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Expecting a baby........300 BLK


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On 4/16/2022 at 11:10 AM, dpete said:

@BrianK   Yes thats a 200 grain Maker subsonic.  The only bullet I've used for Sub hunting.  I've also got 225 gr Hornady HPBT and 220 SMK for paper punching.  All three of them have almost the same point of impact at 50 yards with their respective loads.

These subsonic loads are what my 8" suppressed SBR likes. As always YMMV.
220 SMK in LC case.  9.7gr IMR 4227.  CCI 400 primer.  2.220 COAL
225 Hornady HPBT in LC case.  8.8 gr IMR 4227.  CCI 400 primer.  2.220 COAL
200 Maker HP in LC case.  8.4 gr IMR 4227.  CCI 400 primer.  2.120 COAL

All three of these loads are 970-980 fps which is the speed range this barrel likes. Yours will most likely like something else.
I tried using Lil'gun when I was first doing load development.  It worked just fine but I found that IMR 4227 was more accurate and much cooler burning.  My subsonic BLK magazines are standard 5.56 Pmags with the entire inner side rib filed out.
Rifle with mag.
mag in rifle
Top view of mag
By taking the ribs out completely these long fat basterds can be loaded to mag length instead of having to fit between the ribs.  They become dedicated sub mags by doing so because shorter supersonics would rattle around front to back in the mag not having the rib there to hold them.

I’m grateful to see this information, you just sparked an idea to give new life to two 30rd Pmags I previously modded to run 450 bushmaster back in 2013 before I traded off my 20” upper. 

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