AXMC 338 Lapua to 300 PRC Conversion Issue

[dfloomis]

I recently picked up an AXMC in 338 Lapua. My local range does not allow anything over 300 caliber, so I also purchased the 300 bolt body (part 20013) and a 300 PRC barrel (part 2527073BL). After the conversion to 300 PRC, the pin is either not or barely making contact with the primer. Does this setup need the small firing pin or is this most likely a headspacing issue with the barrel?

 

[IK6243]

Shouldn't be a LFP vs SFP issue.

Check the firing pin protrusion with the magnum bolt body vs the Lapua magnum bolt body, and also the headspace if you have gauges. Issue could be one or both.

 

[Kiba]

Firing pin protrusion should not have to be adjusted between bolt bodies.

However, if you had a 1.6mm small firing pin 338 bolt and firing pin already, it will not work with the large firing pin #20013 300wm bolt you purchased.

If you want to confirm, pull your current firing pin assembly out and measure, or look at the picture below. 1.6mm small firing pin on left, 2.0mm large on right. An AXMC should have came with the 2.0mm firing pin by default, but someone may have swapped it out and I've heard rumors that some late production AXMCs came with 1.6mm firing pins from AI.

If it's not a firing pin mismatch issue, it's probably a chamber issue with the 300 barrel.

 

[dfloomis]

Firing pin protrusion should not have to be adjusted between bolt bodies.

However, if you had a 1.6mm small firing pin 338 bolt and firing pin already, it will not work with the large firing pin #20013 300wm bolt you purchased.

If you want to confirm, pull your current firing pin assembly out and measure, or look at the picture below. 1.6mm small firing pin on left, 2.0mm large on right. An AXMC should have came with the 2.0mm firing pin by default, but someone may have swapped it out and I've heard rumors that some late production AXMCs came with 1.6mm firing pins from AI.

View attachment 8781673

If it's not a firing pin mismatch issue, it's probably a chamber issue with the 300 barrel.

Thank you - That is the issue. This is a new AXMC LE version and it did come with the SFP and not the large. Is there a chart anywhere detailing which pin is needed for which caliber?

 

[Kiba]

Thank you - That is the issue. This is a new AXMC LE version and it did come with the SFP and not the large. Is there a chart anywhere detailing which pin is needed for which caliber?

If you have a small 1.6mm firing pin you need all 1.6mm small firing pin bolt bodies.

You can also buy a complete 2.0mm firing pin assembly to use with that new large firing pin 300wm bolt body you have, but that's $500+. I would send the large firing pin 300wm bolt back and exchange it for a 1.6mm small firing pin 300wm bolt, #27777.

 

[Jrb572]

If you have a small 1.6mm firing pin you need all 1.6mm small firing pin bolt bodies.

You can also buy a complete 2.0mm firing pin assembly to use with that new large firing pin 300wm bolt body you have, but that's $500+. I would send the large firing pin 300wm bolt back and exchange it for a 1.6mm small firing pin 300wm bolt, #27777.

If you can not send it back have LRI bush it.

 

[dfloomis]

If you have a small 1.6mm firing pin you need all 1.6mm small firing pin bolt bodies.

You can also buy a complete 2.0mm firing pin assembly to use with that new large firing pin 300wm bolt body you have, but that's $500+. I would send the large firing pin 300wm bolt back and exchange it for a 1.6mm small firing pin 300wm bolt, #27777.

Just confirming this part will work -

AI AX Replacement Firing Pin/Safety Assembly 6679​

And is there anyway to know as I try new calibers, which firing pin is best for each caliber?

 

[Kiba]

If you can not send it back have LRI bush it.

LRIs bushed bolts and modified firing pins are not compatible with the factory AI 1.6mm bolt bodies. I've had both. While the LRI turned down firing pin will fit in a factory AI 1.6mm bolt body a good portion of the LRI modified firing pin tip will be unsupported in a factory AI 1.6mm bolt and the firing pin tip will break after a bit of use.

Just confirming this part will work -

AI AX Replacement Firing Pin/Safety Assembly 6679​

And is there anyway to know as I try new calibers, which firing pin is best for each caliber?

Just get all 1.6mm firing pin bolts, that's the best option as you only need 1 firing pin assembly to share between all 3 bolts... Unfortunately they're not always in stock. 308 1.6mm RH bolt is # 27773.