Bullet diameter - How big is too big? 30 BR

Since I'm trying to do things the best I can, I'll fire the cases three times and send them to Harrels and let them choose what matches best in their opinion. They have more experience than I do. If that doesn't work, then I'll adjust accordingly.

I had a blank LE Wilson bullet seater reamed with the same reamer as used for the barrel and it seems to work well.

As I said, I'm trying to do as much "Right" the first time around. I expect there will be some changes as I learn more.
I'd rather learn from others mistakes than my own, I'll make enough mistakes on my own.

I appreciate all of the input from everyone.
 
I'm with Al. Been fireforming with Bullseye and a wax or clay plug. The cases are straighter and no donut. I use a 223 barrel that I chambered 30BR to fireform.
 
IME "bullet diameter" and "bore diameter" are completely meaningless as regards safety or even velocity within normal parameters. The idea that a "tight bore" raises velocity is Urban Legend based on my testing and experience.

And I am a complete Safety Geek.

I remember when I was I Gunsmithing School a friend reamed a 6.5 Arisaka to accept 7.7 rounds and it didn't even really make any weird prressure as near as he could tell. Of course this was prior to Oehler and cheap chrono/pressure equipment. When he collected some bullets from a water tank they looked perty weird :)
 
BTW what I was trying to illustrate above is that IMO as long as you only do 5-10 rds at a time fireforming with pistol/shotgun powder does NO harm and promotes NO wear or firecracking.

IME


I'm interested to hear of others experience which may well differ. Right now I routinely fireform brass for weirdcats right in their own matchgrade barrels.

I can't state firmly enough just how important I find immediate cleaning to be though...... I basically now clean every 25-50rds, and normally immediately after firing the last group of the day altho when I leave a gun set up for days I've waited and cleaned next day but always I clean a warm bore.

I don't know why, don't even care to speculate but it works for me.

(Yes Frannie, that's Oxford Comma usage)


this day


tomorrow i might choose to not punctuate a'tall
 
alinwa said:
BTW what I was trying to illustrate above is that IMO as long as you only do 5-10 rds at a time fireforming with pistol/shotgun powder does NO harm and promotes NO wear or firecracking.

IME


I'm interested to hear of others experience which may well differ. Right now I routinely fireform brass for weirdcats right in their own matchgrade barrels.

I can't state firmly enough just how important I find immediate cleaning to be though...... I basically now clean every 25-50rds, and normally immediately after firing the last group of the day altho when I leave a gun set up for days I've waited and cleaned next day but always I clean a warm bore.

I don't know why, don't even care to speculate but it works for me.

(Yes Frannie, that's Oxford Comma usage)


this day


tomorrow i might choose to not punctuate a'tall
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1+
 
I haven’t got much to add since I do not make my 30 BR brass in a conventional manner.

But one thing did catch my eye. The size of those Lapua bullets. Where are you measuring?

The base might be a tad over .308, but I have never seen a Factory bullet measure that much over .308 on the actual shank.

I was under the impression that most bullets made in Europe were either right on size, or even a tenth or so under.

Have you checked your micrometers for standard?
 
jackie schmidt said:
I haven’t got much to add since I do not make my 30 BR brass in a conventional manner.

But one thing did catch my eye. The size of those Lapua bullets. Where are you measuring?

The base might be a tad over .308, but I have never seen a Factory bullet measure that much over .308 on the actual shank.

I was under the impression that most bullets made in Europe were either right on size, or even a tenth or so under.

Have you checked your micrometers for standard?
Click to expand...

My measurement is at the largest point of the bullet. Generally speaking, it's about 2/3 the way from the tip.

I believe the micrometers are reasonably accurate. I have several standards to check against and both (2) micrometers are Mitutoyo digital. The variation of all are within .00015 and that could very well be me.
 
brickeyee said:
Do not forget that the bullet obturates.
A fancy way of describing slugging up under rapid acceleration.
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Nahhh, 'slugging up' is just as fancy as 'obturates' and more job-specific...... truly lay terms will include "squishes like a grape", widens like a stepped-on kitten" or bulges like a dropped water balloon".....

notice I didn't mention fat women nor airborne pachyderms cuz RACIS'!!

I'm trying to achieve PC Nirvana
 
Assuming a standard accuracy freebore diameter of .3085 ish, as long as you can reach the rifling a .3089-.3090 shank bullet is a non issue. -Al
 
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I remember an article in PS about a 300 Whisper shot in a 223 rifle.

It all ends with a long sausage shaped bullet sticked along the barrel and fortunately nobody was hurt should I remember well.

So... the 30 bullet shank reached the 223 rifling ... even if conditions were not that ideal.
 
OliveOil said:
I remember an article in PS about a 300 Whisper shot in a 223 riflel.
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Such occurrences are more common that you might think. Many .300 Whisper loads will fit in a 5.56 mm chamber with little or no resistance felt by the shooter. Firing the mischambered Whisper usually destroys the upper, though the shooter is usually spared the worst of the possible injuries. (Normally, just an injured support hand.)
IIRC, the part not normally discussed is the strength of the 5.56 mm barrel in question - where the bullet lodged in the bore, the I.D. flared about .0001". Note that the upper receiver, bolt, bolt carrier, and barrel extension were all damaged (destroyed) by the overpressure. After new (undamaged) parts were used to rebiuld the upper, the rifle still shot acceptably well. (Damage to the lower receiver was limited to a bulged magazine well, and possibly needing new trigger parts and a safety lever.)

The same sort of damage noted above can occur in M-16 rifles when a squib round lodges a bullet in the bore, and a full powered round is fired immediately afterwards. BANG! BANG! Click! BOOOOM!

Video on the dangers of squib loads: https://www.youtube.com/watch?v=esfHFW-opGI
 
Asa Yam said:
Such occurrences are more common that you might think. Many .300 Whisper loads will fit in a 5.56 mm chamber with little or no resistance felt by the shooter. Firing the mischambered Whisper usually destroys the upper, though the shooter is usually spared the worst of the possible injuries. (Normally, just an injured support hand.)
IIRC, the part not normally discussed is the strength of the 5.56 mm barrel in question - where the bullet lodged in the bore, the I.D. flared about .0001". Note that the upper receiver, bolt, bolt carrier, and barrel extension were all damaged (destroyed) by the overpressure. After new (undamaged) parts were used to rebiuld the upper, the rifle still shot acceptably well. (Damage to the lower receiver was limited to a bulged magazine well, and possibly needing new trigger parts and a safety lever.)

The same sort of damage noted above can occur in M-16 rifles when a squib round lodges a bullet in the bore, and a full powered round is fired immediately afterwards. BANG! BANG! Click! BOOOOM!

Video on the dangers of squib loads: https://www.youtube.com/watch?v=esfHFW-opGI
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please show me where you see report of a gun blowing up from oversized bullets

https://www.youtube.com/watch?v=kpd4X8NNPIE
 
alinwa said:
please show me where you see report of a gun blowing up from oversized bullets
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Okay. Not a blowup, but not a bolt-actioned AR either.

https://www.youtube.com/watch?v=RbfIkaNlECo

BTW, the article in "PS" mentioned that the bullet that lodged in the barrel was a 150 grainer. The video showed the effects of shooting a 110 grainer in an AR. Damage is similar though.

Edited to add: NRA Article on firing .300 Blackout rounds through a 5.56 mm AR. Note the damaged upper photos.

https://www.nrablog.com/articles/2016/9/avoiding-the-300blk-ar15-kaboom/
 
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