308 / 6.5CM FP tip sizes, and the variety I found.

AR/M4 Beyond 5.56/.223
1

Posted this on numerous forums… hoping Google searches would help others.

And I hope the pics show… however I have had problems here trying to post pics.

This is gonna be about the various FP tip sizes, and styles and bolt FP holes I have found.

IMHO… All manufacturers should post FP tip sizes and bolt FP hole diameters… Yeah I know… Good Luck.

Much like everything else in the Non- Mil-spec world of Large Frame AR’s ( LFAR ) … firing pins and bolt face FP holes can vary by quite a bit.

I am posting so someone can hopefully avoid using / purchasing a incorrect FP size.

This is not a be all list , but is some of the brands I have bought and measured… Please NOTE, the FP style also varies… IE , Tapered v. standard.
Tapered on the left… standard on the right… the middle is in the pic because of the less than squared of edges at the rings.
https://www.ar15.com/media/mediaFiles/171545/IMG_1041-638186.jpg

I will say , and to cut to the chase… try to buy a brand bolt that comes with a firing pin.

Using a wrong size FP tip size , in a poorly matched bolt FP hole diameter will cause excessive primer cratering and primer flow.

Measurements were done with a Pin gauge set and caliber.

For the “most” part, “standard” 308 BCG’s and bolts ( Non HP ) come with a approximate FP tip size of .076-.079 and bolt FP hole of .080-.083

My List of measured “308” FP tips and Bolt Hole sizes…

PSA / Toolcraft 308 BCG… FP tip size… .077" , bolt FP hole… .081
10ea PSA FP measured… varied between .076" ( 2ea ) .077" ( 7ea )and .079" ( 1ea )
Standard style. ( Non Tapered )

Please NOTE… the PSA dual ejector 6.5CM BCG uses a smaller HP FP tip size . More later

Links provided to be specific.
https://palmettostatearmory.com/psa-pa10-308-nitride-bolt-carrier-group-516446490.html
https://palmettostatearmory.com/psa-pa10-308-nickel-boron-bolt-carrier-group.html
https://palmettostatearmory.com/308-firing-pin.html

Lantac 308 FP , Nib 308 Bolt, and Nitrated 308 bolt, … .076" FP tip size ( 4ea ) .081" Bolt FP hole on both… these are sold as “spare parts”.
Standard style. ( Non Tapered )

PLEASE note… the Lantac ENHANCED BCG uses a different FP tip size and Bolt face FP hole !! ( More later )

https://www.lantac-usa.com/product-page/lantac-308-7-62-bolt-choose-finish-nib-qpq
https://www.lantac-usa.com/product-page/lantac-308-7-62-firing-pinFP

RTB Blem 308 BCG ( Toolcraft ? ) … .076" FP tip size,… .080" bolt face FP hole.
Non tapered FP.
Link no longer available

Others measured info…

Fulton Armory actually shows a 308 Bolt for DPMS pattern… for use with a .078" FP
https://www.fulton-armory.com/bolttitanstripped.aspx
https://www.fulton-armory.com/bolttitanstripped-2.aspx
https://www.fulton-armory.com/firingpinchrometitan.aspx

msgriff… “The original DPMS LR-308 bolts were a 0.080” bolt face firing pin orifice with a 0.076" firing pin tip diameter."
Non tapered.

Top O’ Texas tapered v. standard profile FP photo… Some of the tip sizes vary on the Tapered FP and Standard profile.
https://www.ar15.com/media/mediaFiles/171545/IMG_20231203_130006-3242555.jpg

2

A odd ball in the middle… JP Enterprises “Enhanced” 308 bolt and FP … NOT The HP JP setup.

IMHO, use of the JP enhanced FP in a “DPMS” typical bolt … will induce primer flow / cratering.

Again… buy and use your FP and Bolt from the same manufacturer… and you will be just fine.

While JP is a “standard” default for HP Bolts and FP’s… the also sell a “standard” “Enhanced” 308 bolt and FP.
JP standard Enhanced FP ( 3ea ) .0735" … both the Titanium and standard
I didn’t order the Bolt for these… but given JP’s OCD, Lol… I would imagine a NON HP Bolt face hole of around .077" ish.

https://jprifles.com/buy.php?item=JPEB-308
https://jprifles.com/buy.php?item=JPFP-308
https://jprifles.com/buy.php?item=JPFP-308TI

3

Small Diameter / HP setups… Both Tapered and Standard profile FP.

PSA / Toolcraft 6.5CM Dual ejector BCG… FWIW, my first one of these comes from May 2018. And the latest from a month ago.
Tapered SD Tip FP… .068 and .069" , Bolt face FP hole… .071"
https://palmettostatearmory.com/psa-nitride-6-5-creedmoore-bcg-with-double-ejector.html

PSA Single ejector 6.5CM …
Tapered FP, … SD Tip size… .067" … bolt face hole… .070"
Bought years ago … so no link.

