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Post by zerodown on Mar 20, 2013 12:56:25 GMT -8
Does anyone know what the gas port size is on the 18" 6x45 barrel? I've been trying to get my gun to run with a rifle length gas and collapsible stock. Its finally running with a regular carbine buffer and 3 coils cut off of a stock spring. It just doesn't seem to be getting enough gas. Gas block, tube, BCG, rings, have all been replaced and ruled out.
I don't think its the ammo either as I'm shooting a 85gr TSX over 24gr of H322. They are pushing almost 2800fps with some minor primer flattening. They should be hot enough for this configuration. Same effect with 95gr partitions over 22.5gr of H322.
I'm wondering if the gas port is undersized.
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Post by GLSHOOTER on Mar 20, 2013 13:10:01 GMT -8
Does anyone know what the gas port size is on the 18" 6x45 barrel? I've been trying to get my gun to run with a rifle length gas and collapsible stock. Its finally running with a regular carbine buffer and 3 coils cut off of a stock spring. It just doesn't seem to be getting enough gas. Gas block, tube, BCG, rings, have all been replaced and ruled out. I don't think its the ammo either as I'm shooting a 85gr TSX over 24gr of H322. They are pushing almost 2800fps with some minor primer flattening. They should be hot enough for this configuration. Same effect with 95gr partitions over 22.5gr of H322. I'm wondering if the gas port is undersized. The first step is define not running. Failure to extract, failure to feed or failure to lock back? Greg BTW welcome to the board. |
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Post by zerodown on Mar 20, 2013 17:00:08 GMT -8
Thanks for the welcome. Bolt wouldn't lock back and FTFs. Ejection is fine at between 3-4:00 although on the light side. I basically got the guts as light as I could (BCG, Buffer, Spring) and it just has enough now to make it happen.
I mic'd the port on this barrel at .093. I would have said this is fine for 5.56 but I'm new to the 6x45 and not familiar enough with the pressure curve. Does BHW drill the ports on this barrel to .093 or did it get undersized?
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Post by GLSHOOTER on Mar 20, 2013 18:48:18 GMT -8
Thanks for the welcome. Bolt wouldn't lock back and FTFs. Ejection is fine at between 3-4:00 although on the light side. I basically got the guts as light as I could (BCG, Buffer, Spring) and it just has enough now to make it happen. I mic'd the port on this barrel at .093. I would have said this is fine for 5.56 but I'm new to the 6x45 and not familiar enough with the pressure curve. Does BHW drill the ports on this barrel to .093 or did it get undersized? I would call BHW and ask to speak with Andy. I am not sure of the size but a rifle length on an 18" is on the ragged edge of reliability in a 223 based case. It may well need to go up to about 0.098. IIRC someone on here did that before on theirs but check with Andy about it. Simple to do and if that's what it takes and it were mine I would be doing the fix in my garage. Greg |
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dr69er
Senior Member
Protect the US Consitution & the American Way.
Posts: 222
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Post by dr69er on Mar 20, 2013 19:46:50 GMT -8
Thanks for the welcome. Bolt wouldn't lock back and FTFs. Ejection is fine at between 3-4:00 although on the light side. I basically got the guts as light as I could (BCG, Buffer, Spring) and it just has enough now to make it happen. I mic'd the port on this barrel at .093. I would have said this is fine for 5.56 but I'm new to the 6x45 and not familiar enough with the pressure curve. Does BHW drill the ports on this barrel to .093 or did it get undersized? I would call BHW and ask to speak with Andy. I am not sure of the size but a rifle length on an 18" is on the ragged edge of reliability in a 223 based case. It may well need to go up to about 0.098. IIRC someone on here did that before on theirs but check with Andy about it. Simple to do and if that's what it takes and it were mine I would be doing the fix in my garage. Greg I would agree with Greg on this topic...I had a similar Issue w/ a non BHW 6x45 rifle barrel...had to go to .098" gas port diameter to get full cycling (rifle gas system). Sometimes this also happens with a rough chamber that slows down extraction enough to cause Issues...(unlikely to happen with a BHW barrel though). Also keep in mind this often happens with a 18" Bbl. using a rifle length gas system, there is not quite dwell time before the bullet passes the gas port for it to maintain gas pressure... Good luck. |
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Post by zerodown on Mar 21, 2013 11:07:43 GMT -8
You guys were right. I took my frustration out on the barrel last night and drilled the port to .102. Now it runs like a dream. No problems at all with a ST-2 buffer and full carbine spring. Turned down the gas block a bit and she's nice and smooth. This is from today with the Barnes 85gr TSX over 24gr of H322 using an EOTech and 3x mag. I'm sure it would make jagged holes with a regular scope. Can't wait to take it pig hunting next week.  |
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dr69er
Senior Member
Protect the US Consitution & the American Way.
Posts: 222
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Post by dr69er on Mar 21, 2013 14:33:28 GMT -8
You guys were right. I took my frustration out on the barrel last night and drilled the port to .102. Now it runs like a dream. No problems at all with a ST-2 buffer and full carbine spring. Turned down the gas block a bit and she's nice and smooth. This is from today with the Barnes 85gr TSX over 24gr of H322 using an EOTech and 3x mag. I'm sure it would make jagged holes with a regular scope. Can't wait to take it pig hunting next week. Glad to see it all worked out...although, a .102" diameter is a tad bit on the large side but it should be fine for your application. |
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