seems odd

[redriverhunter]

hello all I was messing with some fired bass for 7mm 08. The brass was 308 sized with a Lee F/L die 7mm 08 die and has been fired 3 times. what I noticed is that an unsized brass will not accept a bullet, any other gun that I have; a fired piece of brass the bullet will fall into the case with no resistance.
The only thing I think it might be is I have heard is that sized down brass will have an increased neck thickness is there anything I should worry about.
thanks rrh

[Gofaaast]

Measure the diameter of the neck on a loaded round, and see if it fits the spec in your reloading manual. If you have the right accurate tools just measure the thickness of the brass at the necks in three places. If the thickest measurement is out of spec. the necks need turned.

[country gent]

If the case dosnt have room to release the bullet in the chamber it can raise pressure dramaticly. There is some natural spring back to brass so you may be on the raged edge. Measure the loaded neck dia of a factory cartridge ( or a reload in correct headstamped brass) and compare to your reformed loaded rounds neck dia. Another check is measure neck wall thickness on factory correct headstamp case and neck wall thickness on your reformed cases. Keep in mind on neck wall thickness .001 on a side thickness means .002 on dia due to being on each side of bullet. The added brass from .308 dia neck has to go somewhere when sizing down dia so necks become thicker. I have seen 243s formed from 308 that wouldnt chamber when loaded. You mau beed to neck ream or neck turn these cases to thin necks. Neck reaming can be done fairly easily, with little aditional equipment. Neck turning is a little more accurate as to concentricity and neck wall consistency but is more work and requires more equipment outlay.

[Wayne Smith]

Also check length. Cases can stretch and become slightly longer than the chamber. This can cause major pressure problems and will likely create a lip on the case that is smaller than the rest of the case, thus preventing the bullet from entering.

[Uncle R.]

Also check length. Cases can stretch and become slightly longer than the chamber. This can cause major pressure problems and will likely create a lip on the case that is smaller than the rest of the case, thus preventing the bullet from entering.

Yes.
Your OP didn't mention case length. If they were sized down and then reloaded three times they're almost certainly too long if they haven't been trimmed. Of course they can grow with repeated FL sizing too. Too-long cases can cause this problem, and of course thick case necks will cause this problem too.

Either way it IS a problem. If your fired cases won't accept a bullet you are at best on the very edge of a dangerous high pressure situation. Check the neck diameter of a loaded round of course, but even if it's within spec your chamber neck may be very tight. Check the length of the cases after sizing. Bottom line, if the fired cases won't accept a bullet something is wrong, something that could cause dangerously high pressure.

An old and wise gunsmith I once knew used to respond to all such queries by asking "Have you tried it with factory ammo?"
I'd suggest that would be a good next step in your investigation. If the fired factory cases won't accept a bullet it's likely you have a chamber problem. If they do accept a bullet, you have a reloaded ammunition problem.

Uncle R.

[Huffmanite]

FWIW, Have a Marlin X heavy barrel Varmit rifle in .308. Never a problem chambering any of my reloads in it. Then a fellow range member gives me a a nice Shilen heavy barrel, Savage threaded, with 300 rds down it. I install it on an action. Tried various pieces of .308 brass in it and no problem chambering them. First reload I tried would not chamber and got stuck in chamber. Tried one of these reloads in my Marlin.....chambered just fine. Hmmmmm. Tried several more of the reloads in the Shilen barrel rifle, all would not chamber, but would chamber in my Marlin.

Curious, seated bullets in maybe 5 different brands of 308 brass. Before doing this, I was able to chamber all five pieces in the Shilen barreled rifle with no problem. Only two of the five different brand's of brass with a bullet seated, would chamber in the Shilen barrel rifle. What was problem? Probably had a tighter chamber in the Shilen barrel than the Marlin barrel. But, neck thickness of different brands of brass was the reason.

[CHeatermk3]

OP said the brass was 308win sized down to 7-08.

Dollars to donuts the necks are too thick.

Either turn the necks down or get rid of them and get some of the proper brass for the rifle because you could be
(prolly ARE) gonna have a KABOOM on your hands.

[Bullfrog]

OP said the brass was 308win sized down to 7-08.

Dollars to donuts the necks are too thick.

Either turn the necks down or get rid of them and get some of the proper brass for the rifle because you could be
(prolly ARE) gonna have a KABOOM on your hands.

just bought some 7-08 dies and I wondered about reforming 308 down to 7mm. Now I am pretty set on just buying some 7--08 made brass to work from. Thank you.

[fatnhappy]

OP said the brass was 308win sized down to 7-08.

Dollars to donuts the necks are too thick.

Either turn the necks down or get rid of them and get some of the proper brass for the rifle because you could be
(prolly ARE) gonna have a KABOOM on your hands.


Without the benefit of measuring anything, I'd wager this post is correct. I'd also like to ask the OP if we're discussing bullets or boolits.

Sizing .308 to 7-08 leaves the cases shorter than factory 7-08. With only 3 firings I'd be surprised if they grew enough to warrant triming, unless the sizing die is out of whack and stretching the cases. In the last 20 years I've personally sized a couple thousand .308 cases to 7-08 for a pair of different rifles and not run into an instance of the necks being too thick with jacketed bullets. This includes military brass. That of course is my limited experience with a meager sampling of rifles and brass brands.

Boolits are a different animal and being as I use them sized .286" which fills the throat of my ruger perfectly, I can see how necked downed .308 brass with the additional .002" could cause problems, especially if the chamber is on the tight side.

On a parting note. Please stop what you're doing and start measuring. I would suggest you make a chamber cast or pound slug and use an accurate micrometer to determine your chamber dimensions EXACTLY.

For example: my loaded 7-08 rounds with hornady 139 flat based spitzers measure .3102" mean neck thickness with resized remington .308 brass. For the record the bullet measure .2841" so my brass is only .013" thick. You want a full thou of clearance. So were I to measure a chamber cast and determine my chamber's neck is less than .3112" in diameter then turning case necks would be warranted. Measuring a fired case isn't an exact representation of chamber dimensions due to it's elasticity BUT it a good stating point.

[warboar_21]

What I learned when I first bought my 6.5 Grendel and sized 7.62x39 down for it. First firing no problem. Second time I noticed swipe marks and flattened primers in several of the batch. I researched the issue and found out that brass would flow and thicken at the neck and create a donut. Inside neck reaming was the only thing that would remove it 100%. Neck turning wouldn't go down quite far enough on the Grendel brass to get rid of it. Not sure if it would or not on the 08.
What I did was buy a drill bit that was as close to. 264 and then chucked it in the cordless and got busy. No more issues after that.

[El Bango]

Try neck reaming then resizing again,problem should be fixed