How compressed is too compressed?

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Augenblick
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How compressed is too compressed?

Post by Augenblick »

So I was trying to use up some cfe BLK and some cast coated bullets 217gr Hoosier. Trying to seat them to 2.06" (mfg recommendation and what feeds and passes case gauge) COAL I got rings from the seating stem on the bullet with 12.5 grains. Only able to seat to about 2.083".

Turned out that the brass "X-treme 300 BLK" head stamps and they weighed about 13 grains more than LC brass. I surmised that this resulted in less case volume and the seating ring is due to compressed load.

They passed case/headspace gauge. So my question is, is it safe to shoot? I have a Sig Rattler 5.5"and a 16" AR in 300 blk either one safer?

Thanks.
Kdablackout
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Re: How compressed is too compressed?

Post by Kdablackout »

I have run into the same issue as you have. My converted 223-300aac has more case capacity then the X-treme brass, I do run some very lightly compressed loads in my converted ones but I do not want to heavily compress as much as the x-treme brass would take so I have set them aside to use if I get a faster burning powder.
Maybe others will with more knowledge will chime in to give a good guideline for how much you can compress.
I do check to see case capacity. weigh shell fill, with water and weigh again and subtract the difference. Do this for a few of each head-stamps to compare.
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dellet
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Re: How compressed is too compressed?

Post by dellet »

Too much compression causes a few different problem.

Deform the bullet, poor accuracy.

Deform the case and it may not chamber.

Change the ignition quality of the primer, may cause a pressure spike.

Slow powders generally don’t usually have a problem with compression changing the pressure curve, fast powders are generally the opposite.

CFE BLK is pretty safe to compress, if you can. It is such a fine powder that if you drop it right, it’s impossible to compress. That’s where the bullet damage comes from, easier to bend the bullet than compress the powder.

Seating the bullet slow helps. Think about filling a can with fine sand and trying to push your finger into the sand. A slow steady push will get you there. Try to punch it in and you’ll break your finger.

CFE and heavy bullets, basically you find the length you can load the bullet to, figure out how much powder will fit under that bullet at that length, and there’s you max load.
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Augenblick
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Re: How compressed is too compressed?

Post by Augenblick »

Thanks that was quite helpful.

When I reduced the powder charge the seating ring went away and I was able to seat at the desired depth so I think I had the problem correctly identified as a compression issue.

I'm still unsure of how other loaders gauge compression. I have read some describe hearing the powder crunch. Others describe it by feel. I did notice when I was trying to seat the bullets with the compressed load that it was much harder and as Dellet said the bullets did deform a bit. I did not notice the loads "growing" in COAL post seating and I had only the lightest of crimp.

The biggest problem I had was the very long, really irregular cast hitek coated bullets that I had to seat them so short for them to feed/chamber. This combined with a new brass headstamp "X-treme" which had less case volume than the Lake City I had been using and the fact that cfe BLK doesn't compress much (well documented by Dellet as I have since read).

The reason I was trying to get more powder in with such a big/long bullet was to get more velocity because the barrel on the rattler is ridiculously short. Probably will have to do this with a faster powder.

I will pay more attention to case volume in the future.

I did find a cast hi-tek 220gr bullet that I really like. Steel Valley Casting makes a really excellent boat tail, semi cannelure spire point. Really uniform, no key holing, minimal expansion needed for seating. I just need to find one the right powder.

I did take the compressed loads to the range and fired the lowest powder charge from behind steel with a welding glove on. The case/primer showed no pressure signs so I went on to fire the others continuing to check for pressure signs. As loud and dirty as cfe BLK is, it is quite forgiving.

I'm still reading and searching for the post where Dellet tells us the perfect powder for subs and supers but I just haven't found it yet.

Thanks for the replys.
30plinker
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Re: How compressed is too compressed?

Post by 30plinker »

Augenblick wrote: Fri Sep 30, 2022 11:32 am So I was trying to use up some cfe BLK and some cast coated bullets 217gr Hoosier. Trying to seat them to 2.06" (mfg recommendation and what feeds and passes case gauge) COAL I got rings from the seating stem on the bullet with 12.5 grains. Only able to seat to about 2.083".

Turned out that the brass "X-treme 300 BLK" head stamps and they weighed about 13 grains more than LC brass. I surmised that this resulted in less case volume and the seating ring is due to compressed load.

They passed case/headspace gauge. So my question is, is it safe to shoot? I have a Sig Rattler 5.5"and a 16" AR in 300 blk either one safer?

Thanks.
13gr difference in brass weight is screaming "something wrong", possibly. That is almost a whole gram. What kind of case capacity (grains of water, weight case empty, then fill and re-weigh) do you get?
Augenblick
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Re: How compressed is too compressed?

Post by Augenblick »

On the way to work this am I pulled the two head stamps randomly from the bucket LC 87.4gr, X-Treme 100.6 gr. The X-Treme case "looks" thicker walled. I'll clean it up and measure volume and get back to you.
Augenblick
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Re: How compressed is too compressed?

