VASCAR2 Wrote:SDW, I haven’t seen any post regarding the bolt used by PSA other than they are 6.5 Grendel with .136 bolt face. Bll Alexander chose to use the .136 bolt face to permit more room for the extractor. A typical 5.56/223 bolt has a .125 bolt face depth and the bolt length from face to tail is 2.80. Bill A lengthened the 6.5 Grendel bolt to 2.810 to make up for the .01 deeper bolt. By going to a 2.810 bolt length the 6.5 Grendel can use the same length firing pin as the 5.56/223 bolt (mil spec BCG).
If someone has a PSA 6.5 Grendel BCG which came with their upper measure the length of the bolt. Hopefully PSA did their home work and are using a 2.810 length bolt. Over the years there were a couple of examples of tolerence stacking where a bolt and firing pin had light firing pin hits. There were also a couple of situations with pierced primers because of out of spec firing pins and or bolts. These were very rare situations but when Odin released their 6.5 Grendel it was discovered they were using 2.800 length bolt with milspec firing pins. These 2.80 length bolts with milspec length firing pins resulted in excessive firing pin protrusion and pierced primers.
It is unknown if Odin Works manufactures their own 6.5 Grendel bolts or purchased bolts from another manufacturer. Brownell’s released their 6.5 Grendel BCG at about the same time as Toolcraft and both use 2.80 length bolts. If I were to purchase or use a Brownell’s, Toolcraft or Odin 6.5 Grendel bolt I’d measure the bolt and firing pin. Without measuring the firing pin and bolt length you won’t know what you have because milspec length firing pins have been shipped with the 2.80 bolts.
When LaRue 6.5 Grendel was released one forum member measured his bolt at 2.80 but later another member measured a Larue bolt from an UU kit and the bolt was 2.810. Many times manufactures will make product changes without announcing the change. To be on the safe side I’ve measured all my 6.5 Grendel bolts, firing pins and bolt face depths and all mine were within spec.
I was having primer piercings with the factory firing pin in ny radical upper. I changed it out with the firing pit from a Odin works 6.5 grendel BCG and it went away.
How do you measure the bolt to see what length I have?
I have a new PSA 20" stainless upper that I bought a month ago. If I am measuring the bolt correctly, and if my el cheapo Neiko digital caliper is accurate... the bolt measures 2.7958, and the firing pin measures 3.2645.
09-21-2018, 01:50 AM (This post was last modified: 09-21-2018, 02:03 AM by VASCAR2.)
TraderRik Wrote:I have a new PSA 20" stainless upper that I bought a month ago. If I am measuring the bolt correctly, and if my el cheapo Neiko digital caliper is accurate... the bolt measures 2.7958, and the firing pin measures 3.2645.
Soooo, what does this tell us?
You should be gtg. Your PSA Bolt is basically 2.80 and your firing pin is less than 3.270 so you should be ok. Your firing pin is roughly .01 shorter than a milspec firing pin. If you have to replace your firing pin just ensure to buy a shorter firing pin from PSA to match your PSA 6.5 Grendel bolt or buy a milspec stainless steel firing pin and reduce the length .01.
Brownell’s sell a firing pin protrusion gauge. Minimum firing pin protrusion is .028 maximum .036.
My milspec firing pins measure 3.279. Normal tolerance can vary the exact length which is referred to as tolerance stacking when two parts together don’t fit/work. Both parts being at the extreme of manufactured tolerance making parts either to long or to short.
09-21-2018, 02:40 PM (This post was last modified: 09-21-2018, 02:53 PM by SDW.)
VASCAR2 Wrote:SDW, I haven’t seen any post regarding the bolt used by PSA other than they are 6.5 Grendel with .136 bolt face. Bll Alexander chose to use the .136 bolt face to permit more room for the extractor. A typical 5.56/223 bolt has a .125 bolt face depth and the bolt length from face to tail is 2.80. Bill A lengthened the 6.5 Grendel bolt to 2.810 to make up for the .01 deeper bolt. By going to a 2.810 bolt length the 6.5 Grendel can use the same length firing pin as the 5.56/223 bolt (mil spec BCG).