CMC / Santan complete 308 BCG ( with 3 exhaust ports on the carrier , “Suppressor Optimized” , single ejector )
Tapered FP SD Tip… .067"… bolt face FP hole… .070"
https://cmctriggers.com/product/cmc-ar15-bolt-carrier-group-suppressor-optimized-milspec-black-nitride-308/

Lantac “Enhanced complete 308 BCG”… single ejector, “forward facing gas ports” w/ Small Diameter FP Tip size and Bolt face hole.
NOTE… the The Lantac sold Bolt and FP I mentioned in the first post… DO NOT interchange parts, with this Bolt and FP tip size … one or the other Bolts and FP’s most be used with the other.
You can use the the other mentioned individual Lantac Bolt Spare parts, and FP , with the carrier. But the FP tip sizes matter.
As in … the Larger tip sized FP won’t work with the “Enhanced” bolt face small diameter hole.
Tapered SD FP tip size… ( 2x ) .067… Bolt face FP hole… .070"
https://www.lantac-usa.com/product-page/enhanced-bcg-full-auto-style-223-5-56-nitrided

Rubber City Armory…
.066" tip size with a regular shank. ( Non Tapered )
https://www.ar15.com/media/mediaFiles/171545/IMGRCA_0221-3242658.jpg
https://rubbercityarmory.com/product/firing-pin-for-308-hp/
“Engineered specifically for the High Pressure 308 bolt face.”
https://rubbercityarmory.com/product/308-win-multi-hp-calibers-bolt-firing-pin/

2ea spare tapered SD FP tip sizes… I have little idea where I bought these years ago…
.068" and .069" tip size.

Recently bought Headspaced to barrel bolt and FP to a Craddock Precision RTR 308 Barrel…
Tapered SD FP tip size… .067" , Bolt face FP hole size… .071"

.

Other folks info… along with interesting comments.

“Cascade Hemi” probably Toolcraft… Tapered SD FP tip… .0675", Bolt face tip hole… .069"
Also from Cascade Hemi… Here is the No Name Low Mass bolt/BCG in the picture above:
https://www.righttobear.com/lightweight-ar10-dpms-pattern-bcg-308-bolt-carrier-group-black-nitride/

“NtxGlock” “Noveske sent me a headspaced hp bolt but no firing pin”… "Noveske told me they do not sell individual pins and they sourced that bolt from Rubber City Armory… I have sent Rubber City Armory a email. No reply yet. I did get another dual ejector bolt today w/pin from them (RCA).

Update: Rubber City Armory called me this afternoon. The tech told me that they do NOT sell AR10 bolts to Noveske, only 5.56 bolts. So, I will get back with Noveske. Jeez."

Top O’ Texas… “Also, the design keeps you from using a tapered pin in a non-hp bolt and vice versa. I can’t say that about all hp bolts/fp’s, only the few I have.”
I haven’t checked this out, yet… but…

FWIW… I have yet to see the Tapered SD FP tip size for sale by itself. HOWEVER… I do have 2 spares, Lol
I have some of the Toolcraft AR10 Small Diameter Firing Pin, on back order.

4

After receiving the Toolcraft SD FP tip size… I will update the thread.

And as mentioned… hopefully this can help others that want spare parts.

I have also e-mailed Craddock Precision, asking where they source their supplied headspaced bolt and Tapered FP.

For anyone with more measurements… please add your info !!

Thanks ahead of time

5

Great thread!

6

Great info, thanks for taking the time.

7

Thanks goodness. Finally somebody understands my ar-10 firing pin agony. I have been looking for FP with oversized tip with no avail. It would be simple. I will fit the tip to the hole.

Thanks for the list. Looks like PSA toolcraft has the thickest tip of 0.077". I’m getting one for myself.

Under sized FP or oversized hole in the bolt is epic in AR-dom. A lot of brass I pick up at range have cratered or even pierced primer.

-TL

Sent from my SM-N960U using Tapatalk

8

I am glad this helped someone !!

And more info

Azimuth / Aero Precision Nitrided 308 / 7.62 BCG Single Ejector

To Aero’s credit they at least publish a comment concerning the size of the firing pin hole. “firing pin hole diameter is reduced to .070”

TAPERED SD FP tip size… .068" … Bolt face hole… .070"

https://www.aeroprecisionusa.com/308-bcg-black-nitride

https://www.ar15.com/media/mediaFiles/171545/IMG_0268-3248462.jpg

Tell tale, rounded gas key ends of the Azimuth 308 BCG…
https://www.ar15.com/media/mediaFiles/171545/IMG_0265-3248463.jpg

Slab Side of the Azimuth / Aero nitride 308 BCG…
https://www.ar15.com/media/mediaFiles/171545/IMG_0267-3248464.jpg

https://www.ar15.com/media/mediaFiles/171545/IMG_0266-3248466.jpg

9

I am glad this helped someone !!

