pashiner Wrote:case neck dimensions are critically important. I learned this 2 years ago by blowing up a 300 blackout. I had worked up a good subsonic load with a cast lead bullet, and started forming brass from .223 range pickups. My load (7.2 gn Lil Gun) was just hot enough to cycle the action smoothly (pistol length gas, 16" barrel, std buffer and spring) but a case with a slightly thick neck snuck it's way into my magazine. It chambered, fired, extracted and ejected ok...but tore the lugs out of my barrel extension. left me a cute little 300blk belted magnum case in the brass catcher as a souvenir.
"if it seats, it yeets" is bad advice...even with those little pipsqueak loads!
Pashiner,
Your Blackout situation is interesting, but might not be related to bullet release.
Can I ask, how do you know it was an overly-thick neck that prevented the bullet from being released?
What thickness is your Blackout brass at the neck? For example, unfired Grendel Lapua is 0.0135" at the mouth (relatively thick). Gemtech 300BO brass is 0.01" at the mouth (about as thin as it gets).
A Grendel SAAMI chamber is reamed to .300" inside diameter (ID) at the neck. A typical cartridge will be about 0.290" outside diameter (OD). That allows 0.01" of space around the neck for bullet release - plenty of space. The other issue is not having too much space around the cartridge so it doesn't split on firing.
Not all Grendel chambers will be reamed to exactly 0.300". My Lilja neck is tighter. Spent cases measure 0.2925" OD at the neck. Fired cases will have sprung back slightly so the chamber will be maybe 0.2935". Still, plenty of space for shot release. As long as your loaded cartridge is not the same dimension or wider than your chamber then you are good to go for bullet release.
In this table due to slight differences in bullet diameters you get slightly different amounts of space around the neck when in battery; note the column 'OD Loaded'. With all the subtle variation from manufacturers there is still plenty of space for all bullets to be released.
[ATTACH=CONFIG]19150[/ATTACH]
FYI, 6.5Creedmore has a slightly tighter chamber mouth than Grendel at 0.2960". SAAMI specifies no more than 0.295" OD for loaded Creedmore ammo. That is 0.001" space for safe shot release - or in other words, 0.0005" between the cartridge and the chamber wall.
I have a tighter-than-SAAMI 6.5x47 match barrel with a 0.286" mouth. It requires all cases to be neck-turned so loaded ammo is no more than 0.2842" OD. I cannot use factory ammo in that barrel without kaboom. After all that, it is no more accurate than my other normal barrels.
Stone,
You can get an idea of the mouth dimension of your Odin chamber by measuring the OD of spent cases. Then measure the OD of those loaded unfired rounds in the photo. Check the difference for shot release and eliminate that as a reason for kaboom.
Note: Be careful of dings on the mouth from the spent cases hitting the receiver on the way out. the cases need to be perfectly round to get a good measurement.