Kaboom!


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Tuckerp229
December 28, 2008, 08:29 PM
With my tail over my eyes I humbly submit this kaboom from my range trip today. I have been reloading now for about 6 years without mishap. Today I went with my .30 carbine and most recent reloads to test some new bullets from Reminton. My recipe was straight from the Speer manual #13 page 262. I was using 14 grains of IMR 4227 behind Remington's .30 carbine jacketed soft points 110 grain. OAL was 1.66 inches. This recipe has been very good to me using straight lead 110 grain bullets for 2 years. I just decided to make up the jacketed bullets for better accuracy and less fouling.
The first 4 shots were quite impressive...less than 1/2 inch at 25 yards open sights and about 1 inch at 50 yards. The fifth shot toward the 100 yard range went Kaboom! I was uninjured by the grace of God but my carbine lost some wood out of the stock on the right side all along the action. No metal shows any sign of fatigue or cracks. The bullet case remained in the chamber with the entire bottom end blown away. The brass looks much like the typical HP bullet after expansion. Also the mag bottom blew off and all the rounds in the mag were forced out of the mag. Again no damage to the mag. I just reassembled it.
Other pertinent points: I use a Dillon XL650 with the over/under charge auto alarm. While it is possible...maybe probable that I double/ over charged the case I am none the less perplexed. The bullets are new to me and this recipe. I used a micrometer to verify the size and they run .303-.304 so seem OK. The 14 grains is dead in the middle of the Speer min/ max load.
It almost appears that the gun fired without the bolt being fully locked in place. This a WWII carbine so wear is possible.
Does anyone have any ideas as to the cause or does this seem like an obvious reloader error? I reason for probing the experience of you reloaders is to determine the real cause to avoid a repeat experience wherein I may not be so lucky.

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243winxb
December 28, 2008, 08:44 PM
they run .303-.304 Are you talking bullet diameter? .308" is the norm?

243winxb
December 28, 2008, 08:51 PM
hodgdon site list IMR 4227 max at 14.5gr compressed. for a 110 gr Hornady JRN. Could be the brass was tired, reloaded many time. Is the back of the case supported when in the chamber? That might have something to do with kaboom also.

Tuckerp229
December 28, 2008, 08:58 PM
Are you talking bullet diameter? .308" is the norm?

Yes I am talking bullet diam. I just checked the diam. from the bullet package and they are at .307. The other .303/.304 was from measuring the bullets that were actually seated in place in the case, ie, unfired rounds.

243winxb hodgdon site list IMR 4227 max at 14.5gr compressed. for a 110 gr Hornady JRN. Could be the brass was tired, reloaded many time. Is the back of the case supported when in the chamber? That might have something to do with kaboom also.

The case seems to be fully supported. As to the case age or number of reloads if any I don't know.

Thanks for the ideas.

NCsmitty
December 28, 2008, 08:59 PM
Do you have or can you show pictures of the failure?

NCsmitty

R.W.Dale
December 28, 2008, 09:01 PM
The bullets are new to me and this recipe. I used a micrometer to verify the size and they run .303-.304 so seem OK. The 14 grains is dead in the middle of the Speer min/ max load.


I suspect an extreme case of bullet setback based on this tidbit

243winxb
December 28, 2008, 09:13 PM
.303/.304 was from measuring the bullets that were actually seated in place in the case, ie, unfired rounds.
Looks like you might have found your problem, undersize bullet diameter. Are you crimping ? Make of dies? Bullet setback as said above?

flying
December 28, 2008, 09:19 PM
I would also be curious enough if I were you to pull another round from that box of loads. Take it apart & check powder quantity.
I know you said you had the powder check but *#*@ happens :)

Tuckerp229
December 28, 2008, 09:31 PM
"hodgdon site list IMR 4227 max at 14.5gr compressed. for a 110 gr Hornady JRN. Could be the brass was tired, reloaded many time. Is the back of the case supported when in the chamber? That might have something to do with kaboom also."

I cannot explain the difference between the Hodgdons and Speer specs. As for the brass I am not certain the number of times it was reloaded if at all. The back of the case appears to be fully supported.