If someone has a PSA 6.5 Grendel BCG which came with their upper measure the length of the bolt. Hopefully PSA did their home work and are using a 2.810 length bolt. Over the years there were a couple of examples of tolerence stacking where a bolt and firing pin had light firing pin hits. There were also a couple of situations with pierced primers because of out of spec firing pins and or bolts. These were very rare situations but when Odin released their 6.5 Grendel it was discovered they were using 2.800 length bolt with milspec firing pins. These 2.80 length bolts with milspec length firing pins resulted in excessive firing pin protrusion and pierced primers.
It is unknown if Odin Works manufactures their own 6.5 Grendel bolts or purchased bolts from another manufacturer. Brownell’s released their 6.5 Grendel BCG at about the same time as Toolcraft and both use 2.80 length bolts. If I were to purchase or use a Brownell’s, Toolcraft or Odin 6.5 Grendel bolt I’d measure the bolt and firing pin. Without measuring the firing pin and bolt length you won’t know what you have because milspec length firing pins have been shipped with the 2.80 bolts.
When LaRue 6.5 Grendel was released one forum member measured his bolt at 2.80 but later another member measured a Larue bolt from an UU kit and the bolt was 2.810. Many times manufactures will make product changes without announcing the change. To be on the safe side I’ve measured all my 6.5 Grendel bolts, firing pins and bolt face depths and all mine were within spec.
Hmm. Yeah. I can't speak on Odin Works bolts. Don't have one. Nor a Brownell's. And I don't even have a PSA 6.5G bolt. Maybe I left out the detail about buying a PSA BCG for for 5.56. And I yanked out the bolt (it's now a spare) and I put in this badboy, which I bought from Ballistic Advantage (BA) along with my barrel:
I have not measured the bolt's length. But I may as well. I do remember thinking that the FP (the one that came with the PSA BCG) seemed to protrude slightly more out of the bolt (after the 6.5G bolt swap) than say, the FPs in my other BCGs from... Anderson, DD, Bravo Co. Especially after reading a couple of threads here on the subject. I was thinking I got the dreaded "long" Toolcraft FP. It did measure out to be a little longer than one of my 'standard' pins. So I ordered a pin from Bravo, and that's what I am using now in this BCG. FP measurements are below. I pulled these numbers out of a post of mine from an earlier thread on a similar subject.
BCM pin = 3.274"
PSA pin = 3.279"
Protrusion "looks normal" now LOL But I should measure my Bolt as well, for uh, good measure. And report it here, just so we can have a record of what Ballistic Advantage is selling.
Also, I did put together a dummy round from a new, sized Hornady case and a 129gr Hornady bullet. OAL was 2.250", give or take. Dropped the bolt on it and racked it back a few times. Nothing odd happened: bolt locked up fine, no stovepipes, hah, and extraction flung the round out with a nice twirling action at about 4-5 o'clock. Same as I'd expect if doing this with a 5.56 round. So I can assume now that there's nothing wonky with my extractor.
09-21-2018, 04:19 PM (This post was last modified: 09-21-2018, 04:22 PM by WSAR15.)
Then, may I conclude the PSA also does not supply the appropriate length for the 6.5 Bolt II?
I just ordered one of their 18" uppers on sale, so I'll need a new bolt and firing pin.
Hmmm... If I understand it all - and someone please correct me if this is wrong - the bolt & pin length don't dictate whether or not the bolt is a "type 2". Rather, it's the size of the bolt face that does (and the barrel throat.) The shorter Toolcraft and Odin Works bolts are certainly type 2, as is the PSA.
TraderRik Wrote:Hmmm... If I understand it all - and someone please correct me if this is wrong - the bolt & pin length don't dictate whether or not the bolt is a "type 2". Rather, it's the size of the bolt face that does (and the barrel throat.) The shorter Toolcraft and Odin Works bolts are certainly type 2, as is the PSA.
Thsts how i understand it bolt and fireing pin length dont have anything to do with tge type 2 bolt refrence.
Type 2 pertains the the bolt face depth, grendel bolt is and always will be .136 where the 264lbc chamber started out and mostly still is used with a bolt that has a .125 bolt face depth.
