std gas block. But it really threw the shit out of some brass while it was running.
Re: Bent firing pin retaining pin
I'm not sure which way the pin is bending forward or back. It's not been shot suppressed, like I said strictly 350 rds of M118LR through a Criterion 18.5" barrel. I will admit that DPMS has been very good on communicating with me on this. They offered to replace the pin, but I don't need them to do that as I can buy my own pin. I just want to know that my gun is safe to fire and what the exact cause may be. I really do appreciate all the feedback. I'll be putting up a pic of the pin as soon as I can but after I send one to DPMS.
I'm not sure which way the pin is bending forward or back. It's not been shot suppressed, like I said strictly 350 rds of M118LR through a Criterion 18.5" barrel. I will admit that DPMS has been very good on communicating with me on this. They offered to replace the pin, but I don't need them to do that as I can buy my own pin. I just want to know that my gun is safe to fire and what the exact cause may be. I really do appreciate all the feedback. I'll be putting up a pic of the pin as soon as I can but after I send one to DPMS.