Post by Augenblick »

So I picked up one each at random of the LC and X-Treme brass. 87.5 and 101.6 gr respectively. The unsized lengths were 1.465" and 1.540". To a just visible miniscus 1.6cc and 1.5cc. 24.5 and 23.6 gr of water. So even though the X-treme case was slightly longer it held less water by volume and weight.

I measured again after FL resizing. LC and X-treme respectively. 87.5 and 101.6 gr, 1.349" and 1.362", 1.55 and 1.45 cc volume, 24.1 and 22.7 gr water weight.

I am confidant that the X-treme case is heavier, thicker walled and less volume than the LC brass. This explains why I was unable to seat the same bullet with the same powder charge to the same depth in the two cases.

I still don't have a good idea of how to tell how compressed a load is and I welcome any feedback on that.

I was a bit surprised that my case length grew so much after firing and got shorter after resizing because I thought that resizing made the neck grow. My brass came from factory new brass so I never measured it beyond the sheridan ammunition gauge after resizing. I use the Mighty Armory 300 BLK resizing die (easily my favorite die) Can FL resizing set case length back?

I have read alot about FL vs neck resizing and I think the FL resizing makes sense for me reloading for AR pattern platforms. I realize that FL sizing can affect case longevity. I like the easy go/no go of the Sheridan gauge and I have no problems feeding/chambering/ejecting and LRBHO.

I'm really new to the whole reloading thing and I really appreciate this group and everyone's feedback. I feel like starting with 300 BLK is the deep end of the reloading pool.
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dellet
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Re: How compressed is too compressed?

Post by dellet »

Augenblick wrote: Fri Oct 07, 2022 4:08 pm So I picked up one each at random of the LC and X-Treme brass. 87.5 and 101.6 gr respectively. The unsized lengths were 1.465" and 1.540". To a just visible miniscus 1.6cc and 1.5cc. 24.5 and 23.6 gr of water. So even though the X-treme case was slightly longer it held less water by volume and weight.

I measured again after FL resizing. LC and X-treme respectively. 87.5 and 101.6 gr, 1.349" and 1.362", 1.55 and 1.45 cc volume, 24.1 and 22.7 gr water weight.

I am confidant that the X-treme case is heavier, thicker walled and less volume than the LC brass. This explains why I was unable to seat the same bullet with the same powder charge to the same depth in the two cases.

I still don't have a good idea of how to tell how compressed a load is and I welcome any feedback on that.

I was a bit surprised that my case length grew so much after firing and got shorter after resizing because I thought that resizing made the neck grow. My brass came from factory new brass so I never measured it beyond the sheridan ammunition gauge after resizing. I use the Mighty Armory 300 BLK resizing die (easily my favorite die) Can FL resizing set case length back?

I have read alot about FL vs neck resizing and I think the FL resizing makes sense for me reloading for AR pattern platforms. I realize that FL sizing can affect case longevity. I like the easy go/no go of the Sheridan gauge and I have no problems feeding/chambering/ejecting and LRBHO.

I'm really new to the whole reloading thing and I really appreciate this group and everyone's feedback. I feel like starting with 300 BLK is the deep end of the reloading pool.
I think you need to remeasure any fired cases you might have around. If they truly measured 1.465 and 1.540”, then you need to throw the barrel in the garbage can. There is no way for a case to stretch that far in a good chamber.

In theory nothing wrong with the brass with lower volume, but you won’t want to use the same load in both cases. At higher pressure loads you’ll get in trouble, or accuracy will likely suck.

If you can post a photo of fired brass, next to unfired, it would be interesting to see.
300 Blackout, not just for sub-sonics.
Augenblick
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Re: How compressed is too compressed?

Post by Augenblick »

I found one piece of the X-Treme brass in my range bag that I had not yet processed and remeasured 1.3555". I made those measurements after a 14 hour day at work which is why you don't reload tired distracted or otherwise impaired. My calipers also display the numbers to the left and right of the decimal place in a full screen size and the other three in half screen X. Xxxx. I must have dropped the . 3 off when I recorded the measurements.

I feel a bit dumb but also relieved as it did not make sense. I am still confident that the X-treme brass is on average 13 gr heavier and has less capacity than the LC brass I had from before.

As always in reloading answers bring more questions. This has lead my to look more closely at my brass and not rely so much on my Sheridan ammo gauge. I did find that my LC brass (sold as "new brass" from stryker-cheap) measured as short as 1.336" which is out of spec but seems to function ok. I'm wondering since it is so short if it was converted brass.

Is 1.336" too short and if so what problems might I expect with that?

While I'm rambling - how do you guys keep track of the number of times you have reloaded your brass? I have read alot on this but really haven't found a consensus. Inspect all my brass before and after cleaning and de-priming and then case gauge after sizing and priming. Is it sufficient to just do this? I ask because it seems limiting and cumbersome to try and keep brass separated by times fired.

Thanks
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