Subsonic Build

[ChrisF]

Hi Guys ;

 

Just finished a Subsonic build , basically a Suppressed AW clone .

 

Badger M2008 action , using BT can made for AI .

 

[6.5shooter]

Is this in 308 cal?

Very interesting rifle!! Have you got to test it yet?

 

Regards

 

Garry

[Scotch_egg]

PLease stop teasing us with the M2008 you know they are impossible to get into the UK

[nemasis243]

What are you gonna use that for???

[ChrisF]

Actually , they are not impossible to get , just hard , you can buy them from Badger & export thru a FFL exporter in the US .

 

Any way , this has a trueflite 1-8 twist barrel , the AI original has a 1-9 twist .

 

Have not shoot it yet , will shot it soon , using trailboss powder , and yes its chambered for 308 Win , I think IF I used a shorter case say a 30BR or similar , then I would have feeding issues etc .

 

Cheers Chris

[Scotch_egg]

OK you got me all but impossible at a realistic price lol

 

The use of a B&T mod is a rarity in NZ, I will also ask what specific use is a subsonic .308?

[ChrisF]

These actions are alot less than Surgeon , and I see people in the UK using Surgeon actions in Builds etc .

 

So cheaper than Surgeon ( Surgeon are 200-300 dollars more expensive ).

 

What some one in the UK should be doing is building a even better clone of the AI AW action , than the Badger , instead of building limitless copies of the Rem700 type .

 

Cheers Chris

[ChrisF]

What use , any thing I want , I built it as a super FUN Toy , and if it does not work , its real easy to re-barrel to any other 308 class round .

 

As AI have used this can for quite a while , its probably good to go ( OK ) , my only difference is the twist , on mine is a 1-8 ,and AI uses a 1-9 twist .

 

Cheers Chris

[Finman]

I am a bit confused: where does the 'subsonic' fit? is this a .300Whisper or does it use downloaded .308Win to propel the bullets at subsonic speeds? Or does the 'subsonic' epithet refer to the fact that this is a quiet rifle? Any help welcome...

 

Finman

[ChrisF]

I intend to use this rifle solely for subsonic use , and as such decided to use a 1-8 twist ( which is a tighter twist than the AI version ) .

The AI version uses a 1-9 twist & is designed to use 200gr subsonic ammo & normal std high velocity ammo , the suppressor will handle both & and is such is a multi role design .

I am not needing or wanting multi role .

 

I am not an expert , but believe if I used a shorter case I would have feeding problems with the action & mag design ( I would prefer to use a smaller case , like 30BR etc , as it would suit the subsonic use better ) , so its a compromise as I did not wnat to use a repeater action , only to have too load it as a single shot action .

 

As the case size is much bigger than needed , I use a special powder , Trailboss , this powder virtually fills the case , with around 12-13gr , and am using a 208gr Amax .

 

Cheers Chris

[c18rch]

Just done quick search for the BT mod. All it came up with is predictably a load of BT phone stuff.

 

Is there any information on it anywhere?

 

Rich

[eldon]

Just done quick search for the BT mod. All it came up with is predictably a load of BT phone stuff.

 

Is there any information on it anywhere?

 

Rich

 

Here you go Rich,

 

http://www.bt-ag.ch/

 

Bruger and Thomet not as you found British Telecom

[c18rch]

Cheers for that.

 

Rich

[ChrisF]

Heres a pic of it monted up with scope , sounds like a air rifle , very quite , the impact of the bullet into the backstop of dirt is the main sound .

 

weird thing , is I seem to get highest speed with the lower charge .

 

Used Trailboss , 12.0 , 12.5 & 13.0 gr with a 298gr Amax bullet .

 

Speed , 934 -1054 fps .

 

Need to re do , to back sure , all charges where weighed .

 

[baldie]

You are bang on with the trail boss Chris. The beauty of it, is that its safe. Pistol powders etc can, and do cause detonation. I believe more guns are blown up by people piddling around with subsonic loads and unsuitable powders than anything else.

 

I reckon the lower charges are giving you a more even burn rate, and you may even find unburnt powder in the mod from the higher weights.

 

Lovely gun mate, and worth the wait i know you,ve had.

[ChrisF]

Thanks Mate ,

 

Yeap , its real good so far , but in hind sight , knowing the time & drama involved , I would have just order 2 additional AI rifles , and have been done with it .

 

As to Dangers of Subsonic loading , I am well aware of all the problems , as I did some research about 10yrs ago on the net , and the MAN with the most of this LOST knowedge was a Finnish Gentleman , P.T. Kekkonen , I had the great pleasure of corresponding with him directly for a few yrs before he passed away , he is missed greatly .

 

I know most of the tricks with reloading this stuff , BUT stopped , and have only started back up , due to the unique properties of Trailboss powder .

 

And I agree , trying to make something do , what its not designed to do has lots of problems , the 308 has around 45gr plus of case capacity ( with normal rifle powder ) , and runs a 150gr bullet at around 2.5 times the speed of sound , then you want to put 10grs of pistol powder into it and have it run happly at just under 1x speed of sound , thats a BIG ask , and alot of air space left in the case .

 

Thats not mentioning twist/bullet/weight selection , as well as barrel lenght ( thru fiction ) , and different jacket metals etc , alot of stuff , and reverse logic for subs , better too high in powder charge , so bullet Exits the barrel , to incorrectly tightened / fitted cans .

 

With the Trailboss powder , its real light & fluffy ( ie low bulk density ) , 12-13gr of this stuff , almost fills the case to the bottom of the shoulder , so does not need a filler or glue to keep the charge seted down by the primer .

