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9/17/2020 5:59:48 PM
Posted: 10/4/2008 8:09:01 PM EDT
Fired my new 300 Whisper upper today. On the first round the magazine shattered and the bottom of the bolt carrier ripped off. The bolt locked right up in the barrel so bad that i had to go to some extreme measures to get the gun apart. So far it looks like the only damage was to the magazine, bolt, and bolt carrier. I ran a bore snake through the gun right before firing so I know there wasn't a bore obstruction and I'm assuming that since the bolt locked itself up in battery it must have been fully closed before firing. What caused this problem?

Link Posted: 10/4/2008 8:13:19 PM EDT
Reloads?
Link Posted: 10/4/2008 8:15:31 PM EDT
[Last Edit: 10/4/2008 8:29:01 PM EDT by KDavis]
Well first off... is it really a 300 Whisper chamber? And are you loading real 300 Whisper cartridges?

Are you mixing true 300 Whisper and 300/221? Do you know what the actual dimension of the chamber throat is?

Link Posted: 10/4/2008 8:29:18 PM EDT
Sounds like it was the load.
Link Posted: 10/4/2008 8:30:21 PM EDT
Link Posted: 10/5/2008 7:15:41 AM EDT
WOW!!!

Look at the spent case, it looks like a belted magnum! (and before someone posts, I know it's not)

I suspect reloader error. What was the load you were shooting? Were you sure of the chamber dimensions?

Glad you were not hurt.

Take care,
Bob S.

Link Posted: 10/5/2008 7:25:16 AM EDT
[Last Edit: 10/5/2008 7:28:14 AM EDT by SSN_Doc]
Looks like it wasn't fully in battery, and there wasn't enough chamber support at the edge of the case head.  Or improper headspacing issues that meant improper chamber suppport of the case.

This allows the weaker brass walls (thinner than the case head) to expand to the point of failure and eject hot gasses int the mag and action.  Improper lock-up would also account for the bolt beigh forced back into the carrier.

Another possibility is a complete failure of the bolt itself.  but this would mean simultaneous shearing of all the lugs at once, (not highly likely since the bolt was "locked up tight" in the barrel extension).
Link Posted: 10/5/2008 7:30:26 AM EDT
Possible slam fire? from too sensitive primers
Link Posted: 10/5/2008 8:51:19 AM EDT
The round fired was a reload. The barrel is a M1S 300 Fireball barrel. The brass was originally WWB 223 which was run through a Redding 300 Whisper Die and then trimmed back to 1.355, it would easily seat in the chamber and pop back out. It was primed with a Win small rifle primer and loaded with a 175gr bullet over 17.0gr of H110 to a total length of 2.170.

It was fired off of a gun vice using a string. With a new gun and a new load I didn't want my face anywhere near it.

The load is a pretty tame one that I woudnn't think would generate the pressures necessary to damage anything. What could I have done reloading to cause this? What would cause the "belted magnum" look of the fired shell?
Link Posted: 10/5/2008 9:31:11 AM EDT

Originally Posted By typer339:
The round fired was a reload. The barrel is a M1S 300 Fireball barrel. The brass was originally WWB 223 which was run through a Redding 300 Whisper Die and then trimmed back to 1.355, it would easily seat in the chamber and pop back out. It was primed with a Win small rifle primer and loaded with a 175gr bullet over 17.0gr of H110 to a total length of 2.170.

It was fired off of a gun vice using a string. With a new gun and a new load I didn't want my face anywhere near it.

The load is a pretty tame one that I woudnn't think would generate the pressures necessary to damage anything. What could I have done reloading to cause this? What would cause the "belted magnum" look of the fired shell?


Again the belted Mag look is from the posterior of th case not being fully seated in the chamber or properly supported where the brass is still weak.  The case head is solid brass, and I suspect, but do not know for sure, the true 300 whisper (or are we talking 300 fireball, I think I have seen both mentioned in this thread.) brass may have a deeper case head than .223 brass.  what ever the case may be, the brass was thin and not supported properly where it was allowed to expand and flow into the wider ring that you see now.

