Canadian Airgun Forum

OK, so here's what I found out when I pulled the DAQ hammer out today.... First, some dimensions....

Hammer
Weight: 177 gr. + cocking lever (15 gr.) = 192 grams total
OD: 0.995"
Length: 2.36"
Bore for spring: 0.516"
Depth of bore: 2.10"
Stroke: 1.62"

There is a flat milled along the bottom of the hammer for the sear to slide on.... The sear catches on the square front end of the hammer (which is hardened) when cocked.... There is a milled notch for the sear to catch on to keep the hammer from sitting on the end of the valve stem, providing a "safety catch" to allow filling the gun without fully cocking it.... The aft end of that notch is showing wear from hitting the sear already, in about 100 shots....

Spring
OD: 0.505" +/- 0.002"
Wire: 0.062"
Coils: 25
Free length: 5.44"
Preload: 1.20" (uncocked)
Cocked length: 2.62"
Compression (cocked): 2.82"

The spring appears to be hand made.... The coils, particularly at the ends, are not perfectly spaced, and the ends of the spring are not bent down (closed) to contact the next coil, merely ground off on an angle.... There is a shouldered plastic spring guide that fits into the end cap which is drilled 0.516" to locate the spring.... The knurled end cap is threaded into the end of the main tube, and prevented from rotating by the rear breech screw.... To be frank, the quality of the machining inside the tube where the hammer slides is quite rough.... Of everything I have seen thus far, this bothers me the most.... Because of the design of the end cap, I think the easiest way to make a velocity (preload) adjuster would be to use a relatively small (1/4" or less) diameter fine thread screw and counterbore the spring guide for the end of it.... The only thing that bothers me about that is that once the shoulder on the spring guide moves very far, the spring will no longer be contained by the hole in the end cap.... In addition, there is no simple way to REDUCE the preload as the guide is already bottomed in the hole in the end cap.... Since the whole point here is to reduce the preload, I decided to look at modifying the spring....

I could have simply cut off a coil or two on the spring, but the uneveness of the coils bothered me.... This usually indicates that he spring has never been "set".... ie collapsed completely to coil bound and then allowed to spring back.... When you set a spring, the coils rebound to an even spacing, at least even enough that you can't see it with the naked eye.... I slid the spring over a piece of 3/8" threaded rod with a nut and washer on each end and proceeded to collapse it.... I first wound the nuts in until the spring was at its "cocked" length (2.62").... The coils were pretty much all over the place for spacing.... I wound the nuts in another 4 turns (1/4") and let the spring rebound and measured it's free length.... It had just begun to collapse, the free length had shortened by about 1/32".... I repeated the operation, going 8 turns beyond the cocked length.... The spring was beginning to look better, with more even spacing between the coils as the ones that had the bigger space collapsed first.... The spring rebounded to 5.25", so it had collapsed about 0.2".... It looked MUCH better, the spacing appearing much more even.... I checked the OD, and it had only increased about 0.001".... Encouraged, I went another 4 turns, so that I had now compressed the spring 3/4" more than it's cocked length.... The distance between the coils was now becoming much more even, and the free length was now down about 0.35".... I went another 4 turns, and the spring was now looking very nice, straighter, very even coil spacing, and nearly coil bound.... When I released it and checked the length, I found that it had collapsed a full 1/2", with the free length now measuring 4.94".... It had taken a full inch of compression past the original cocked length to achieve this result.... The spring coil spacing was now very even, and the spring was also straighter than when I started, indicating that every coil was now more symmetrical....

I checked the spring rates using a web based calculator, and in both cases, it says the spring rate is 9.9 lb/in.... so now I know that "setting" a spring doesn't change the spring rate, only the free length.... Here is how the spring compares to what I started with....

Preload: 0.72" (instead of 1.22") Force = 7.1 lbs (instead of 11.9) - a reduction of 40%
Compression (cocked): 2.32" (instead of 2.82") Force = 23.0 lbs (instead of 27.9) - a reduction of 18%

Lloyd shared his hammer spring energy calculator with me, and it gives the following results:

Stock spring
Hammer Velocity = 70.4 fps
Energy = 1.63 in.lb.
Momentum = 0.72 in.lb./sec.

Set spring
Hammer Velocity = 61.0 fps
Energy = 1.23 in.lb.
Momentum = 0.62 in.lb./sec.

If I cut 3 coils from stock
Hammer Velocity = 61.9 fps
Energy = 1.27 in.lb.
Momentum = 0.63 in.lb./sec.

