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8/2/2026 6:16:05 PM EDT
Today I was trying IMI 77gr Razorcore in my rifle; I was getting popped primers towards the end of the strings of fire (around 15rds).  I have never had an issue like this before with this rifle.  In the same shooting session, shooting American Quality Ammunition 77gr I had no issues at all.  

Is this an ammo issue?
Is this a rifle overgassed issue?
Is it something else?

Details on the rifle:
- 14.5 Centurion barrel
- Surefire RC2
- BCM T3 buffer w/SpringCo Green spring
- Standard BCG
- Approx <5000rds fired

Things I have confirmed:
- Headspace g2g
- Firing Pin is in spec
- Inspected brass looks fine, dirty because of shooting suppressed


I have not had this issue with any other ammo I have shot in this rifle, including a different older lot of IMI Razorcore
8/2/2026 6:18:22 PM EDT
[#1]
Also to add, my buddy has fired this same lot of 77gr in multiple different rifles with no issues.  I have only tried it in this one.
8/2/2026 7:01:26 PM EDT
[#2]
This was an issue with some lots of the IMI razorcore.
It could be a combo of hot ammo, dirty/or tighter chamber than your buddies rifle.

I would do a deep clean and concentrate on the chamber area.
Sometimes after a while it can form a carbon ring that basically makes the chamber tighter. (I believe that's what happens)
I read about it a while ago so I could be off in my thinking.
8/2/2026 7:04:50 PM EDT
[#3]
Need more details on the barrel. How many rounds on it?

I had this issue a few years ago and thought it was the IMI but it turned out to be two bad barrels.
8/2/2026 8:00:07 PM EDT
[#4]
was it 100+ degrees in your part of TX like it was here?
8/2/2026 8:25:39 PM EDT
[#5]
Quote History
Originally Posted By Nobody69s:
This was an issue with some lots of the IMI razorcore.
It could be a combo of hot ammo, dirty/or tighter chamber than your buddies rifle.

I would do a deep clean and concentrate on the chamber area.
Sometimes after a while it can form a carbon ring that basically makes the chamber tighter. (I believe that's what happens)
I read about it a while ago so I could be off in my thinking.
View Quote


Yes, OP my question what type of chamber does that barrel have?
Wylde?

Also, if you google this, there are quite a few threads going back/forth over this problem.
8/2/2026 8:26:35 PM EDT
[#6]
Quote History
Originally Posted By Wake27:
Need more details on the barrel. How many rounds on it?  OP says, "  Approx <5000rds fired"

I had this issue a few years ago and thought it was the IMI but it turned out to be two bad barrels.
View Quote

8/2/2026 8:46:15 PM EDT
[#7]
Quote History
Originally Posted By mcantu:
was it 100+ degrees in your part of TX like it was here?
View Quote

This
8/2/2026 9:56:06 PM EDT
[#8]
Quote History
Originally Posted By TGH456E:


Yes, OP my question what type of chamber does that barrel have?
Wylde?

Also, if you google this, there are quite a few threads going back/forth over this problem.
View Quote


Barrel is 5.56 chamber with less than 5k rds on it.

Weather was nearing 100* today and we were in the sun all day.

I read some of the previous threads on it and want to chalk it up to ammo but want to do my own due diligence
8/4/2026 2:24:17 AM EDT
[#9]
IMI has produced a variety of 77gr that is loaded very hot, and some "not so hot" over the years. ( decades ? )

To me it sounds like given the heat and shooting suppressed, with a hot loading of the IMI .... well, you are seeing the results.

Any idea of how "old" your 77gr is ? ... IE , currently bought / produced , or some older stuff ?

And FWIW... IMI has made 5.56 ammo for various other manufacturers over the decades... specifically 55gr FMJ loads for Winc. ( hot ) and a 5.56 77gr load for Fed. ( also hot as heck )
*Hold on to your AR-15s. Their magic must be very powerful, or they wouldn’t want them.*
JAFOM.... Just another fat old man.

________________________________

TOGC,IADC

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