N/A Valve stem damage. Artemis m16a bottle

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SacramentoSam

SacramentoSam

Member
Dec 8, 2022
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Sacramento, California, USA
Hi all, noticing some damage at both ends of the stem. Trying to figure out muzzle velocity inconsistencies. I’ve already cleaned the regulator and put a Delrin seat in. That took away all the creep but now I’m noticing fairly consistent 4 -5 fps spread with an occasional 20 to 25 feet velocity difference every seven shots or so. I thought maybe the valve stem was sticking after seeing these marks on it. Any insight would be grateful.

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Granted its probably being driven through aluminum when actuated... those marks were likely made before the gun was assembled. I'd buff, polish, and see if there's any way to polish the areas in the gun that may have been roughed up by these score marks.

I'd say it would be importaint to first determine if these rough spots interface at all with any other parts in the gun.
 
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Long_Gun_Dallas said:
Granted its probably being driven through aluminum when actuated... those marks were likely made before the gun was assembled. I'd buff, polish, and see if there's any way to polish the areas in the gun that may have been roughed up by these score marks.

I'd say it would be importaint to first determine if these rough spots interface at all with any other parts in the gun.
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Thanks for the input, I was thinking along those lines as well... the mark nearest the seal seams to be a few thousandths in front of the stem channel. As far as I can tell, it doesn't contact other parts.

Polishing is on my mind as well, but there is a black (paint?) layer or something on there as well. removing that to polish might make the stem to small. The guns I have tinkered with before are usually not coated as far as I can tell and polish well. edit: after blowing the pics up on the computer monitor, it may be blueing.
 
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Yep likely bluing. I've had to polish a few on some guns. Even had some gall the valve pin hole it rides in. Polished it up with some play or slop. Not ideal, but I havn't detected any issues. In other words I wouldnt worry about making it under sized, just go easy and slow, and take the least amount off you can.
 
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bthurman said:
Yes polish the valve stem. Something else to look at. The m16a uses a pin to hold valve body in the receiver. Push it out and make sure not broken. This can cause valve body to shift slightly as well.
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I pulled the pin out. It’s not broken, but it sure is short. I couldn’t even see the pin from one side of the block. Replacing it with a full length stainless steel pin.

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SacramentoSam said:
I pulled the pin out. It’s not broken, but it sure is short. I couldn’t even see the pin from one side of the block. Replacing it with a full length stainless steel pin.

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Any other tips Sam on getting the rifle ready to shoot? I hav a 5L carbon fiber bottle ready to install when it gets here Tuesday FedEx. I hear that when Nate from Airgun Channel got his the trigger was set at 6 ounces which is awesome for target shooting. For hunting around 2 lbs for me otherwise!
 
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