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Discussion Starter · #1 · (Edited)
Started messing with reloading 300Hamr for my mini14 rebarreled to 300 blkout rechambered to 300Hamr T20 build. Anyone here reload for 300Hamr? [125-150 gr bullets.] Background, I rebarreled the original mini14 [as I already have a 300 blkout] and i needed a bbl shaped to M1 garand external dimension to work with a M1 stock and gas cylinder. I recently had ASI rechamber it to 300Hamr. Did that to give me a bigger case than the blkout to hold more powder to give me more gas to run the gun. It was running intermittently but with a very weak op rod spring setup and a case full of powder. Obviously with the bigger case I have more pressure as I backed out a primer in yesterday’s testing! Had to back off. Getting good ejection. I’m having to return to the magazine fitment as I believe that is an issue too with the differences in case dimensions. I swapped out my mag release with a polished up one last night. I’ve experimented with a dozen powders, cfeblack and LilGun being the most promising with the 300blkout. My current testing is with LilGun as that was in my measure.
 

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That's a new one on me!!! Looks like it's just a little less powerful than the 126-year-old 30-30 Winchester.

These new sub 30-30 Winchester class cartridges keep coming along like popcorn popping.

People seem to be having fun with them. Nice light recoil in a light and handy rifle.

That's why the Model 94 Winchester became the most popular rifle in history in the 30-30.

I continue to be amazed at how many similar cartridges are coming along every year.

How are you doing at finding reloading components?
 

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Discussion Starter · #3 ·
I had looked at the 7.62x40 as a upgrade from the blkout but then found the Wilson 300Hamr which was even bigger and still able to use 130-150 gr bullets. Bought a set of Lee dies and a cutoff jig for my HF saw. I mainly shoot cas with big lead .45 boolits which I can cast. Powder and bullets actually have been no problem over the 2 years, finding the occasional can here and there and I have plenty pre pandemic projectiles but there aren’t any reasonable primers. I’m using old cci sr primers from 2013 [newest brick is 2018], currently have 7 bricks. Have more of those than any other type. Might need to do some horse trading eventually.
 

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Well, we all hope availability will be improving soon.

I imagine some reloaders will be along soon, although it may take a while because of the relatively new cartridge.
 

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I like W296 for my blkout loads. Lil' Gun can get a little weird at higher temps.
I've actually had good results with CFEBLK in my .17 Hornet.
 

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Discussion Starter · #6 · (Edited)
Thanks Rover but Blackout loads for the AR do not generate enough gas to run my crazy build I’m afraid. I tried them.
I worked on my mag well last night and jbwelded a 3/16 inch piece of oak on the front of the opening to make it smaller which keeps the mag more vertical. Seems it was tipping up in the front which lowered the rear causing the bolt to override the rear of the next round. I’m not using the front magazine pin only the rear mag catch/ release. Also cleaned and lubed the op rod spring, it was dry. Just got my T20 to work with 26.0 gr LilGun 130 gr jsp [NOT FOR AN AR- THESE LOADS ARE FOR MY BUILD ONLY], ejected and fed the next rd fine. Still have room in the case too. Next I’ll try some different bullets to see what works.
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Just pointing out Lil' Gun is not the most stable of powders.
I would have to go through my notes but if I remember, Lil' Gun did fine but w296 and 1680 seemed a little more consistent.
Sounds like a fun build! Any pictures?
I haven't done any load development for 300 in a while since I have the performance I want out of the projectiles I use.
Been revisiting .17 Hornet and .22 Nosler.
 

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Discussion Starter · #8 ·
Never tried 1680. Might try to borrow some if anyone I know uses it. It’s slower than LilGun on a burn rate chart. I might retry CFEBLK and H110 again.
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