QB Question.. Charlie!

[JTK]

Hi Bob,

I have a question. I am tuning my QB..  have done everything but am not understanding why the barrel port needs tobe drilled? the seal beteween the chamber and barrel is that not going to restrict the flow of co2 anyways? enlarging the barrel port does not seem like it will help?

JT

[mikeiniowa]

Most of us replace the factory seal with 1/4 OD X .170  ID ice maker tubing, opening the port in the barrel to .170 keeps the flow smooth.....

[JTK]

thanks Mike! where will I find the icemaker tube? 0.170 = 4.3mm? If I make the port oval in the barrel and the tube is round how will it line up? Also, do you have a pic of the tube?

thanks
JT

[mikeiniowa]

for the most part you don't need to oval port the barrel, if you are doing the extended wire probe drill the probe when you do the barrel, assemble the reciever with the bolt installed and the barrel, drill the barrel to .155 or .160 for the .177 and .170 for the .22, drill down until you have also drilled the probe on the bolt, take it all apart and then drill out the probe for the wire probe. kind of self centering so is easy, then cut the probe off at about a 60 degree angle at the rear of the hole you drilled, lines aeverything up nice and gets rid of the 90 degree angle which causes problems with the flow, go to your local hardware store and ask if they have ice maker tubing for refrigeraters, look at the box and it should give you the dimensions, if you can't find it let me know off the forum and I'll send you a foot or two, cost is like 9 cents a foot so the mailing is more than the cost,,give it to you for free.....Mike

[JTK]

Thanks Mike! all of that makes sense. I have centre drilled the stock probe for now to 3.5mm (0.137) and  enlarged the recieving hole in the probe accordingly. Does the extended probe make a lot of difference? I am thinking I will cut off the stock probe and use epoxy to make it 45-60degree angle and then install the extended probe should work right? Al the other work is done. Valve nicely mated with pin down to spring diametre and aluminiun front part actually drille 6 holes and grinded 6 sections out of the washer. springs sanded smooth wanna chrony it 1st now and then think if I need to do the probe extension barrel drill mod cause it certainly feels like it is shooting harder already.

Also I read in the tune by Craig pits that he sais you can remove the pierce pin when bulking.. I have a 79 so I assume I can remove it.. but how do you centre tha spring in the assembly if you do that?

JT

[mikeiniowa]

You can remove the pin when working on a 79, turn a shoulder on the head of the valve that fits inside the spring tightly, only about 1/16 inch deep, should keep the spring centered, don't cut the probe off and then drill it, it was drilled at the factory and the dimple from the original drilling will center you bit for the probe if you go that route, drill it  then cut it, makes for a oops free job,

[JTK]

thanks Mike! will go building and post some pics..

JT

[JTK]

@ .170 (4.3mm) at what point do you start to damage the pellet by pushing it over a hole that size?

JT

[mikeiniowa]

Have to smooth the inside of the hole in the breech, I use a sharpening stone for a chain saw blade in a dremel tool followed by hand sanding with 400-600 grit wrapped around a small drill bit.

[JTK]

thanks Mike. will give it a bash. gonna malke myself a breach riser as well.. when I free float the barrel is it recommended to put another grub screw in to hold the barrel more secure?

[JTK]

is the idea behind the probe mod that the whole pellet is seated in the rifling and not just the head?

[mikeiniowa]

My rifle has a free barrel and only uses the factory set screw, if you want to go for it, try it with just the one then see if it needs another, I have slid rubber tubing over the barrel to eat the vibration, looks funky but works.....

[mikeiniowa]

Also helps get the gas flowing, it will use more gas per shot,

[JTK]

Thanks Mike for all your assistance. Have done just about everything other than the riser and probe..  gonna crony it today to see where it is at.

JT

[JTK]

Hi Guys..

done the valve turning, drilled valve assembly(alu part), drilled the washer, drilled the barrel, drilled the bolt front. Up about 50fps will do about 670ish with jsb's I think. Havent replaced the breach seal yet.. cant find the damn poly tube. man what a pain. dont even know what it looks like so I cannot realy find a substatude. Went to a paintball shop and got an extension tube. Is very hard so I am not sure it is the same thing. But if it works it will at least not be freeze sensitive. I hope the seal will bump up the fps significantly. I see that I am waisting a lot of co2 as I can see lots of co2 vapors after the shot out of the barrel, or is this normal? Also still need to do the probe mod.. still not sure about it though. The standard probe seems like a good design once drilled as it directs the co2 directly on the backof the pellet and not on the skirt with nothing on the centre.. but then you guys have tested this extensively and I trust ya all..  what else can I do to up the frames? load the hammer spring? also going to remove the pin..

JT