170gr gas check subsonic

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grumpy429 posted this 2 weeks ago

I have 170 gr gas check mold for 30-30.  anyone have a sub-sonic load I could use in 308 and/or 300 blackout?

Texas will secede and take its place among the nations once more

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onondaga posted this 2 weeks ago

grumpy429,

Titegroup will work and have no ignition problems or position sensitivity. You will need a chrono. Start at 5 gr and get the velocity, then use reduction software for the speed you want. 975 fps will keep you subsonic in all conditions. Reduction software:

http://www.handloads.com/calc/reduced.asp

Reducing from a chrono speed with this free software will get you to within 1/10 gr of the exact velocity.

Gary

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grumpy429 posted this 2 weeks ago

thanks.  will give it a try

Texas will secede and take its place among the nations once more

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x101airborne posted this 2 weeks ago

Start at 4.0 grains of Bullseye and work up over chronograph. My 308 load for the 311-041 suppressed is 5.2 grains. For the 300 Blackout and same bullet, I use 4.6 grains. It wont cycle my AR without the can.

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Larry Gibson posted this 2 weeks ago

x101airborne's loads are pretty close to mine in the .308W with my Lyman 311041.  The fps alone won't tell you if the bullet is "suppressed".  Reason is it's the speed of the air moving around the bullet that creates the sonic "crack".  the blunter a bullet is, especially with a flat meplat, the slower it has to be to not "crack".  Start at 4.0 gr Bullseye and work up in .3 gr increment listening for a snap or crack right in front of the suppressor.  When you hear a snap or crack then back off .3 gr and you've then a "suppressed" sub-sonic load for that bullet I your rifle/suppressor.

Cant; say about the BO because I don't have one but start low and work up listening for the snap/crack then back off.

LMG

Concealment is not cover.........

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TRKakaCatWhisperer posted this 2 weeks ago

x101airborne's loads are pretty close to mine in the .308W with my Lyman 311041.  The fps alone won't tell you if the bullet is "suppressed".  Reason is it's the speed of the air moving around the bullet that creates the sonic "crack".  the blunter a bullet is, especially with a flat meplat, the slower it has to be to not "crack".  Start at 4.0 gr Bullseye and work up in .3 gr increment listening for a snap or crack right in front of the suppressor.  When you hear a snap or crack then back off .3 gr and you've then a "suppressed" sub-sonic load for that bullet I your rifle/suppressor.

Cant; say about the BO because I don't have one but start low and work up listening for the snap/crack then back off.

LMG

 

Hmmm.  What about the difference between tangent ogive and secant ogive?  Significant difference in long range ballistics due to the differences at the junction of the ogive and the cylindrical portion.  Is there a perceivable difference therefore in the audible 'crack'?

 

 

 

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Larry Gibson posted this 2 weeks ago

The difference between those two ogives given the same weight, style and caliber of bullet will probably be very small.  However, there will be a difference in fps where the "crack" is produced between the same weight/caliber bullets with a RN, a WFN and a spire point nose.  Many think they just must use a velocity just under the speed of sound, i.e. about 1100 fps.  Doesn't work that way as I found about 50 - 60 fps difference between a 311041 and a 311291.........

LMG

Concealment is not cover.........

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Coydog posted this 2 weeks ago

How will this sound when not use of a suppressor in a 308 win.? 

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Larry Gibson posted this 2 weeks ago

How loud w/o a suppressor?  With my hearing....not very,,,,,, but with yours?  There will then be muzzle blast but no sonic crack.  It will probably be fairly loud......to me louder than a 22LR HV and close to a 357 out of a carbine rifle with a 158/160 gr bullet over 6 gr Unique.  You will want to wear ears.

To get quieter w/o a suppressor reducing bullet weight, powder charge and velocity works best.  If that's what you're interested in I suggest a 90 - 105 gr bullet sized .311 and lightly lubed with LLA or a regular soft lube loaded over 2.7 - 3.2 gr bullseye.  If your .308W is a push feed, especially with a plunger ejector, and you plan on shooting this type of load several times in the cases you may want to drill out the flash holes to not larger than a #28 drill size.  That will alleviate the case developing headspace issues.

If you really want a "quiet" load with your 170 gr bullet then cast them very, very soft (30-1 alloy) and size .308/.309 (push through sizer to avoid scrunching the soft bullet) and lightly lube with LLA. Load in the fire formed cases with the flash holes drilled over Bullseye starting at 5 gr.  Work DOWN in .3 gr increments Until you get the noise level you can live with, don't stick bullets in the barrel, (the softer alloy will allow a lesser velocity before bullets stick but keep a steel cleaning rod handy and make sure the bullet cleared the barrel before firing another) or you run out of sight adjustment to come to zero.  This is the old Paco Kelly method and I have done so with the 6.5 Swede, 308W, 30-06 and 8x57 getting the velocity down to 300 fps with less noise than my 22 cal air rifle makes. 

LMG

Concealment is not cover.........

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Coydog posted this 2 weeks ago

Thank you Larry that will help

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