"I suspect an extreme case of bullet setback based on this tidbit"

Which tidbit the 14 grains or the .303/4 diam?

"Looks like you might have found your problem, undersize bullet diameter. Are you crimping ? Make of dies? Bullet setback as said above?"

Wouldn't undersized bullet diam. allow the bullet free passage through the barrel? By the way I measured the bullets still in the Remington bag and they are .307 diam.
Dies are new RCBS carbides. As for bullet set back, I have never measured the gun against the bullets new or reloads. The Speer book listed 1.675 as OAL and mine were at 1.667. If this .008 shortness can cause a Kaboom I sure would like to know the mechanics of the concept.

How about headspacing given that the gun is from WWII? Also does anyone knoe if the .30 carbine will fire if the rotary bolt is not locked in place?

R.W.Dale
December 28, 2008, 09:37 PM
Wouldn't undersized bullet diam. allow the bullet free passage through the barrel? By the way I measured the bullets still in the Remington bag and they are .307 diam.

much more pressingly, a significantly undersized bullet such as the ones you mention would allow a free passage back into the case if it snagged on it's way into the chamber.

I'm confused however what bullets were .303/4" in diameter

Tuckerp229
December 28, 2008, 09:37 PM
Well I just answered one of my questions. I pulled out my other .30 carbine and discovered that it WILL fire before the rotary bolt is locked! This unfortunately is a new variable. I have never checked the bolt on my semiauto rifles after firing. Sure if something goes wrong like a stove pipe or jamb open I look and clear but this thing has never skipped a beat. I have not shot in winter with it before and this is Minnesota cold up here. Well I think a trip to a gunsmith is in order to check the gun for damage and spec's before I shoot it again.
Not to mention I get to dismantle a 100 reloads.....just in case.

Tuckerp229
December 28, 2008, 09:42 PM
"much more pressingly, a significantly undersized bullet such as the ones you mention would allow a free passage back into the case if it snagged on it's way into the chamber.

I'm confused however what bullets were .303/4" in diameter"

OK i get it, your theory is that the bullet being undersized was pushed back into the case maybe by the semi-auto loading action?

Sorry about the measurement confusion. I first mic'ed the finished bullets just where they entered the case. After I posted this measurement I pulled some uninstalled bullets from the Remington bag and measured back near the base area which would be recessed into the case if loaded. This bearing area near the base turned out to be .307 in diam.

243winxb
December 28, 2008, 09:48 PM
The Rem bullets are listed as .307" &.308" depending on what site you look. The bullet gets set back(pushed back into the case) when it hits the feed ram because its undersize (.303") The set back causes pressure to rise. But with the undersize bullet, i am not sure that would be a problem??:confused: You need to find out what you are doing to the bullet when loading to make them smaller in diameter. (tidbit .304" dia.) Your OAL seems ok, but my 30 carbine is long gone sold, so not sure:confused: How about headspacing given that the gun is from WWII? Also does anyone knoe if the .30 carbine will fire if the rotary bolt is not locked in place? I dont know:confused: The disconnector should be checked by a gun smith.

243winxb
December 28, 2008, 09:52 PM
NOT THE BULLETS THEN This bearing area near the base turned out to be .307 in diam. Have a gun smith check it out.

zxcvbob
December 28, 2008, 09:54 PM
Did you trim the cases after resizing? (I'll guess not if you loaded on a Dillon) Sounds to me like it fired out-of-battery. The case may have been too long and prevented the bolt from locking.

(I don't have a carbine, but I do load this cartridge for a revolver and I've seen the brass do weird things)

1858rem
December 28, 2008, 10:01 PM
another problem with the setback theory is it was a compressed charge

hodgdon site list IMR 4227 max at 14.5gr compressed. for a 110 gr Hornady JRN

ReloaderFred
December 28, 2008, 10:29 PM
Something that no one has addressed is the fact that for two years this rifle had been shot with lead bullets. This was the first venture with jacketed bullets after two years of shooting cast bullets.

It sounds to me like an out of battery discharge. This could have been caused by chamber fouling, or lead buildup at the leade (transition area between the chamber and rifling).

