IMI RazorCore 77gr. Popping Primers

[1911hombre]

Shot 40 rounds yesterday. Indoors because my outdoor range is a mudhole right now. 6 out of 40 popped primers. 14.5” stainless Noveske shooting suppressed with an RC2. Gun was freshly cleaned. Headspace is good. Factory gun that I’ve never had issues with. Anybody else have issues with this stuff?

 

[redneckbmxer24]

That stuff is on the spicy side so I wouldn't be the least bit surprised if some was spicy enough to pop primers. I've shot thousands of rounds of it (no recent lots) and flatter primers are the norm but I've never popped one.

 

[1911hombre]

Beyond the risk of a malfunction because of a primer ending up where it doesn’t belong, do you think I should just shoot it or what? I’ve got 360 rounds of this lot left.

 

[Rerun7]

Same. It’s very spicy but I haven’t had it pop primers yet. I’ve used it on several hog hunts to good effect.

 

[redneckbmxer24]

I wouldn't keep shooting it. It obviously over pressured and guns don't really like eating primers. I'd shoot it in something else though and see if it has the same issue. If it does I'd call up IMI and get it replaced. Might even be worth calling IMI now. If it's an issue with the lot they may already be aware of it.

 

[1911hombre]

I wouldn't keep shooting it. It obviously over pressured and guns don't really like eating primers. I'd shoot it in something else though and see if it has the same issue. If it does I'd call up IMI and get it replaced. Might even be worth calling IMI now. If it's an issue with the lot they may already be aware of it.

Sounds like a good plan.

 

[FredHammer]

Beyond the risk of a malfunction because of a primer ending up where it doesn’t belong, do you think I should just shoot it or what? I’ve got 360 rounds of this lot left.

Maybe on colder days and for training purposes. Not for when it really matters. Either that lot is spicier than the regular spicey IMI, your chamber is a bit smaller, or both. I specifically load my bullet hose hog shooting guns to the point just under primer popping, then back off a little to accommodate high heat days. I use fire & forget brass for this, since most get banged up from ejection and donated to the canyon mesquites. I've had primers fall into the FCG and really like to stay away from that. Lol

 

[tucaz]

has to be a tight chamber on noveske's part. i've been shooting razor core from 4-5 barrels for a long time and never had an issue.

 

[1911hombre]

So, I contacted my ammo supplier who will remain unnamed. He says 77 gr. IMI is famous for this when shooting suppressed. Says it was never designed for shooting suppressed. Says it's loaded on the ragged edge and any little issue can/will cause this. He sounds like he knows what he's talking about; claims he's seen this hundreds of times over the last ten years. Says it'll probably shoot fine unsuppressed. I've always had good luck with the Hornady Black 75 gr. BTHP. Maybe I'll veer back to that.

 

[jpjulian]

Change your firing pin. It may have been gas-cut on the tip when you popped the primers.

 

[redneckbmxer24]

So, I contacted my ammo supplier who will remain unnamed. He says 77 gr. IMI is famous for this when shooting suppressed. Says it was never designed for shooting suppressed. Says it's loaded on the ragged edge and any little issue can/will cause this. He sounds like he knows what he's talking about; claims he's seen this hundreds of times over the last ten years. Says it'll probably shoot fine unsuppressed. I've always had good luck with the Hornady Black 75 gr. BTHP. Maybe I'll veer back to that.

At least 75% of the IMI 77gr I’ve shot has been suppressed and I’ve never pierced a primer with it.

 

[1911hombre]

At least 75% of the IMI 77gr I’ve shot has been suppressed and I’ve never pierced a primer with it.

I hear you. Just to be clear, my primers are gone as in missing entirely.

 

[tucaz]

At least 75% of the IMI 77gr I’ve shot has been suppressed and I’ve never pierced a primer with it.

agreed. some of my 77gr shooting was suppressed too with no issues.

that supplier is FOS. even high end barrel makers have a tight chamber once in awhile. had a couple criterion barrels that were that way…223 and 308.

 

[Riverlife87]

spicy

 

[Gasgun]

I’ve shot hundreds of rounds of this stuff out of a MARS-L with a 14.5” mid gas barrel, 100% suppressed with a SureFire RC and never had a popped primer.

 

[bfoosh006]

What date is the headstamp ? Some of the batches were "spicy"

I have also shot a ton of it ( no suppressor ) over 15ish years.. no popped primers from various brand barrels and chambers.

Can a suppressor add enough pressure to pop primers ?

 

[sheepdog697]

I shoot this suppressed out of a factory JP from time to time, and as others have said... no popped primers.

 

[BurtG]

Shot a couple hundred through a 20” AR with 338 ultra can in summer with zero issues

 

[Rudy Gonsior]

I’ve seen quite a few guys run IMI 77gr. for SPR classes over the years. It definitely tends to be hot. Most guns eat it up fine but it’s also been an issue on occasion with several guns, popping primers and what not.

 

[Naaman]

So, what do we mean by "spicy"? I would have thought that the round was loaded to a higher chamber pressure (via more powder or a "hotter" powder or whatever), but when we compare to Black Hills 262, I see that the muzzle velocity is a smidge slower and the muzzle energy just a hair weaker on IMI than on BH.

