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AR15.COM
12/27/2013 6:17:59 PM EDT
I was wondering if the "M" engraved on my bolt meant that it is MP/MPI? Is it HP tested and shot peened? Also is bolt made out of carpenter 158 steel. There's also an E on the left side of the carrier.  Everything else looks good. Thanks.
12/27/2013 7:17:44 PM EDT
[#1]
same question, just got the 20" hammer forged upper with BCG and CH, are the BCGs which come with the premium line (not PTAC) MPI?

Description doesn't mention they are MPI or HPT, but it seems like people are getting MPI'd BCGs.
12/29/2013 7:09:15 PM EDT
[#2]
Bump for an answer.
12/29/2013 7:30:12 PM EDT
[#3]
My PSA BCGs that are magnetic particle inspected say MPI on them, I've haven't heard of any bolts that are that just have an M.
12/29/2013 9:40:29 PM EDT
[#4]
Greetings everyone, first post here...

My dad ordered a Premium BCG from PSA about 10 months ago and it was also marked with single "M."  I seem to remember an old thread where it was determined that the "M" signified "MPI".  The Premium BCG I ordered during the Black Friday sale was marked "MPI/HPT".

It seems that this question goes back a ways

12/29/2013 11:21:19 PM EDT
[#5]
The BCG that came with my first upper was very nice.  Had MPI marked on the bolt.  Chromed lined carrier and key (very shiny).  Had to send the complete upper back due to incorrect machining of the upper receiver (off set).  The second upper came with this questionable BCG.
12/30/2013 12:05:06 AM EDT
[#6]
Quote History
Quoted:
Greetings everyone, first post here...

My dad ordered a Premium BCG from PSA about 10 months ago and it was also marked with single "M."  I seem to remember an old thread where it was determined that the "M" signified "MPI".  The Premium BCG I ordered during the Black Friday sale was marked "MPI/HPT".

It seems that this question goes back a ways

View Quote


How's your dad's "M" marked BCG holding up? I also wondered if the buffer tube is 7075 or 6061. Is everything premium or just certain parts.......it kinda sucks when you have to question what exactly what you're getting.
12/30/2013 4:36:18 AM EDT
[#7]
Quote History
Quoted:


How's your dad's "M" marked BCG holding up? I also wondered if the buffer tube is 7075 or 6061. Is everything premium or just certain parts.......it kinda sucks when you have to question what exactly what you're getting.
View Quote View All Quotes
View All Quotes
Quote History
Quoted:
Quoted:
Greetings everyone, first post here...

My dad ordered a Premium BCG from PSA about 10 months ago and it was also marked with single "M."  I seem to remember an old thread where it was determined that the "M" signified "MPI".  The Premium BCG I ordered during the Black Friday sale was marked "MPI/HPT".

It seems that this question goes back a ways



How's your dad's "M" marked BCG holding up? I also wondered if the buffer tube is 7075 or 6061. Is everything premium or just certain parts.......it kinda sucks when you have to question what exactly what you're getting.


The BCG looked good otherwise and no issues so far, but he doesn't get out to shoot that often. So it really hasn't been put through its paces.
12/30/2013 8:16:06 AM EDT
[#8]
Quote History
Quoted:
My PSA BCGs that are magnetic particle inspected say MPI on them, I've haven't heard of any bolts that are that just have an M.
View Quote


The generic M16 bolt carrier group PSA sells has an M on the bolt.

the PSA premium BCG has hpt/mpi markings on the bolt.

If the opening post got a premium BCG with just an M stamped on the bolt, sounds like he got the generic m16 bolt in the premium carrier.
12/30/2013 8:41:05 AM EDT
[#9]
Unless it's stated in the description, I always assume something is not (ie: HPT/MP, 7075 Extentsion).

Prior to Black Friday, I ordered two Premium M4 uppers. One with BCG and one without.  The one without, I ordered a BCG that specifically stated HPT/MP. The other one I wasn't concerned with.

Below is the description of the BCG that comes with the Premium M4 upper. No listing of HPT/MP. So I assume it's not. If it shows up with the bolt so marked, I got lucky.

Bolt Carrier Group: M16 Full Auto Profile Bolt Carrier Group with Carpenter 158 Steel. Gas key is secured with grade 8 fasteners and staked per mil-spec. Full-auto profile bolt carrier is manganese phosphate treated outside, and chrome lined inside.
View Quote
12/30/2013 1:27:44 PM EDT
[#10]
Quote History
Quoted:
Unless it's stated in the description, I always assume something is not (ie: HPT/MP, 7075 Extentsion).

Prior to Black Friday, I ordered two Premium M4 uppers. One with BCG and one without.  The one without, I ordered a BCG that specifically stated HPT/MP. The other one I wasn't concerned with.

Below is the description of the BCG that comes with the Premium M4 upper. No listing of HPT/MP. So I assume it's not. If it shows up with the bolt so marked, I got lucky.

View Quote View All Quotes
View All Quotes
Quote History
Quoted:
Unless it's stated in the description, I always assume something is not (ie: HPT/MP, 7075 Extentsion).

Prior to Black Friday, I ordered two Premium M4 uppers. One with BCG and one without.  The one without, I ordered a BCG that specifically stated HPT/MP. The other one I wasn't concerned with.

Below is the description of the BCG that comes with the Premium M4 upper. No listing of HPT/MP. So I assume it's not. If it shows up with the bolt so marked, I got lucky.

Bolt Carrier Group: M16 Full Auto Profile Bolt Carrier Group with Carpenter 158 Steel. Gas key is secured with grade 8 fasteners and staked per mil-spec. Full-auto profile bolt carrier is manganese phosphate treated outside, and chrome lined inside.


So far the only thing that makes it a premium is the barrel? Everything else seems to be just stardard run of the mill components. I guess for the price I can't really complain though. Plus their customer service has been good, atleast for me.
12/30/2013 5:24:10 PM EDT
[#11]
The 'M16' BCG PSA provides with some 'premium' uppers has a bolt marked M.



Their PREMIUM PSA marked BCG are HP and MPI marked.
12/31/2013 7:42:07 AM EDT
[#12]
Quote History
Quoted:
The 'M16' BCG PSA provides with some 'premium' uppers has a bolt marked M.

Their PREMIUM PSA marked BCG are HP and MPI marked.
View Quote


Correct.