I use the Lee full length sizing and seating die set, then their universal neck expander so the bullets seat well (I use my own 247gr lead bullets sized to .309). Then I use the factory crimp die to take the slight neck expansion off (This step is almost not necessary but I do it anyway.
New 300 blk
- Thread starter Todd S
- Start date
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I use the Lee full length sizing and seating die set, then their universal neck expander so the bullets seat well (I use my own 247gr lead bullets sized to .309). Then I use the factory crimp die to take the slight neck expansion off (This step is almost not necessary but I do it anyway.
Russ D
Ultimate Member
I did some preliminary testing yesterday. Neither of my loads were as accurate as Remington Factory UMC but they did function fine. Load one was
150gr Hornady FMJBT
16.5gr H110
LC 5.56, reformed to 300BLK
CCI primer
2.100"
Accuracy was OK, about 1" at 50 yards. It did not lock back on an empty mag. I'm running pistol gas and a Spikes T2 buffer.
Load two was
150 SMK's the rest being the same. Accuracy was a little better.
Next trip I'll switch to a standard carbine buffer.
150gr Hornady FMJBT
16.5gr H110
LC 5.56, reformed to 300BLK
CCI primer
2.100"
Accuracy was OK, about 1" at 50 yards. It did not lock back on an empty mag. I'm running pistol gas and a Spikes T2 buffer.
Load two was
150 SMK's the rest being the same. Accuracy was a little better.
Next trip I'll switch to a standard carbine buffer.
- Aug 17, 2011
- 26,177
Russ, I'm assuming your running a Noveske barrel?
If so, I believe you may want to bump to 17.0 - 17.2, that should get you to lock the bolt on an empty mag. I've gone as high as 17.8 on the 150gr FMJBT's, but that was hard on the brass. Accuracy was 2" or better at 105 yards.
Still playing with subsonic loads myself.
225gr Hornady Match BTHP
Formed LC brass
Wolf primer
8.8gr H110
2.258" COL - New Pmags, so I had to seat them a touch deeper to prevent feed issues.
Cycle fine, won't lock w/out suppressor. Accuracy testing at later date.
If so, I believe you may want to bump to 17.0 - 17.2, that should get you to lock the bolt on an empty mag. I've gone as high as 17.8 on the 150gr FMJBT's, but that was hard on the brass. Accuracy was 2" or better at 105 yards.
Still playing with subsonic loads myself.
225gr Hornady Match BTHP
Formed LC brass
Wolf primer
8.8gr H110
2.258" COL - New Pmags, so I had to seat them a touch deeper to prevent feed issues.
Cycle fine, won't lock w/out suppressor. Accuracy testing at later date.
Russ D
Ultimate Member
Nope not suppressed and yes 10.5". Still looking to buy a chrony so no velocity data yet.
warreng
Member
- Feb 1, 2012
- 25
Justler,
Thanks for the info. Would have replied sooner but I typically only have internet access at right now and they won't allow access to the site (go figure!)
Warren
Thanks for the info. Would have replied sooner but I typically only have internet access at right now and they won't allow access to the site (go figure!)
Warren
Russ D
Ultimate Member
- Aug 17, 2011
- 26,177
The 150 FMJBT Hornady's I've used have a cannelure, so I've been doing just a very light crimp - just for peace of mind.
2.065" COL, IIRC.
I'd have to go digging thru my load logs, but I think I even got them to reliably cycle at 16.8/16.9gr of H110. But let me double check before I say that for certain.
2.065" COL, IIRC.
I'd have to go digging thru my load logs, but I think I even got them to reliably cycle at 16.8/16.9gr of H110. But let me double check before I say that for certain.
- Aug 17, 2011
- 26,177
Yep, at that COL I was running 16.8/16.9gr H110 and had no issues. Ejector swipes were there, but not as prominent as the 17+gr loads.
Have an almost update on my 300. I built the lower from the Spikes group buy. I think some of my feed issues were not due to the ammo. The return spring that came with the stock kit was the wrong size. It was actually a longer spring than my other Spikes lower by almost two inches. 
I never thought to check the spring length. The bolt would lock but not all the back, like it is supposed to do. I ordered a new carbine spring from Joebobs. The lower now locks with the bolt all of the way back. Back to the drawing boards with my H110 loads. Now I can see if they will cycle correctly. I have no idea how or why they cycled at all the first time.
I never thought to check the spring length. The bolt would lock but not all the back, like it is supposed to do. I ordered a new carbine spring from Joebobs. The lower now locks with the bolt all of the way back. Back to the drawing boards with my H110 loads. Now I can see if they will cycle correctly. I have no idea how or why they cycled at all the first time.
wasntme
Active Member
- Jun 10, 2012
- 182
Have an almost update on my 300. I built the lower from the Spikes group buy. I think some of my feed issues were not due to the ammo. The return spring that came with the stock kit was the wrong size. It was actually a longer spring than my other Spikes lower by almost two inches.
You should have just cut some off....lol just dont cut off too much
Russ D
Ultimate Member
Just loaded up about 100 of the 150 Hornady 150 FMJ's. I started these loads at 17.0 grains of H110 and up to 17.5. I should get some pretty good accuracy testing results at the range tomorrow.
IndispensableDestiny
Ultimate Member
I picked up a RCBS set at Cabelas. I'd rather have the Redding set, but those are on long back order. I'm used to Redding dies.
I'm in the process of trimming to 1.365 my chopped and formed brass. I chopped to 1.390 - 1.400, which leaves a lot of material to trim. Too much. I used a mini chop saw.
I set up the seating die on my Rockchucker. Using Sierra 110 grain HP flat base, I get a COL of 1.950. I'm applying a very light crimp with the die.
The powder will be VV N110 because I have it.
I wanted to use Nosler 125 ballistic tips, but Cabelas had the Sierra's.
My gun is almost done. I just need the flash suppressor pinned and welded. Then install the barrel and rail on the upper. It's a Noveske 14.5 inch. The upper and lower receivers are Noveske that I had laying around since before the madness began.
Bravo757
Stand In The Gap
Hornady - might have to go custom shop order depending on inventory but worth it and then there's Redding - found a lot of not-so-concentric measurements from the other big name painted green but Redding has always been built spot on - again may have to go to there custom or semi custom ordering but either way that little extra money is worth it!
Last edited:
Russ D
Ultimate Member
I'm trimming to 1.350 before sizing. You can go as short as 1.348.
IndispensableDestiny
Ultimate Member
Are you trimming before forming, or are these already formed? The only reference I found for trim to length was 1.365 which is only .003 below the max length.
If before forming, what length do you get afterwards?
I plan on getting a Dillon 1200 trimmer and a .300 Blackout trim and size die. That will make things easier.
Russ D
Ultimate Member
Normally 1.352-1.353
IndispensableDestiny
Ultimate Member
Here's my first batch of brass. I made them from once fired Federal .223 brass. I made about 160.
Russ D
Ultimate Member
The FC is what I used the bulk of to make brass also. I just stuck a well lubed case in my Hornady die. I guess I'll be using the Lee's for a few weeks now until I get the Hornady back.
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