Was the upper properly checked for headspce?  Was the chamber finish reamed to the proper dimensions before assembly, or was the end user supposed to do the finish reaming, and get proper headspace?  Are 300 fireball and 300 Whisper that close to compatable to be messing with different dies, brass, and chamberings?  
It's a lot of variables to account for.
Link Posted: 10/5/2008 9:42:53 AM EDT
[Last Edit: 10/5/2008 9:44:30 AM EDT by SSN_Doc]
Did a little quick research and still m ay not know enough, but I see the Fireball and whisper are essentially the same cartridge based on .221 Remington Fireball brass.  I don't know if .223 brass is an adequate substitute though for the .221 brass.  But I see that the .221 is a shortended version of the .222.  It just gets better and better when you get into wildcat rounds.

Link Posted: 10/5/2008 9:54:18 AM EDT

Originally Posted By SSN_Doc:
Did a little quick research and still m ay not know enough, but I see the Fireball and whisper are essentially the same cartridge based on .221 Remington Fireball brass.  I don't know if .223 brass is an adequate substitute though for the .221 brass.  



Most guys use 223 brass as 221 cases are a bitch to get ahold of and tend to split when the neck is enlarged. If the bolt barely closes on a loaded round, could the headspace be that far off? These barrel have notoriously short chambers but the finish reaming is already done.

Would excessive pressure (double charge, wrong powder, bore obstruction) cause the case to look like that or would you say that it's probably a barrel problem?
Link Posted: 10/5/2008 10:03:00 AM EDT
Excessive pressure, or bore obstruction could cause similar problems  but I would suspect firing out of battery, or headspacing issues first.  If brass was not all properly trimmed it could cause headspacing issues as well.
Link Posted: 10/5/2008 11:24:44 AM EDT
[Last Edit: 10/5/2008 11:27:52 AM EDT by Stan_TheGunNut]
I would check the chamber to make sure it's the correct dimension.  I would also pull all the bullets you loaded, and check the brass to make sure it's the correct dimension.  Also check your powder charge.  175 grn is a small bullet for the whisper.  Most people I know use larger bullets, and prefer the 220's and the 240's.  

Once you have verified that your gun is okay to shoot and the chamber is the correct dimension, I'd get a new GI bolt and carrier (no need for the skeletonized one you had), and start over.  Reverify that your brass is sized correctly, and that the load is good.  You may want to get an experienced whisper shooter to take a look at your setup as well.

ETA:  I don't own a 300 whisper yet, but have a couple of friends who do.  I'll point them to this thread and I'm sure they can give you a better answer than I.
Link Posted: 10/5/2008 11:45:37 AM EDT

Originally Posted By typer339:
...... If the bolt barely closes on a loaded round, could the headspace be that far off? These barrel have notoriously short chambers but the finish reaming is already done.

Please define "barely closes on a loaded round"? Is it that tight that maybe it did not close all the way? You can get an idea by placing a peice of masking tape over the head and closing the bolt. I forget the deal, but I think on AKs you should be able to close it with 1 or 2 thickness' of tape on it, but not with 3? But definetly you should be able to close it with one layer of tape.

Originally Posted By typer339:
Would excessive pressure (double charge, wrong powder, bore obstruction) cause the case to look like that or would you say that it's probably a barrel problem?

Yes, I've had a .308 look just like that from a 1919 Browning, it was shitty Indian ammo that was famous for lack of QC and KBs.
Link Posted: 10/5/2008 11:57:34 AM EDT
Bad reload , over pressure round. Still enough pressure left over to blow out the case and carrier as round was extracted.
Link Posted: 10/5/2008 2:40:41 PM EDT
Link Posted: 10/5/2008 3:39:25 PM EDT
[Last Edit: 10/5/2008 3:41:42 PM EDT by KDavis]

Originally Posted By typer339:
It was primed with a Win small rifle primer and loaded with a 175gr bullet over 17.0gr of H110 to a total length of 2.170.



Ummmm... ya' might want to check that, I am pulling this from memory, but that sounds like a HOT load to me...
Link Posted: 10/5/2008 4:09:00 PM EDT
[Last Edit: 10/5/2008 4:10:07 PM EDT by MarineSniper8541]
Never....let me say this again....NEVER test fire a weapon with any type of reload.