I'm not concerned at all about the original measurement of .304" diameter, since he said he had measured LOADED bullets, which means the measurement was taken on the ogive, not the shank. When bullets from the bulk bag were measured, they were of the correct diameter, so this is a non issue in this case.

I also don't believe bullet setback is an issue, since most loads in the .30 Carbine are compressed loads, as I believe this one is.

What has occured could be what is commonly known as a SLAMFIRE. He didn't say if he had pulled the trigger or it went off when cycled. If the trigger wasn't pulled, then it slamfired. If the trigger was pulled, it shot out of battery.

A close inspection of the brass, chamber and action is in order. If the brass is too long, then it could have held the bolt open slightly. My experience is that .30 Carbine brass grows with each and every firing, and needs to be trimmed regularly, which is a royal pain with those short cases.

If the chamber is severely fouled, then that could have held the round back enough that the bolt didn't fully lock up. There may be metal scraping on the locking lugs. Also check the locking lugs on the bolt and make sure they aren't cracked or broken. I've seen this in Carbines before.

The sear needs to be checked to see if it's working properly. If the sear slipped, then the hammer would fall prematurely, before the bolt had a chance to lock up. That's what the interrupter on the M2 Carbine does, delays the fall of the sear slightly.

Hope this helps.

Fred

Tuckerp229
December 28, 2008, 10:47 PM
"Did you trim the cases after resizing? (I'll guess not if you loaded on a Dillon) Sounds to me like it fired out-of-battery. The case may have been too long and prevented the bolt from locking."

Nope I didn't trim as the case lengths have all been under 1.280, most have been 1.278 or so. Max case length is 1.29. I just checked the remaining reloaded and unfired bullets and found the the case length is LONGER than the presized cases. They are turning up 1.283-1.287. I never would've thought that the cases would lengthen from sizing, belling and bullet insertion. Diam. of the unsized case runs about .35 and after sizing they run about .340-.342. I never considered that sizing...pushing the sides of the case in would/ could lengthen the case.

Still the fire out of battery theory has two variables:
1. reloader error, ie. case too long
2. M1 carbine quirk, I looked at my other M1 and discovered it WILL fire out of battery.

evan price
December 28, 2008, 11:00 PM
Yes, you need to check length after you resize. The brass you squish when you resize the case has to go somewhere. The cases will grow when resized, that is why they get weak as they get old, the brass thins out at each resizing.

zxcvbob
December 28, 2008, 11:01 PM
The cases are tapered. I've seen them actually get *shorter* sometimes when fired, then stretch when resized -- the brass has to flow somewhere.

.30 Carbine is one of the first cartridges I reloaded, and it really had me confused for a while until I learned to measure them after resizing. (belling doesn't matter.) They don't always have to be trimmed, but they always have to be measured and you can't predict which ones will be too long.

R.W.Dale
December 28, 2008, 11:01 PM
I never would've thought that the cases would lengthen from sizing, belling and bullet insertion.

Resizing is typically when case growth occurs,.

Tuckerp229
December 28, 2008, 11:15 PM
"Resizing is typically when case growth occurs,"


Until now I have only reloaded pistol calibers and the .30 carbine. I always thought the case stretching was a result of shooting the bullet.

lgbloader
December 29, 2008, 01:43 AM
I never would've thought that the cases would lengthen from sizing,

That is a scary thought, Mate. As others have advised, ALWAYS check case length AFTER sizing. Perhaps going back and reviewing the loading process in one of your manuals (Lyman book or ABC's Book) might be a good idea.

LGB

rcmodel
December 29, 2008, 01:40 PM
I have seen an instance with the .30 carbine in a Ruger Blackhawk where it would sometimes shear off a thin ring of brass from the case mouth and very tightly seize it in the end of the chamber against the headspace shoulder.

Then, the next round would not fully chamber until you dug the ring out with an over-size bore brush, and a lot of trying!

M-1 Carbines have an interrupted firing pin, in that there is a slot in the receiver, and a "tail" on the firing pin that doesn't line up until the bolt is nearly closed.

That is supposed to prevent firing pin bounce from firing a round before the bolt is fully locked.