What do these numbers mean?.... I dunno, but I'm sure I will begin to understand them as I get more data.... I do know that setting this spring produced similar results to cutting off 3 coils in terms of the effect it should have on the hammer strike.... I don't have a backstop that I can fire the DAQ into inside as of yet.... but I decided that one test I could do was to see how much air pressure it dumped with the set spring installed but no bullet.... It now dumps 300 psi per shot.... I assume that it would dump less with a bullet in place.... and I don't have a comparison for how much pressure it would have lost with a dry fire when stock.... but my gut feeling is that I'm going to be close to what I want.... I asked my wife if she could hear me shooting in our detached garage, and she said no, which is a good sign.... That means that if I have a backstop strong enough I can at least do some Chrony readings without having to go out to our camp.... That's a good thing, because it snowed today.... so my days at the camp are likely over for the year.... The plan is to make a temporary backstop from some timbers and find out what the velocity is and the air consumption.... If it turns out I need to detune the gun more, then I'll shorten the spring a coil and try again.... If it turns out that I've already gone too far, then I'll either make a new spring guide, a spacer for the end of the spring inside the hammer, or an RVA....

Stay tuned....

Bob

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Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal; Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
Proud Member of the 2000+fps Club!

I read all 3 pages and this was very interesting,
I will wait for the updates thanks for posting this for us to read.

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Custom Design by ME PCP/HPA Air Carbine 10-50X60 Scope My 2018 FT Open

Well I couldn't wait to try it out.... I got a 12" log about 16" long to use as a backstop and tried a few shots with the hammer spring I modded yesterday.... At 3000 psi, the first shot was 856 fps.... 20 fps MORE than stock.... I did a shot string starting at 3300 psi (my hand slipped, really it did!) and got the following....

882 fps (206 FPE)
858
824
797

There was 2100 psi left, so the gun was still using 300 psi per shot.... Way better than stock, but the hammer spring was still too strong.... By now I'm convinced that Dennis used the wrong hammer spring, so I pulled the gun apart and modded the spring some more.... This time I closed the end two coils to that they sit nice and flat.... I then fully set the spring, completely coil bound.... and then sanded the end two coils flat.... The spring is now only 4.50" long (neary an inch shorter than stock) and has 23 active coils instead of 25.... The spring rate is therefore higher, at 10.8 lb./in.... I ran the numbers through Lloyds hammer spring calculator and got the following....

Set spring, 23 active coils
Hammer Velocity = 53.6 fps
Energy = 0.95 in.lb.
Momentum = 0.55 in.lb./sec.

By now I'm wondering if I went too far.... I reassembled the gun and took a dry shot at 2500 psi (that was in the gun) and it was obviously working (not valve locked) so I filled it to 3000 and fired one over the Chrony.... 835 fps, the same as it was stock.... Now was the time to shoot some serious strings....

I filled to 3200 psi, and shot 6 shots before it fell below 800 fps.... WOW! that's 6 shots faster than the stock rifle's second shot.... .... I shot several strings, a few from 3200 and then gradually less as the tank pressure dropped, stopping at a 2900 psi fill.... In every case, the string used 950 psi for 5 shots or 1150 psi for 6 shots.... less than 200 psi per shot.... That is less than HALF the air the gun was using stock....



The graph above also shows the stock performance.... Starting at 3000 psi I was getting only 3 shots, with the second shot under 790 fps.... With the modded hammer spring I'm getting 6 shots from a 3200 psi fill (5 shots from 3000) with the same maximum velocity and the last shot is over 790 fps.... Here is the summary....

Stock
3 shots averaging 787 fps (163 FPE) with the velocity dropping like a stone between shots
400 psi per shot (0.39 FPE/CI) - and the gun was VERY LOUD as a result

Now
5 shots averaging 825 fps (180 FPE) between 811 and 833 fps
<200 psi per shot (0.88 FPE/CI) - over twice the efficiency with the gun MUCH quieter
6th shot at 792 fps is faster than the second shot from the stock setup

Is the 3200 psi safe?.... Well, Dennis has an article about the Exile on his website that talks about using 3200 psi, so I would presume if he felt that was unsafe he would have either not used it, or put in a disclaimer.... I'm not going to worry about it.... Had I used a 3200 psi fill on the stock gun (I actually did try one string), the shots would have been 855, 808, 760.... That gives an average of 808 fps (172 FPE).... While the first shot is stronger than the gun shoots now, the average over those three shots is less than I get over 6 shots now.... I think that's a darn good tradeoff, so the gun is going to stay the way it is for a while.... There remains one unexplained anomaly, however.... With the intermediate spring setup.... I got a shot at 882 fps (206 FPE) at 3300 psi.... and 855 fps at 3000 psi.... That is significantly stronger than the gun shot stock and I am at a loss to explain it.... unless the gun is simply wearing in a bit....