A newly built rifle MUST be tested with factory ammo for its first few rounds to confirm that it can function properly.

This should also only be done after all head space and guaging has been completed and deemed within safety specs.

Judging by where the damage to the BC is, and IF the rifle did in fact have proper head space and guaging...it looks like it was the round. It looks like far too much pressure was exerted on the bolt carrier by the bolt. Also, that damage looks like it is right under the port leading down from the gas key. If that carrier, which is made of a harder, yet more brittle steel had not been in your rifle, and you had one made of mil-spec steel, you probably would have also lost your upper. Looks like everything was directed down and out of the hole created in the carrier. Lucky you.
Link Posted: 10/5/2008 4:21:03 PM EDT
I've been reading more about 300 fireball due to this thread; so all I have to do is swap my barrel and I can shoot this stuff? It works in AR 223 mags, drums? What sizing die to use to make 223 into 300?
Link Posted: 10/5/2008 4:54:29 PM EDT
[Last Edit: 10/5/2008 4:55:21 PM EDT by KDavis]

Originally Posted By Jimmy_Hoffa:
I've been reading more about 300 fireball due to this thread; so all I have to do is swap my barrel and I can shoot this stuff? It works in AR 223 mags, drums? What sizing die to use to make 223 into 300?

It is an interesting round... if you have a need for it, there is really only one other round* I can think of that is even in the same park. Some things to know before you jump in though:

It is not a "factory" round, you are pretty much going to end up reloading if you own one.

There are really two different things here, the 300 Whisper was developed by JD Jones, other people use a round that is *really, really* close to the 300 Whisper (300/223), but the neck dimensions and case thickness in the neck area are different -- you HAVE to know what your chamber is to get the most from this cartridge -- and know what your brass is made from, necked up 221FB or cut down 223/5.56mm.

It is kind of a fussy round when it comes to reloading...

You need to get a barrel... and you need to have the gun setup by some one that knows the cartridge, cutting the feed ramps and making things work -- plan on a short gas system and an adjustable manifold, this gives you the most versatility.

Mags are regular AR15 5.56mm mags... but most guys do a little work to the front of the mag, to get better feeding, it does not effect the mag and it works fine with 5.56 still.

*338 Specter -- Marty is the man behind this.
Link Posted: 10/5/2008 5:22:58 PM EDT
From the looks of the case, it is definitely an over pressure load.  Are you sure about the powder and amount you used?  It takes a lot of pressure to flow brass like that and I'm guessing it blew out at the extractor where it wasn't supported.  
Link Posted: 10/5/2008 5:52:08 PM EDT
H110 is a magnum pistol powder.  Are you sure it's recommended for the 300 Whisper or ANY AR round? 17 grains of H110 will pretty much fill a .357 magnum case so that might leave some air space in the 300 Whisper case that could cause erratic ignition.
I don't have any experience with the 300 Whisper but I have loaded several pounds of H110 in magnum pistol rounds, and it kicks ass.  I'm sorry to hear about your unfortunate event but thanks for sharing it with us.
Link Posted: 10/5/2008 6:17:14 PM EDT
[Last Edit: 10/5/2008 6:26:48 PM EDT by berk73]
looking on some reloading charts they have H110 for the 300 whisper at 10-14 grains powder,  17 isnt that far off but is definetly more than reccommended for that weight.  they do list using 17gr for 150gr bullets tho but NOT for 175 gr

sierra reloading book has 14.3 gr as a MAXIMUM for that bullet weight

hmmm, yeah I'd have to say 17grs is a hot, hot, load, anything else not quite right with the gun and its a force multiplier for disaster
Link Posted: 10/5/2008 7:30:06 PM EDT
[Last Edit: 10/5/2008 7:30:55 PM EDT by Messer]
17 gr. of H-110 is a "pretty tame" load if you are shooting 125 grain bullets, not 175 grain bullets. Where did you find the load data you were using?
Link Posted: 10/5/2008 8:19:36 PM EDT
I replaced the bolt carrier and bolt and tried again today using the gun vice and some very different loads (220gr over 8.9 and 9.1 of H110 and 240gr over 8.6 and 8.9 of the same) and got some very consistent velocities with MOA accuracy at 50 yards and no sign of any problems with the brass. I'm pretty happy with it right now.