For a true grendel bolt that uses a mil spec length fireing pin buy them from AA,Lijia,PF,JP and Maxim Firearms.
I spend my money with these suppliers I know my purchase will be correct and product built to spec.
A5BLASTER Wrote:Toolcraft and odion 6.5 grendel bolts use a shorter firing pin due to the bolt being a different length from mil spec.
AA,JP maxim firearms have bolts and proper sized parts for sale. Don't try and save a buck cause it's just going to burn you.
Dammit! I decided not to go with a Toolcraft because of the firing pin issue. So I figured Odin was a good way to go. Ordered it, got here yesterday...and now I see this. Oh well, guess Ill run it anyways.
There is no problem with a 2.800” bolt with a bolt face of .136. The only issue is the firing pin protrusion if a 3.279” length firing pin (milspec) is used. If I were betting I’d say Toolcraft, Odin, Brownell’s, PSA are getting their bolts from the same source. With non disclosure agreements we’ll probably never know the actual manufacturer of the 2.80 6.5 Grendel bolts.
It aggravates me that the different length bolts are being used because it just adds to confusion. Once manufacturers started manufacturing AR-15’s in other calibers there is no specific standard. A 2.80” bolt if properly manufactured should last as long as a 2.81” 6.5 Grendel bolt. With no milspec standard a manufacturer can use whatever safe design they choose. Similar situation with SAAMI Spec chamber, 264 LBC, 6.5 Sporter, Grendel 1 or Grendel II.
I think it is wise to measure your bolt length and firing pin especially if you get deep primer strikes or pierced primers.
I really don’t know the acceptable tolerance for most manufacturers making firing pins. A 2.80” bolt should use a firing pin 3.269” long. A 2.810” bolt work with 3.279” milspec firing pin.
But ya know what guys? I have been shooting ARs for a number of years, and my buddies have as well. We were talking about this, and none of us have ever broken a firing pin, or a bolt. I'm sure it happens; but is it really a common problem? Even so, I keep a spare BCG for my 5.56 ARs; and I have now ordered a spare BCG for my Grendels.
09-22-2018, 02:52 AM (This post was last modified: 09-22-2018, 01:43 PM by SDW.)
Well I found out some good news this evening. We can add the Ballistic Advantage 6.5 Grendel bolts to the "good" list, i.e. the list that includes Maxim, JP, Lilja, and the others. My BA bolt also measures 2.810".
I have read this thread from start to finish, including the linked thread, and just to really muddy the waters...I have 3 BCGs from PSA, one has a branded Toolcraft carrier, the other 2 are PSA premium and the carriers just have 6.5 on them. All 3 bolts are the 'longer' bolts using the 3.279 firing pin. 2 PSA bolts measure 2.810, the Toolcraft measures 2.809.
CWOZ Wrote:I have read this thread from start to finish, including the linked thread, and just to really muddy the waters...I have 3 BCGs from PSA, one has a branded Toolcraft carrier, the other 2 are PSA premium and the carriers just have 6.5 on them. All 3 bolts are the 'longer' bolts using the 3.279 firing pin. 2 PSA bolts measure 2.810, the Toolcraft measures 2.809.
You should be gtg CWOZ. The Toolcraft bolt is fine 2.809” is only .001” off which is within tolerance. There is a greater tolerance of AR-15 firing pin overall length. I’ve read maximum FP overall length is 3.280” with a tolerance of -.009”.
The firing pin protrusion is the critical concern and needs to be in spec. The minimum FP protrusion is .028” and maximum .036”. The .008” is the tolerance built into the spec for variations in bolt and firing pin lengths. With the three firing pins you have being 3.279” your fine with the 2.809” length bolt, your well within the tolerance envelope and should be gtg.
No vendor specifically sell the shorter firing pins to my knowledge. I suggest you buy a Stainless Steel mil spec firing pin. Measure the firing pin then you’ll know how much material to remove. As an example if the FP measures 3.279 remove .01 so it is 3.269. Firing pins have a greater variation in lengths than you’d think. It doesn’t hurt to measure the bolt and firing pin when assembling a new 6.5 Grendel.