And more info

Azimuth / Aero Precision Nitrided 308 / 7.62 BCG Single Ejector

To Aero’s credit they at least publish a comment concerning the size of the firing pin hole. “firing pin hole diameter is reduced to .070”

TAPERED SD FP tip size… .068" … Bolt face hole… .070"

https://www.aeroprecisionusa.com/308-bcg-black-nitride

https://www.ar15.com/media/mediaFiles/171545/IMG_0268-3248462.jpg

Tell tale, rounded gas key ends of the Azimuth 308 BCG…
https://www.ar15.com/media/mediaFiles/171545/IMG_0265-3248463.jpg

Slab Side of the Azimuth / Aero nitride 308 BCG…
https://www.ar15.com/media/mediaFiles/171545/IMG_0267-3248464.jpg

https://www.ar15.com/media/mediaFiles/171545/IMG_0266-3248466.jpg

10

I ended up ordering 2 FPs from Fulton armory. They have 0.078” tips, and are quite affordable. It will give second life to my old bolt with 0.081” hole.

-TL

Sent from my SM-N960U using Tapatalk

11

tangolima, if possible , after you receive the Fulton Armory 308 FP’s , could you measure the tip size ? Just to confirm the .078"

And I just realized, I never posted the Rubber City Armory ".308 Win+ Multi HP Bolt and firing pin info.

Proprietary SD Non-Tapered FP… .066" , Bolt face hole… .071"

https://rubbercityarmory.com/product/308-win-multi-hp-calibers-bolt-firing-pin/

https://www.ar15.com/media/mediaFiles/171545/IMG_HPboltpin-3248609.jpg

12

double tapped

13

Certainly.

0.066” pin in 0.071" has 0.005” slop. I’m afraid you will see premature cratered primers. I want to have <0.002" slop. Traditionally a gunsmith would bush the bolt’s pin hole or retip the FP for that.

-TL

14

Agreed… I’m not sure what RCA was thinking with that much “gap”.

15

My take. Manufacturers go to smaller tips to reduce misfires. They don’t want to tighten the slop as it will affect production yield. Most users don’t care about primer cratering as long as no piercing.

In my case, cratered primers bother me. I don’t have misfire problem. My hammer spring has full power.

-TL

Sent from my SM-N960U using Tapatalk

16

Received the FPs, and I’m not happy. Both pins have diameter of 0.075” exactly, instead of 0.078" advertised. I have no use of them. I will write them to demand a refund.

Disappointed. I thought Fulton still had some reputation left.

-TL

PS. I will ask for an exchange first.
PPS. Fulton replied. Pin diameter 0.075”-0.076”, not 0.078”. They will correct product description error. Return for full refund. I have to pay for postage going back though. Not ideal but ok.

Sent from my SM-N960U using Tapatalk

17

Well… that sucks. That is part of my reasoning for starting this thread. WAY to much variation in tip sizes. I wonder how many people get crated primers, from the wrong tip size.

FWIW…
I also contacted Aero, asking if they sell the Tapered SD FP as a replacement part.

And while Aero CS was prompt and very helpful… they do not sell it separately.

For that matter… ( and I am sorry to say this ) “one of the techs” recommended buying a replacement from some of the above listed places. NONE of which would have been correct sized or style ( tapered ) . As in to big ( stuck ) and way to small. ( bad primer cratering, if not pierced primers )

It is sad the e-mail contact, while doing his best to help, got piss poor info from “one of the techs”… someone that should know better.

18

Recently bought Headspaced to barrel bolt and FP to a Craddock Precision RTR 308 Barrel…
Tapered SD FP tip size… .067" , Bolt face FP hole size… .071"

Craddock Precision says… ( via e-mail ) “We get all of our Bolts/BCGS/Firing Pins from Azimuth”

Now… since I have seen the Tapered SD FP in many other BCG’s, I really don’t know if Azimuth makes them.

19

I actually have been looking for FP with oversized (stuck) tip such that I can fit to my bolt with oversized (0.081") FP holes. Surprisingly everywhere I asked people didn’t get what I was trying to do. What’s considered of gunsmithing 101 for some reason is exception to AR in their mind. They talked on and on about the gas system like FP fit has anything to do with it.

There aren’t many AR-10 on range, but I have picked up a lot of 5.56 brass with cratered primers, most, if not all, are factory ammo. Looks like manufacturers have been liberal on tolerances to keep production yield high. With a stuck FP a customer will roll on floor whining. Cratered primers? Meh, he’s happy as long as no pierced primers.

-TL

Sent from my SM-N960U using Tapatalk

20

Are you looking for a “normal” non-tapered type ? And which specific tip size ?
I would be willing to send you one of mine , provided the tip size, I have on hand , meets your needs.

Free of charge.