I'd get a new GI bolt and carrier (no need for the skeletonized one you had), and start over.


The skeletonized bolt carrier came with the side charging upper that was on the gun, I'd much rather have screwed up a milspec BC. I'm just happy the upper came out OK.


I would pull down any rounds from that batch you loaded just to be safe.


Already Done.


Never....let me say this again....NEVER test fire a weapon with any type of reload.

A newly built rifle MUST be tested with factory ammo for its first few rounds to confirm that it can function properly.


I agree with this 100%. The problem is that there are no saami specs for this round so the only manufacturer (Corbon) may not actually be safe to shoot in my gun.


17 gr. of H-110 is a "pretty tame" load if you are shooting 125 grain bullets, not 175 grain bullets. Where did you find the load data you were using?


I found the load on quarterbore's website (listed as 168 over 17.2 of H110). I was also loading some loads with 335 powder earlier. I started using an RCBS Chargemaster and am starting to think that I didn't get the 335 completely cleared out of it prior to starting the H110 loads. Stupid hurts, but in this case I only lost a $190 bolt carrier. I've paid more for lessons.

Thanks for the responses guys.
Link Posted: 10/6/2008 5:52:33 AM EDT
Take a look at this thread...

quarterbore link

It seems M1S barrels might have a short throat...

You might want to think about having a chamber cast done.

Good luck,
Bob S.
Link Posted: 10/6/2008 6:37:49 AM EDT

Originally Posted By typer339:
I replaced the bolt carrier and bolt and tried again today using the gun vice and some very different loads (220gr over 8.9 and 9.1 of H110 and 240gr over 8.6 and 8.9 of the same) and got some very consistent velocities with MOA accuracy at 50 yards and no sign of any problems with the brass. I'm pretty happy with it right now.


I'd get a new GI bolt and carrier (no need for the skeletonized one you had), and start over.


The skeletonized bolt carrier came with the side charging upper that was on the gun, I'd much rather have screwed up a milspec BC. I'm just happy the upper came out OK.


I would pull down any rounds from that batch you loaded just to be safe.


Already Done.


Never....let me say this again....NEVER test fire a weapon with any type of reload.

A newly built rifle MUST be tested with factory ammo for its first few rounds to confirm that it can function properly.


I agree with this 100%. The problem is that there are no saami specs for this round so the only manufacturer (Corbon) may not actually be safe to shoot in my gun.


17 gr. of H-110 is a "pretty tame" load if you are shooting 125 grain bullets, not 175 grain bullets. Where did you find the load data you were using?


I found the load on quarterbore's website (listed as 168 over 17.2 of H110). I was also loading some loads with 335 powder earlier. I started using an RCBS Chargemaster and am starting to think that I didn't get the 335 completely cleared out of it prior to starting the H110 loads. Stupid hurts, but in this case I only lost a $190 bolt carrier. I've paid more for lessons.

Thanks for the responses guys.


That's definitely a pretty stout load.  I use 20 grns of H110 with my Hornady 300 grn XTP in my .44 magnum lever/ built Ruger wheel gun, just for reference sake (large pistol primer).
Link Posted: 10/17/2008 8:15:11 PM EDT
[Last Edit: 10/17/2008 8:27:34 PM EDT by pomofo]
That was definitely a hot load.  Sierra lists 14.3 with 175-180 grains, and Hornady lists 14.5 grains.  Did you seat the bullet into a dummy round and see how it loaded?  I got my M1S upper today and loaded up some dummy rounds.  240 SMKs had to be seated to 2.120" before they would seat without jamming in the rifling.  That's a VERY short throat.  

ETA:  I remember looking at Quarterbore's site and noticing that all of his loads are much hotter than what are in the manuals.  On a lot of loads he also doesn't mention whether he's using an AR or a bolt gun.  Loads that might be safe in a Remington 700 wouldn't be safe in an AR.
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