Well, it doesn't appear to be the chrono... - Page 3

Well, it doesn't appear to be the chrono...

This is a discussion on Well, it doesn't appear to be the chrono... within the General Firearm Discussion forums, part of the Related Topics category; Originally Posted by Tangle Is this 5.56/.223??? The reason I ask, I've never seen COAL lengths less than 2.250" for 5.56/.223. That' includes Hornady, Western ...

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  1. #31
    VIP Member Array OldVet's Avatar
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    Quote Originally Posted by Tangle View Post
    Is this 5.56/.223???

    The reason I ask, I've never seen COAL lengths less than 2.250" for 5.56/.223. That' includes Hornady, Western Powders (TAC & Accurate 2530), Hodgdon, Sierra, Barnes, Berger, Alliant, and Nosler reloading manuals.
    No, they're for my 6mm Mongoose. The ASC magazine length limit is 2.30, the Magpul limit more toward 2.260, but I'm finding cartridge ogive engagement limits are less than 2.30 COL with some bullets, longer with some.

    The 85-grain HPBTs I loaded will engage the rifling at a COL of 2.200, whereas the 65-grain bullets will engage at 2.230". The 70-grain Nosler varmint bullets will engage the lands at a whopping 2.345".

    Currently I am limiting max COL to .010 less then ogive engagement length, though my current loads are a bit shorter until I can work closer to the COL max. The leade on the Mongoose seems on the shorter side, consider the longer bullets available. My bullet weight "goal" is best loads in the 65-85 grain range. The heavier bullets will be worked out at a later date . . . maybe. If long-range targets or hunting were a priority consideration, then the heavier bullets would make more sense.

    There is no published "data" on Mongoose loads other than what is on the forum where shooters have posted. That's one of the reasons I'm being a bit cautious. Some are using QuickLOAD to develop their loads.

    Supposedly, the Mongoose case has about 1-1.5 grains more volume than the 6x45mm case--a .223 simply necked up to 6mm--but I am working my loads up based on published 6x45 data (Hodgdon's with current powders). With some powders, BL-C(2) specifically, I cannot get the 6x45 max loads into the Mongoose cases. The higher 85-grain loads I made have pushed the limits of BL-C(2) I can get into the cases for that bullet.
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  2. #32
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    Quote Originally Posted by OldVet View Post
    No, they're for my 6mm Mongoose. The ASC magazine length limit is 2.30, the Magpul limit more toward 2.260, but I'm finding cartridge ogive engagement limits are less than 2.30 COL with some bullets, longer with some.

    The 85-grain HPBTs I loaded will engage the rifling at a COL of 2.200, whereas the 65-grain bullets will engage at 2.230". The 70-grain Nosler varmint bullets will engage the lands at a whopping 2.345".

    Currently I am limiting max COL to .010 less then ogive engagement length, though my current loads are a bit shorter until I can work closer to the COL max. The leade on the Mongoose seems on the shorter side, consider the longer bullets available. My bullet weight "goal" is best loads in the 65-85 grain range. The heavier bullets will be worked out at a later date . . . maybe. If long-range targets or hunting were a priority consideration, then the heavier bullets would make more sense.

    There is no published "data" on Mongoose loads other than what is on the forum where shooters have posted. That's one of the reasons I'm being a bit cautious. Some are using QuickLOAD to develop their loads.

    Supposedly, the Mongoose case has about 1-1.5 grains more volume than the 6x45mm case--a .223 simply necked up to 6mm--but I am working my loads up based on published 6x45 data (Hodgdon's with current powders). With some powders, BL-C(2) specifically, I cannot get the 6x45 max loads into the Mongoose cases. The higher 85-grain loads I made have pushed the limits of BL-C(2) I can get into the cases for that bullet.
    Thanks for clearing that up. And, you've hit on another suspicion I've been forced to look at. Can the high numbers I'm consistently seeing be due to the caliber?

    I don't see much reloading numbers in 5.56/223, probably because most that reload and measure velocities are loading a long range or precision caliber, such as 6 mm and 6.5 mm, etc.

    My buddy, commonly gets SDs under 10 with his 6 mms. When he loaded some 223/5.56 rounds for me, his numbers weren't significantly better, if better at all, than mine.

    I did pick up some H335 powder this morning - maybe it's a magic powder - I could use some of that!
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  3. #33
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    Quote Originally Posted by Tangle View Post
    Thanks for clearing that up. And, you've hit on another suspicion I've been forced to look at. Can the high numbers I'm consistently seeing be due to the caliber?

    I don't see much reloading numbers in 5.56/223, probably because most that reload and measure velocities are loading a long range or precision caliber, such as 6 mm and 6.5 mm, etc.

    My buddy, commonly gets SDs under 10 with his 6 mms. When he loaded some 223/5.56 rounds for me, his numbers weren't significantly better, if better at all, than mine.

    I did pick up some H335 powder this morning - maybe it's a magic powder - I could use some of that!
    I can't say much on .223s ballistics being inherently erratic. I've never chrono graphed any of my .223 loads, but now that I have one, I'll certainly run a few through my 788 and see what happens. My current loads are with IMR-4198, which was very erratic in my Mongoose fireforming loads, but I don't know if that was the powder or possibly the low volume loads I used.

