AR15 .300 Whisper / Blackout help

Hey guys,

Have got an AR15 that im trying to reload subsonic 240gr pills for with no luck cycling. Basically ive tried a bunch of powders , (4895 bm2 ,vv110) among others) but some will cycle but dont have enough speed (4-500 fps) and the powder is very compressed (f%ckn jammed) in. tried different seating lengths etc
The powder that everyone seems to be using is vitavouri 110, and which ive brought a shitload of, which fills up the case perfect (9.5 grains) and gives good velocity (1050fps) but it wont fully cycle the action.it kicks halfway. This seems to be the powder that i need to get it cycling.

So whats the answer? do i need to buy another gas block? can i tune my current one to cycle this powder? or do i need to stick to factory loaded 220 grainers?
rifle is a 12" barrel that dan hardy made with supressor etc. can upload a pic if that helps

This is my first ar so my knowledge is limited (read - zero) haha.


cheers guys

do the factory loads cycle OK? I would be keen to see a photo ...

yea factorys cycle sweet no problem a. yea cool ill try post one up

http://www.youtube.com/watch?v=mNU6X...ature=youtu.be

thats it cycling with 220grainers

What's the gas port diameter and what length?

The data I found had 11.2 grains of AA1680 16" barrel 1010 fps for 220smk subs

AA1680 seems to be right between 2205 & 2207 so they maybe worth a try.

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Originally Posted by Spanners

What's the gas port diameter and what length?

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do I just measure that up with the tape measure?

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Originally Posted by Kiwi Greg

The data I found had 11.2 grains of AA1680 16" barrel 1010 fps for 220smk subs

AA1680 seems to be right between 2205 & 2207 so they maybe worth a try.

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the 240s seem to suck up just that little bit extra room though aye, even seated right out. its a bastard haha. id realy like to get the vitavouri 110 powder working if i can seeings we got a whole lot of it hahaha. but failing that, more experimentation on powders.

Pistol, carbine, mid and rifle are the standard lengths
Measure it and google the lengths tosee what you have
Will prob be carbine

tried both and neither cycled

carbine length

I think a pistol length gas system is needed for subs

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Originally Posted by Beavis

I think a pistol length gas system is needed for subs

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what do you mean? it already cycles with factory subs, and other powders that dont give me adequete veloicty, just not with this particular powder that is reccomended and used elsewhere

Sorry didn't fully read the thread. Definitely sounds like the powder could be the issue. Not timing properly or what not. Mate had a similar problem in his SLR except it was the other way around, was ejecting like a crazy c*nt and it was the powder he was using. Try a lighter weight buffer.

A pistol length system (like mine) will cycle anything, however it is overgassed on hot supers
Need to build a 2 position dual adjustable block.

A light buffer will hammer the gun to bits when shooting supers

Where does it dump the super and sub brass as in 2 oclock or 5 oclock etc

I have my ideas as to why, and its nothign to do with the loads you're shooting - see it time and time again from the same source.
PM for more info

thats cool as, i want one for xmas santa, do you hear me santa !(def bugga)

I'd start with the simple stuff .............. Lube it well

Just noticed you said you were using Vitavouri 110, I think that's quite different to the Hogdons 110 that's recommended on the 300BLK site. The Hogdons 110 will do both super and sub-sonics with a carbine gas system.

Ray.

Sounds dumb, but are you putting a small dab of grease on the bolts wear surfaces (the 4x rails on the bolt and the hammer), this makes a big difference.

kj

IF 220gr bullets work , I would just be happy with that , from what i can recall , the 240gr bullets are much dearer than 200-220gr bullets , also depending on the twist of your barrel , the 240s may or may not stablise .

Later Chris

yea i hear ya bro. except i purchased heaps of 240s so i was trying to get them to work in it. wanted to see if the 240 being less stable, were more likely to tumble hard. not after benchrest accuracy as minute of fallow head or double tap to goat lungs is good enough under 100 yards, o well can still use them in the 300 rum if all else fails hahah. thanks bro will stick to 220s if all else fails.

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Originally Posted by ChrisF

IF 220gr bullets work , I would just be happy with that , from what i can recall , the 240gr bullets are much dearer than 200-220gr bullets , also depending on the twist of your barrel , the 240s may or may not stablise .

Later Chris

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In my 300BLK with 16" barrel I had to open up the gas port a little to get it to cycle subsonic. Dan Hardy wasn't sure what size hole would work with subsonic so set hole for supersonic, anyway our local gunsmith had a drill reamer the right size, now works for both. Also found Hodgdon LILIGUN to work really well in both sub and supersonic with a lot less pressure signs - 125gn Nosler at 2295fps and 110gn V-Max 2395fps. I liked the 225gnBTHP Hornady for subsonic, was accurate with a soft skin that worked well on goats. Great little round on goats, the supersonics are by far the best proformers.

hardy built your AR ? yea i was hoping to hook up with spanners next time hes back and do something similar, be intersted in some more details about opening up the gas port and reamers used for sure! thanks for the loads till will have to try the 225z

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Originally Posted by 300MAG

In my 300BLK with 16" barrel I had to open up the gas port a little to get it to cycle subsonic. Dan Hardy wasn't sure what size hole would work with subsonic so set hole for supersonic, anyway our local gunsmith had a drill reamer the right size, now works for both. Also found Hodgdon LILIGUN to work really well in both sub and supersonic with a lot less pressure signs - 125gn Nosler at 2295fps and 110gn V-Max 2395fps. I liked the 225gnBTHP Hornady for subsonic, was accurate with a soft skin that worked well on goats. Great little round on goats, the supersonics are by far the best proformers.

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hi dave
Im having exactly the same issue with 240smk using n110 from my dpms 16 inch barrel with carbine gas port. they go super sonic at 9.9grn and still wont cycle. The most reliable mix ive found so far is 9.1 grn lil gun, 240smk oal 2.250. the long oal is to maximize chamber psi. this load has been 90% reliable but on a cold day the odd round will crack.
My supers im running sierra 125 sp with 18gr n110 (full case!) oal 2.060 MOA pulling abt 2200ft. Using h110 19.9grn 2400ft 1/2 MOA, getting pretty hot. and lil gun 19 grn with 125 nosler bt 2350ft, MOA oal 2.10
hope this helps