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  #11  
Old 07-07-2010, 01:51 PM
buffetdestroyer buffetdestroyer is offline
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Quote:
Originally Posted by Colohunter View Post
I'm assuming you are shooting the 110 gr VMAX supersonic, right? I would try to get a hold of some Accurate Arms 1680 for the subsonic loadings a number of people here, including myself have had better luck with 1680 cycling the subsonics.
With the 18.8 grains, that would have to be a supersonic load unless something is seriously wrong with his setup.

The question I have is which bullets have you tried for subsonic work? I noticed that the lighter bullets are more forgiving than the 220+grain matchkings. I believe this is because the amount of surface area of the bullet that comes in contact with the case neck and barrel requires considerably more energy to push the bullet out.

You might try something between 150 to 180 and work down to subsonic speed from a known 1200 fps load with whatever powder you choose. This way you will have reliable function despite the supersonic crack. Just keep on dropping the load until it is subsonic or it doesn't cycle the next round.

Depending on your barrel you may get great accuracy or poor accuracy with a functional load, but with sub loads 1.5 - 2 MOA for hunting within 200 yards should be adequate for most medium size game. I know many barrels (including mine) are capable of well under sub moa, but if reliability is the critical factor, I would sacrifice a little on accuracy since I am not shooting long distance where group size is more crucial. I also noticed when I get full cycling, it is louder than when it just ejects.

I was as frustrated as you were i8asquirrel because I built mine from parts and was worried that function issues were with the gun and not the ammo. That is the tricky thing about the 300 Whisper/Fireball is that the lack of commercial ammo makes it the shooter's responsibility to ensure proper function of the gun AND the ammo! I think it is typically an ammo issue more times than not that can solve the problem.

One last thing... the overall length is crucial for reliable function in an AR. I was initially seating the bullets out way too far for AR mags to work. When you seat them properly, you will be able to push the rear of the round and it will easily slide out of the magazine without getting hung up.
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Last edited by buffetdestroyer; 03-18-2011 at 10:36 PM.
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  #12  
Old 07-07-2010, 03:31 PM
i8asquirrel i8asquirrel is offline
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Yes 110 V max is supersonic.... But I have had no luck getting anything else to cycle..Supersonic or not I have only used bullets up to 200gr. because I have a 1x10 twist....I plan on using 190 SMK for subsonic loads and a 125/165 for hunting? My gas port is currently .106" but I plan on having my smith open it to .120"?
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  #13  
Old 07-07-2010, 04:32 PM
buffetdestroyer buffetdestroyer is offline
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Quote:
Originally Posted by i8asquirrel View Post
Yes 110 V max is supersonic.... But I have had no luck getting anything else to cycle..Supersonic or not I have only used bullets up to 200gr. because I have a 1x10 twist....I plan on using 190 SMK for subsonic loads and a 125/165 for hunting? My gas port is currently .106" but I plan on having my smith open it to .120"?
That could very well fix the problems you are having. The other issue may be that the gas block wasn't perfectly aligned with the port... but either way your gunsmith should be able to remedy that when putting it back together.

Did you swap to a lighter buffer like was suggested? Also, are you shooting suppressed when these FTF's happen? The back pressure of a suppressor should help supersonic loads be functional even with a smaller gas port.

I had similar reliability function issues when I converted a Saiga 12 with a 24" barrel that I cut to 18.5". The loss of pressure from the shorter barrel was too much so the action would barely function. I had to add a gas port (it came with 3) and then I had to open each of them up .05" before it would cycle reliably. Gas guns are finicky if not built right for the job they are doing and I hope that you get it resolved because I know how frustrated you can get! However once you solve the problem, you are wiser from the experience gained!

If you think it is still a load issue I found this posted on the web and I think it might help (moderator, please let me know if it is inappropriate to keep this link up - it's not mine).

http://listmequick.com/300/Sierra300whisper.pdf

Just keep in mind that their overall length is not appropriate for an AR so make sure it works in your mags.
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Last edited by buffetdestroyer; 03-18-2011 at 10:36 PM.
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  #14  
Old 07-07-2010, 04:50 PM
i8asquirrel i8asquirrel is offline
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Thank you for the link ,That is the load info I have been working with...I beleive the problem is gas port (at least thats what Im trying next) I am not discuraged the darn thing shoots very well ,just not feeding.....Suppoes I need to build a bolt gun in this calliber !!!! then feeding wont be an issue.
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  #15  
Old 07-07-2010, 05:07 PM
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Colohunter Colohunter is offline
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Here is a link for a thread discussing AA1680 for subsonics, including my load for a 150gr subsonic load. Might be worth trying some 1680 before you start drilling out the gas port.
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  #16  
Old 07-08-2010, 12:35 AM
i8asquirrel i8asquirrel is offline
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Ok I had the gas port drilled to .116" and put my rifle length buffer spring into my lower( I have a CAA adjustable butstock) and the weapon fired and functioned fine. I was shooting 296 powder under 190smk,160FTX by hornady, and speer 150hcft.....bolt still not locking back after last round but heading in the write direction!
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