 

 

Cheers Chris

[terryh]

Chris,

 

You've obviously done your reserch here, nice set up.

 

A few years ago a UK smith was playing with sub sonic in 308. From memory he was using the Lapua sub sonic bullet and a pistol powder. One thing that stuck in my mind was to get very good accuracy (he was seeing 3 round clusters at 100 yards) was the sorting of brass by weight.

 

Don't know if this is of any help?

 

Cheers Terry

[baldie]

Reputedly another good one to try, powder wise , Chris, is Tin star. For the life of me i cant remember which manufacturer makes it, but its either Vhitavouri or Hodgdons.

 

Sorry if my post came across as you not knowing what you were doing with subs, not meant that way at all.

 

Over the years i have seen and heard of it happening locally to me a very great deal. I,ve lost count of the number of destroyed marlins i,ve seen due to miniscule loads of Pistol powder, and we regularly get folk in the shop who are playing with subsonic loads in .308 and .223, with very dangerous powders.

 

You cant cheat Darwin. His theory sorts the stupid ones out.

 

Must admit, its something i fancy a go at myself. I,ve built a couple of fast twist .308,s for subsonic loads for customers, but never had one myself. Have a look on this site, there is some very interesting gear on here, especially the .338Br !

 

http://www.silencertests.com/forum/index.php

[brown dog]

Reputedly another good one to try, powder wise , Chris, is Tin star. For the life of me i cant remember which manufacturer makes it, but its either Vhitavouri or Hodgdons.

 

Viht.

 

Used Tin Star in 308 in my AW courtesy of Ewen. From memory we were launching 180 smks through normal barrels and they were stabilising perfectly. Great fun to shoot - like an air rifle - and still zipped through 8" diameter logs.

 

As a contrast, tried some factory Sako subsonics through the conventional tube - wouldn't stabilise at all.

[ChrisF]

Hi Baldie ,

 

 

No problems , I thought you where just trying to point out that it is a tricky & dangerous business , which I agree with .

 

As to Tin Star , I ahve heard its not quite as good as Trailboss ( this was made to be fluffy & fill the old Blackpowder cases , like 44-40 & 45LC etc , because using modern powder instead of the blackpowder , you have a large space just like the 308 ) , in the 44-40 , the last part denotes 40gr of Blackpowder , but using modern powder you will be using a faction of this , leaving a large airspace .

 

PTK said the best powder to use for subsonic rifle apps , like 308 etc , would be the old shotgun powder , as this did not have the current modern coating to retard igntion , easy to make , just leave out the LAST manufacturing step , but so far no one does IT .

 

 

Cheers Chris

 

P.S. I think Tin Star is a VV powder

[Laurie]

Cheers Chris

 

P.S. I think Tin Star is a VV powder

 

Yes - correct. IMR Trail Boss works better in my limited experience of the pair (mostly in .444 Marlin) and certainly meters much better from a powder measure. As the names suggest, the original intended application was for Cowboy Action revolver loads, but Trail Boss works superbly with low MV loads using lead bullets in ANY rifle cartridge, and also it appears for subsonic / light loads using jacketed bullets too in many cartridges. For those who haven't seen it, the kernels look like miniature doughnuts, and the bulk density is so low that it's sold in 9oz bottles, that being all a standard Hodgdon / IMR plastic container will hold. Viht N32c 'Tin Star' has a similar burning speed to N320 pistol powder but is bulkier - but nothing like as bulky as Trail Boss.

[ChrisF]

RE: rarity of BT cans in NZ .

 

There are more than most people think , just because you donot see a lot of Kiwi's posting pics , dosn't mean , they are not in use .

 

Some guys , just donot put stuff , on the net at all , .

 

most in NZ , that do run BT cans , do so , because they use AI rifles , and as BT make cans for AI rifles and are linked to them , they buy them at the same time as they order their rifles & from the same agent .

 

Most of these are 338 cans & full suppressed AWs etc .

 

Later Chris

[tackb]

Hi Guys ;

 

Just finished a Subsonic build , basically a Suppressed AW clone .

 

Badger M2008 action , using BT can made for AI .

 

 

I had great success with unique in my 308 with a 180g round nose flat base at subsonic velocitys i'd need to check my data book but it was around 7 grains , one thing i'd recommend is shooting with the can off to make sure the bullet is stable first before you try the can so there is no chance of fouling the baffles this was all in my 20" remington based custom build and i've got some trailboss on order to resurect the project !

 

i was at 1-1.5 moa with my loads.

 

good luck it's great fun.

[ChrisF]

This is my 1st dedicated subsonic build , but its not my 1st experience of reloading a 308 cal rifle at subsonic speed .

 

And yep , I have a reasonable about of knowedge in this arcane art .

 

I have done the filler route w/ fast pistol powder , have tryed the drilling the fash holes bigger , about the only one , I have not tryed is using a glue / solvent to melt the top of the powder columb to stay in place .

[Ratwhiskers]

Sat (well laid up with the pooter actually, will explain latter) playin' with Tin Star/ Trail Boss loads over the weekend (Quick Load's bloody adictive once you get started with an idea in your head), and found I that l could run TB at near full case loads and reach between sub loads and good reduced loads for trainers/light recoilers . But TS only showed 45-50% fill to reach the same levels so l'm just a little leary to use it in consideration of a flashover/detenation .

 

The Ratel, thinks l'm either Nuts or l need stronger Meds to shut me up for good.