    H335 seems to be a bit hotter and cleaner burning than BL-C2, if a powder can be called "clean." Certainly not as dirty. One of the Mongoose data posters mentioned "Benchmark for accuracy, H335 for speed." I don't know if that will apply to the .223. Another mentioned if only one powder could be used in the Mongoose, it would be H335, which is why I bought it to begin with. Time will tell if it is really the "Go-To" powder. It meters very well.

    So far, other than the experiment with marginal-performing 4198, I've stuck with Hodgdon powders for the simple reasons the 6x45 data is available and Bass Pro carries a wide assortment at a decent price. They also have Alliant powders, but I haven't tried them yet.
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  5. #34
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    The dimensions of the 223 case, kinda long and skinny, do promote the higher SDs than one will see when compared to a cartridge which is relatively short and fat. The 223 Rem isn't noted for being a benchrest cartridge due to this. I get better SD's from my 22-250 than from my 223s. The 6 & 6.5 mm cartridges excel in this arena, the 6mm Creedmoor and 6mm Lapua are excellent choices for precision work.
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  6. #35
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    Quote Originally Posted by CavemanBob View Post
    The dimensions of the 223 case, kinda long and skinny, do promote the higher SDs than one will see when compared to a cartridge which is relatively short and fat. The 223 Rem isn't noted for being a benchrest cartridge due to this. I get better SD's from my 22-250 than from my 223s. The 6 & 6.5 mm cartridges excel in this arena, the 6mm Creedmoor and 6mm Lapua are excellent choices for precision work.
    I'm not sure about that. The .222 Rem was the choice of bench shooters for quite a while, the case being no more/less than a shorter .223. Still any change to a case/caliber can alter results drastically. My theory might be the tiny bullets are more susceptible to ballistic variations than larger heavier bullets, but too many tack-driving .22 calibers shoot that down.

    The Mongoose case is based on the .223 case. The shoulder is bumped back some, the shoulder angle changed from 23 degrees to 40 degrees, the OAL shortened to 1.70 max, and then the case taper is reduced upon fireforming to increase capacity. That's the idea behind it anyhow.
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  7. #36
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    Good points, OV. The theory goes that increasing the shoulder angle improves uniformity of the powder burn by encouraging the powder to be burned in the case. Decreasing the taper of the case increases the volume thus having the effect of better volume/length ratio which also improves burn. The various 223 Improved cartridges have demonstrated this effect.
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  8. #37
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    Quote Originally Posted by CavemanBob View Post
    Good points, OV. The theory goes that increasing the shoulder angle improves uniformity of the powder burn by encouraging the powder to be burned in the case. Decreasing the taper of the case increases the volume thus having the effect of better volume/length ratio which also improves burn. The various 223 Improved cartridges have demonstrated this effect.
    Here's a photo of a .223 case converted to 6mm Mongoose on the left, and a somewhat battered .223 parent case on the right. You can see the shoulder is only slightly shorter but shoulder angle is clearly changed the taper is reduced. The neck is longer, even though it is trimmed during the conversion. The reduced taper makes fitting that last round into a magazine a bit tight, but in itself hasn't caused any issues.

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    I watched a YT video by some older gent who made big name barrels who said the reason .243 Wins ate barrels so quickly was because of the shoulder angle and small bore combo. I don't recall the guy's name, but he sounded like he knew what he was talking about.
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  9. #38
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    Few can compete with the 220 Swift for toasting barrels. I used to have one and barrel life was under a thousand rounds.
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  10. #39
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    Great stuff guys!

    After reloading and chronoing thousands of 5.56 rounds (higher pressure than .223) and trying everything I could come up with to reduce the velocity variations, I now can't help but think there's something inherent with the 5.56/.223 that just won't let it do any better. I use heavy bullets, 75 gr & 77 gr almost exclusively, but lighter bullets don't seem to make a difference and I have 1:8 twist barrels or better so the heavy bullets should stabilize fully.

    There may be something about the geometry etc. that causes velocity fluctuations. I don't know what it would be, but it's looking more and more like the numbers I'm getting are the fault of the caliber instead of something I'm doing or not doing.
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  11. #40
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    For gee whiz reasons, I loaded a few more rounds. 75-grain Speer Varmint HPs, 450 primers, H335 powder in FC cases.
    Hand weighed 25.1, 25.5, 26.0, 26.5, and 26.8 at a COL of 2.210. For comparison, I also set my dropper to 26.0 and drop-loaded 5 rounds to compare hand-weighed versus dropped loads. H335 is so dang consistent, I don't think it will make a difference, but we'll see.
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  12. #41
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    Man, @OldVet who would have ever thought you'd be hand weighing charges!
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  13. #42
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    Quote Originally Posted by Tangle View Post
    Man, @OldVet who would have ever thought you'd be hand weighing charges!
    I don't plan on making a habit of it, especially using ball powders. There is a certain randomness to shooting that I enjoy.
    Retired USAF E-8. Curmudgeon on the loose.
    Lighten up and enjoy life because:
    Paranoia strikes deep, into your life it will creep. It starts when you're always afraid... Buffalo Springfield - For What It's Worth

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