Bob

_________________
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal; Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
Proud Member of the 2000+fps Club!

Making good progress Bob.

Would like to know reservoir dimensions and sealing diameter with valve fastening details.

There are fans of DAQ that are filling their guns to 4,000psi...... curious about that. Officially they are 3,000psi MAWP design.

Walter.....

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Walter

Well if my hammer spring is typical, I can well believe that you would get better performance (and maybe an actual bell-curve) by filling it to 4000 psi.... I also would want to do the math before trying something that drastic....

I have no reason (other than curiousity) to pull the gun apart further than I have already.... It appears to be a two piece tube, and there are no fasteners between the valve and the front of the tube (air reservoir) so I'm guessing they are threaded together.... The piece of tubing aft of the valve (ie the hammer housing) is bored out (and very roughly at that) to about a 0.060" wall.... but of course that sees no pressure....

Even with the hammer spring I have now, it would appear that the shot string would benefit from filling to higher than 3200 psi.... What I am accomplishing by using that fill pressure is one additional shot right at the average velocity.... Would an additional 200 psi give me another shot?.... Probably, but I won't find out unless I do the math first.... or hear from reliable sources that it's OK to use 3400-3500 psi....

Bob

_________________
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal; Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
Proud Member of the 2000+fps Club!

Bob, the only way to know the tube design is to thread it apart and measure it up.

Would also like a pic of the valve out of the reservoir. IIRC DAQ seals his tubes at the outer most diameter. To me that is poor design in that the threaded tube is under tension plus hoop stress of the pressure. The thinning of the tube wall for the oring seal reduces strength there as well. Hoping I am wrong about how he builds them when the fellas on the Adventures in Airgun Hunting forum have no issues 'over-filling' the tubes in the search of power.

Would expect the tube to be 0.125" wall but could be 0.095" and reduced to 0.045" wall with 20tpi threads. That is not that much meat when the diameter is large 1.250" IIRC.

Would love to see a full strip of the legendary DAQ bigbore rifle. A pic of that trigger would be swell as well.

Walter....

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Walter

The tube is 1.125" OD....

Bob

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Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal; Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
Proud Member of the 2000+fps Club!

I hate to think a gun that cost that much needs that much work to shoot properly

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VE7SHM//VE7ZJ

Moderator

Fair comment, and I agree with you 100%....

Bob

_________________
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal; Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
Proud Member of the 2000+fps Club!

well it's just like buying a nice car and adding nice things to it to make it go faster and look better
Nothing wrong with that, and I'm sure he had a blast doing all that work to his gun.

But thats just the redneck in me talking, [ But I would have done the same ]

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Custom Design by ME PCP/HPA Air Carbine 10-50X60 Scope My 2018 FT Open

How utterly pompous, and arrogant of you.
Dennis Quackenbush is a respected innovator and manufacturer of fine airguns for decades now, and you, a vertual newbie, that has had one of DAQ's guns in hand for a month or two consider yourself qualified to make such a critique???
I have to wonder just how Dennis would respond to such a blatantly outrageous statement?
Perhaps this thread should be brought to Dennis' attention so that he can respond to your criticism of his work?

I missed this BS on my first quick scan through of the thread, and now I wish I hadn't taken the time to give it a second look when it came back to the top.
I had to think long and hard about responding to this thread, but finally decided that someone had to deflate that enormous ego of yours, and put some perspective on things.

rsterne - built a few modded Crosman airguns over about 3 or 4 years.

DAQ - designed and manufactured quite literally hundreds of airguns of various descriptions over several decades, as well as making aftermarket parts for the various Crosman and other airguns.

And you accuse others of being "full of themselves"????

I would send it back...A gun that expensive should be able to cook breakfast for you everyday like my AA does

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"It's just a springer..."

just reading thru this and im surprized by the spring being wrong for the gun . as supermatic said .
but what you have found seems to be the better way . i do wonder what dennis would say , maybe they were planing on the gun being a 4000psi not a 2800-3000 like most . or maybe they buy springs that work for all guns from 3000-4000 .

I just thought Bob was commenting on the fact there could be a better spring to use, not that the guns performance was crap from the spring it came with! It is a beautiful looking gun and that Dennis guy does great work, was just checking out the web site.

I would worry more about the seals holding when that huge bear was coming at me full tilt.

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"Lust is the craving for salt of a man who is dying of thirst"
-Frederick Buechner-

incase you're serious, that rifle would only piss off a bear..