300 Fireball AR-15

What reamer are you guys using? Is is compatible with brass formed from thick bodied milsurp 5.56 cases?
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Not really. You'd have to inside ream or outside turn the necks to get them to fit. However Remington is making new 221 Fireball brass these days and it can be had through Wholesale Sports. The conversion from 221 to 300 is really easy.
 
kombayotch said:
Are you getting any step in neck thickness from the part of the neck that was previously shoulder material?
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If I understand your question correctly, yes - forming cases from 5.56/.223 means squeezing down the body of the case significantly. This means it will thicken somewhat, even if it didn't start "over-spec" for thickness in the beginning.

So, like Suputin said, inside reaming or outside turning is going to be necessary for proper chambering in a well-cut chamber like ATRS provides. The case will size to the proper neck OD, but then pushing that slug into the case will bump it back out of spec.

-M
 
Not what I was referring to... If you're using 221 Fireball, all that you're doing is necking up. There should be no significant cutting down like there is if you use 223. If you neck up, some parts that were previously in the shoulder area now become part of the neck. With certain calibers and makes of brass, it is noticeably thicker in that area and you get a step on the outside of the neck. After you fire, that step is on the inside of the neck, creating a nasty donut. A lot of guys who make their 260 Rem brass from Lapua 243 cases neck turn because of this.

Its shown here: http://demigodllc.com/articles/the-case-for-260-remington/?p=5
 
kombayotch said:
Not what I was referring to... If you're using 221 Fireball, all that you're doing is necking up. There should be no significant cutting down like there is if you use 223. If you neck up, some parts that were previously in the shoulder area now become part of the neck. With certain calibers and makes of brass, it is noticeably thicker in that area and you get a step on the outside of the neck. After you fire, that step is on the inside of the neck, creating a nasty donut. A lot of guys who make their 260 Rem brass from Lapua 243 cases neck turn because of this.

Its shown here: http://demigodllc.com/articles/the-case-for-260-remington/?p=5
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I get you now... yes, the dreaded 'donut.'

I don't see it being a huge issue with the .300 Fireball because you're not really adding appreciable neck length... however, I suppose a guy would have to look for that and correct it if necessary.

I know from what I've seen, most guys who go .221 to .300 don't ream or turn - but almost everyone who goes 5.56 to .300 reams or turns, depending on their setup. I'm planning on going 5.56 to .300 so I'm fully prepared for some serious neck turning in front of the TV watching the Stanley Cup playoffs...

-M
 
ben hunchak said:
I have been playing around with a 300 whisper bolt gun for quite awhile now and it is quite a challenge to get it shooting good, esp. with subsonic loads. With heavier loads you must be careful as pressures build quickly, my goals may be loftier then most as all loads tried were cast bullets of course. The rifle is a 700 action, trued, Gaillard barrel, Jewel BR trigger, Leupold 40X comp. scope.
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What barrel length are you running? Subsonic loads work best in short barrels because you're generally using a fast burning powder that gets used up in the first few inches of barrel. After that, its just friction and you have to lube the bullets to get consistent velocities. All of the guys down south are running with 16.5" barrels at most.
 
I have used subsonics in 18 - 20 inch barrels no problem. You do need to lube the bullets to ensure they don't stick in the bore when it gets dirty though. This is how I know that.

BulletStuckinBore.jpg


What I am discovering is that to get the AR action to cycle you need to use larger charges of slightly slower powders. That pretty much negates the possibility of sticking one in the bore.

These AR barrels that we are making are all in the 9-10" range. More for their compactness than anything else. However it does help with the subsonics.
 
18-20" is still too long for subsonics with a fast burning pistol powder. To get away from the lube, you need either a shorter barrel or a slower burning powder that will continue to push the bullet over a greater length of the barrel.

None of the guys down south are lubing their bullets in Whispers and they don't have any issues with the bullets getting stuck. And many of them are are running those whispers full auto. Boltgun guys aren't lubing either in 300, 338, or 510 Whisper rigs. They use a combination of a shorter barrel and powders on the slower side.

Its really no surprise that bullets are getting stuck in long barrels once they foul when a fast burning powder like Red Dot is used. The bullet is only being pushed for a fraction of its trip down the barrel and then all it sees is friction. That friction is increasing with each shot as the bore gets dirtier. But, the load was probably developed when the bore was clean and probably still had solvent/oil residue.
 
Hot. WAY hot.

I'm still loving and fondling the hell out of mine... I machined 10 grams off of the bolt carrier (already a semi - I swapped the FA BC it came with for the semi from my 5.56 upper, but kept the bolt since it's headspaced for that particular bolt) and now it's flawless with 180-grain subsonics. :)

Anyone looking for a SUPER-fun cartridge that doesn't blow up in your face like a shorty 5.56 does... yeah, this is an awesome choice.

-M
 
Any chance there are still dies available? Going to have to come in soon to see if you guys can get my ar build finished. How is your guys' work load looking over the next couple months?
 
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