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Unequal daisy model 74s

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Daily shooter View Drop Down
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    Posted: August-22-2018 at 6:05pm
Bought two Daisy 74s and ran them across a Chrony right out of the box.
One shot about 310 fps within the first 20 BBs. The other one will sometimes
reach 200 fps, even after multiple co2 powerlets have been run through it. Following a
You tube video, I disassembled both guns and found no internal differences.
Even went into the power valve on the slower one and added Pelgun oil to the o rings there.
Can't find a reason for the fps difference between these two 74s.
Would appreciate your input and ideas to get the slower gun up to at least 260fps or better.
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BurghDude View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BurghDude Quote  Post ReplyReply Direct Link To This Post Posted: August-22-2018 at 8:37pm
There is a thread out there already. Search for Daisy 74 and it should pop right up. According to that, your 310 gun is an anomaly!:)
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cobalt327 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cobalt327 Quote  Post ReplyReply Direct Link To This Post Posted: August-22-2018 at 9:18pm
If you're careful you can dry fire the gun with one half of the plastic receiver removed. By doing this you can see exactly what's going on when the trigger is pulled. One area to look at carefully is the fit of the shot tube inside the front sight/barrel plug. Because these guns use the shot tube as the hammer, it must be free to move fore and aft w/o restriction. Another thing to check is to see that the spring that gets compressed as the trigger is pulled and then powers the shot tube/hammer rearward into the valve when the sear breaks to actuate the valve isn't somehow dragging or having it's movement hindered in some way.
 
The 74 uses a sintered filter so don't over oil the valve as it will take a long time to shoot the filter free of the excess oil. I used a small drop of oil on the tip each 4th cartridge and the gun ran fine that way. The filter can be cleaned using carb spray if the valve is disassembled.
 
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the fuse View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote the fuse Quote  Post ReplyReply Direct Link To This Post Posted: August-24-2018 at 12:40pm
I also bought two D 74's. Both shoot just under 200 fps and I have had them both apart checking all the issues described here. I have not modded them at all. 310 fps is real hot. The 74 is an oddball gun and prone to weird quirks......in my experience. Both of my guns prefer to be shot when cooler. The first five shots are real slow...... won't even chrony. From then on.....once the expanding gas cools the works down....they shoot at about 180-190 fps. Go figure. No other Co2 gun I have ever shot acts like this. All the other Co2 guns I have like it hot. Hmmmmmm. Still a fun little BB plinker. 
All I'm for is the liberty of the individual.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Daily shooter Quote  Post ReplyReply Direct Link To This Post Posted: August-24-2018 at 1:12pm
Hey Fuse, interesting story about your two 74s.
I have now found a structural difference between
my fast and slow guns. Not prepared to report yet
as I am still trying to correct and verify the solution.
Seems as though poor quality work in the build of
them can be blamed. I also found that Crosman co2
Powerlets do not readily fit unless forced into the 74,
actually too long and a bear to get back out. Umarex
co2 carts. fall right in and I favor them anyway.
Stay tuned, I'm still working on it.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Daily shooter Quote  Post ReplyReply Direct Link To This Post Posted: August-27-2018 at 3:47pm
A solution for a low power(170-180)fps model 74. First, my thanks to Cobalt for his fine research and clear reports on the 74. The slow gun I received had a problem within the Air Valve Assembly. The valve was further down inside the end cap by .002. The firing pin sits over the air valve and is pushed down by the rearward movement of the barrel, allowing co2 to propel the BB. Also the valve was seated to a greater amount from the bottom of the valve assembly end cap. Together this means the air valve had .0035 less travel downward to open for the co2. The firing pin was .397 tall in both guns. I reduced that by sanding down to .390. MV increased to about 250 fps at 84 degrees using daisy premium zinc(Walmart) BBs. A further reduction of .005 made no difference. The last thing I tried was to drill the air valve to 5/64 then 3/32. Now at 84 degrees using Daisy Avante Match BBs(they just came in), MV increased to the 290's and measured one at 322 fps. Accuracy was ok shooting at a shoot and see target 30 feet down the hall, at least not worse. I did have to move the sight elevator to it's lowest setting. So, unless you have two guns to make comparisons, I would say follow Cobalt's lead and drill out the air valve to 3/32 to increase MV in the Daisy model 74.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cobalt327 Quote  Post ReplyReply Direct Link To This Post Posted: August-27-2018 at 4:48pm
Thanks for the support! The following is very likely to be in the thread I linked to above but in case it isn't or was overlooked, it might be worth a look:
 

The travel of the firing pin (and the valve by association) is pitifully small stock. I measured it at 0.020". The problem with this is, the side holes are round and so the valve has to be compressed pretty far for the widest part of the holes to be exposed to allow gas to flow. I filed the side holes a little wider at the bottom, but it's easy to get into the area of the valve that seals against the valve seal- it's only a VERY narrow area that seals the valve chamber and if the valve is damaged a whole new $15.00 valve assembly would be needed.

 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote the fuse Quote  Post ReplyReply Direct Link To This Post Posted: August-28-2018 at 8:59pm
Hmmmmmm. More work than I will divert to a $35 plinker but I get it. You guys are way into this thing we have. Good for all of us that you are here. Thanks.
All I'm for is the liberty of the individual.
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