9mm YHM barrel issue w/ Xtreme 147gr HP

[smdub]

Have a friend who is having trouble w/ a new YHM 9mm barrel in an AR.

147gr HP from Freedom Munitions are headspacing the bullet on the leade and not the end of the case. It bad enough that a round dropped in the chamber visibly sticks out too far. If he drops the bolt the bullet gets stuck. Pulling the charge lever pulled one round apart and required a rod to tap out the bullet. Other ammo feeds and shoots fine. I have not seen the gun yet but he came to me w/ the issue since I have similar AR9s (but not w/ YHM barrels.) Freedom uses the X-treme plated HP in these rounds:

https://www.xtremebullets.com/9mm-147-HP-p/xc9mm-147hp-b0500.htm

Anyone had trouble feeding the the Xtreme 147gr HPs? I have a bunch of other 147gr bullets but none of those to test. We're trying to figure out if the leade on the YHM barrel is short or the profile of the Xtreme HPs is too long. He says the HPs will drop into all his pistol chambers just fine. I have some 9mm barrels I chambered w/ a new Manson reamer that I want to test as I'm fairly sure that is SAAMI spec. Short of doing a chamber cast w/ cerrosafe Im not sure how to measure the leade of the YHM barrel. I could stick some split ball gauges down into it and do a rough comparison of the taper w/ other barrels? YHM says the headspacing is fine (which is likely is.)

 

[jimbobborg]

There's a big thread on Brian Enos' site about this. Most 9mm AR chambers are really too tight for anything except commercial 115gr ammunition. I started a thread on this a while back, asking about reaming 9mm barrels so I could load longer bullets.

Thread on BENOS: http://forums.brianenos.com/index.php?/topic/240958-throat-ream-9mm-pcc/

 

[smdub]

Good to know! Thank you. Will read that thread tonight. His YHM is melonited so we're not using my reamer to clean it up Could possibly center it in the lathe and run a toolpost grinder in there. But at that point likely simpler just to sell it and make/buy another. Though he is a hobby machinist like me and would likely take on the challenge just for the sake of doing it

FWIW, p27 is the 9mm Luger SAAMI spec (the web link has spaces in it so likely have to cut and paste to make it work)
saami.org/specifications_and_information/publications/download/Z299-3_ANSI-SAAMI _CFPandR.pdf

So which one is technically out of spec (or both?) The barrel or the ammo? Does a typical 147gr round touch the lands in a spec SAAMI chamber? Or is an AR barrel leade typically steeper than it should be? My curiosity is now getting the best of me. I'll check the angle of my manson reamer to see if its the 2deg (4deg included) spec. I have chambers I've cut w/ it to check bullet 'fit'. I'll try to measure some bullet profiles too.

 

[dbledoc]

If you want to see if they can chamber in mine. I will be happy to meet up with you.

 

[jimbobborg]

The barrels are a little short of spec, which is causing the problem. I have a stainless steel barrel, no fancy interior coating, so I'm getting that done, along with both of my CZs.

 

[outrider58]

Just ordered 500 of those Xtreme 9mm HP 147 gr. bullets to try in my ADCO ar barrel. It will be a couple weeks before I get a chance to load and test though.

 

[jimbobborg]

Just ordered 500 of those Xtreme 9mm HP 147 gr. bullets to try in my ADCO ar barrel. It will be a couple weeks before I get a chance to load and test though.

I'd bet good money you'll have the same problem. You'll have to load really short to get them to chamber without sticking in the barrel.

 

[outrider58]

I wonder what COAL he is loading to. I've seen COALs at 1.100 for XTP HP which seem pretty short. I've been loading PC bullets at around 1.270.