So is 262 "spicier" than IMI Razor Core?

Or am I just not knowledgeable enough to interpret what I'm looking at here (<---I'm leaning toward this being the most likely possibility).

Seems logical that MV and ME correlate to chamber pressure, but I know enough to know that there could be (way) more to the story.

 

[bfoosh006]

FWIW... I had a 2013 lot of IMI 77gr that chrono'd at 2810fps ( 10shot average ) from a 20" CHF , and 2726fps from a 16" V-Seven barrel.

I would consider that "spicy"

CBC 2012 and 2014 77gr ran...... 2729fps and 2712fps from the same 20" 5.56 chamber, and 2620fps , 2640fps from the same 16"

And, in case you didn't know... IMI has produced various 5.56 loads for various manufacturers and sold under that companies name.
Winc. , Fed come to mind .
Fed. sold IMI 55gr under the Independence brand name that was also "spicy" has heck. ( Same 20" and 16" barrels..
FC 2,1, 13 headstamp..... 16" Av. 3195, ES 50.....20" Av. 3343, ES 94
Popped primers abound was the norm.
IMI 55gr 5.56 from the next year ( 2014 ) produced .Av 3158.....ES 69...............Av 3180....ES 38

Fed. also produced ( briefly ) a "FC262" load... it was also a "spicy" load.... from my 20" it popped 3 crimped primers from the first 5rds out of the box.

 

[Cynical]

I hear you. Just to be clear, my primers are gone as in missing entirely.

Where’d they go?

I wouldn’t shoot it because it’s only a matter of time before one makes it into the gas key and that’s a pain in the balls to fix.

 

[tucaz]

some of my IMI razor core velocities as measured with a magnetospeed…max velocities:

18” ballistic advantage 2770
18” douglass, 2900!!!
18” LWRC M6A3 DMR, 2680.
8000 rounds on that barrel so a bit worn out?
16” LWRC IC A5 2700
16” FN chromie , 2720

 

[Hoody2shoes]

It's not imi but my 12.5 criterion with the explorr on it gets around 2650 from the muzzle with bh 77's. No signs of over pressure in the spent casings.

 

[1911hombre]

So, I made it up to the range today. Same gun, freshly cleaned. Noveske Ares with a 14.5" stainless barrel with their Match Mod 0 chamber. Clamped the bayonet on my RC2 and ten shots were as follows: MIN-2671, MAX-2714, AVG 2693, SD-16.7, ES-43. One primer was proud by a few thousandths.
Then I shot a 10-shot string of a different lot number and it produced MIN-2617, MAX-2676, AVG-2637, SD-18.1, ES-59. So 56 fps slower than the first lot on average. The brass was cleaner and had less heavy swipes on it than the hotter lot. So I guess maybe the extra pressure is just over the line for this particular set-up. Another thing with the suppressor on I get very little variance on ejection pattern with a wide range of springs and buffers. Standard carbine spring and H buffer is about 2:00. Working all the way up in steps to a Sprinco Orange spring and an H3 buffer gets me about 2:30. I guess I'll have to buy a wrench for the URX-II barrel nut so I cn put an AGB on it. On another note, Black Hills is in stock everywhere and only about $100 a case more than IMI.....I got two cases coming.

 

[232593]

Maybe on colder days and for training purposes. Not for when it really matters. Either that lot is spicier than the regular spicey IMI, your chamber is a bit smaller, or both. I specifically load my bullet hose hog shooting guns to the point just under primer popping, then back off a little to accommodate high heat days. I use fire & forget brass for this, since most get banged up from ejection and donated to the canyon mesquites. I've had primers fall into the FCG and really like to stay away from that. Lol

I’ve seen similar with the 77 grain Razor Core. Cool days it’s generally fine out of my older Stag Varminter w/24” barrel. When it gets to 100-109 the primers are flattened out and there are ejector swipes all over the brass. No primer piercing or popping out yet. It chronos at about 2970 with a shitty ES at high temps.

Which is kind of odd considering with the same gun the Hornady 5.56 with the 73 grain ELD chronographed at 3053 with an ES less than 20 FPS and that brass looked fine despite the high temps.

 

[Rudy Gonsior]

I’ve seen similar with the 77 grain Razor Core. Cool days it’s generally fine out of my older Stag Varminter w/24” barrel. When it gets to 100-109 the primers are flattened out and there are ejector swipes all over the brass. No primer piercing or popping out yet. It chronos at about 2970 with a shitty ES at high temps.

Which is kind of odd considering with the same gun the Hornady 5.56 with the 73 grain ELD chronographed at 3053 with an ES less than 20 FPS and that brass looked fine despite the high temps.

Not odd at all, you’re dealing with two different powders, each of which have different pressure profiles. Nevermind projectiles weights and shapes, case geometry, etc.

It would be a mistake to assume an sort of linear correlation between muzzle velocity and pressure.

 

[FredHammer]

Not odd at all, you’re dealing with two different powders, each of which have different pressure profiles. Nevermind projectiles weights and shapes, case geometry, etc.

It would be a mistake to assume an sort of linear correlation between muzzle velocity and pressure.

Yup, gotta keep the peak, and in some cases, port pressures in mind!