However, it may not, if you are using soft or sensitive commercial primers.

It is also possible to make a primer even more sensitive by crushing it when you seat it.

In all, I agree that bullet set-back could not occur due to the compressed load.

I'd rather think it was a slam-fire due to a sensitive primer.

Or just an old over-worked case, that finally couldn't take it anymore!

rcmodel

presspuller
December 29, 2008, 02:25 PM
I too think it was an out of battery shot instead of a reloading issue.
For grins and giggles check for fouling to see if that could have constriced the throat enough to keep the round from seating all the way.
Since it seems the bolt was not shut when it fired I figure a smith will find no problems with the rifle other than what you reported.
Glad you was not hurt.

Tuckerp229
December 29, 2008, 08:22 PM
"That is a scary thought, Mate. As others have advised, ALWAYS check case length AFTER sizing. Perhaps going back and reviewing the loading process in one of your manuals (Lyman book or ABC's Book) might be a good idea."

My experience/ bias has been with handgun ammo. Furthermore I use a Dillon XL650 progressive reloader so the very idea of stopping after sizing to remove and check trim length seems to run counter to the concept of 300-500 rounds per hour. Yes I know kabooms destroy guns and injure people. I guess I have learned that rifle bullet reloading should be done on the single stage press. I am still a bit baffled as to why the straight walled .30 carbine is soooooo much different than say my .357 pistol rounds. These are high pressure, high velocity and yet I have had no trouble making up 300-500 per hour without case stretching issues. I have even read how members of college shooting teams make up huge quantities of .223 rounds and I don't remember that they stopped between the sizing and powder stage to check or trim. Go figure?

zxcvbob
December 29, 2008, 08:58 PM
I am still a bit baffled as to why the straight walled .30 carbine is soooooo much different than say my .357 pistol rounds. These are high pressure, high velocity and yet I have had no trouble making up 300-500 per hour without case stretching issues.

The main reason is because it's tapered. It also operates at higher pressure than .357. 9mm and .45ACP are also tapered, but they are a lot shorter (and fatter) than .30 Carbine so stretching isn't a problem.

I bought a .30 carbine shell plate for my LNL-AP progressive press, but I haven't figured out a good procedure yet. Probably run them thru twice: Once to resize, decap, and bell the cases. Then trim off-press. Then run the prepped cases again to prime, powder-drop, seat, and crimp.

Currently I just size and decap the cases with a Lee hand press while watching TV, then measure the lengths using my Ruger Blackhawk cylinder as a Go/NoGo gauge, and trim any that are too long. That way I have lots of prepped brass ready whenever I'm ready to reload .30 Carbines.

243winxb
December 29, 2008, 09:16 PM
My OLD RCBS dies have a special note on sizing the 30 carbine case. The .30m-1 carbine case is heavy-walled, tapered and must have some lubrication. We recommend lightly lubricating evry fourth or fith case for best results.Not lubricating will damage the shell holder. Thats part of the info. From another RCBS reloading die instructions The .30 M-1 carbine tungsten carbide sizer die is shipper from the factory for use with American commercial cases ONLY. The wall thickness of some military and foreign cases is to thick and should not be used with this die as damage to the die and shell holder could result The one instructions seem to recommend sizing a different way, but its unclear to me how the die should be adjusted for proper sizing as its different it seems from other calibers like 357mag types?:confused: Maybe a call to RCBS would help. Not sure that this has any thing to do with you Kaboom?:confused:

eagleseeker
December 30, 2008, 12:58 AM
I had the samething happen to me but i was shooting my 243 i had reloaded the brass three times on the fourth i had a kaboom i later after much searching i cleaned the inside of the brass an found stress cracks needless to say i no longer go past three reloads.

Grump
December 30, 2008, 05:55 PM
At the very beginning of my reloading experience, some .30 carbine cases with lead bullets had grown so long the crimped portion was over the "ledge" of the chamber and were "pinching" the bullets in the throat.

Very nice prints of chamber machining marks on the cases. A few were so high in pressure that the primer pockets no longer held a primer.

Checking case length after sizing is your friend.

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