My Version of the Millenium Pumper

[rsterne]

The hammer experimenting and thoughts are continued here.... http://www.canadianairguns.com/showt...vel-Adjustment .... and the short answer is no, it's not necessarily bouncing, just limiting the lift....

Bob

[SeanMP]

Limiting the lift doesn't explain for me why the velocity is going down as the preload increases.

[rsterne]

If you look at the graph in the other thread I think it will be clearer....

Bob

[rsterne]

My version of the Millenium Pumper is finally finished.... It uses a .25 cal Lothar Walther barrel, a Disco main tube, and a Mac1 extended Billet linkage, and weighs 7.25 lbs. without the scope, which is a Leapers 4-16 x 40 AO MilDot.... Here's what it looks like....



The Boyd's Blaster thumbhole stock has a swell in the forearm right where you grip it for pumping, and was a perfect choice.... The pump stroke is long, but significantly easier at 1800 psi than the Carbine was at 1500.... I have pumped the gun by hand to 2000 psi, and I would consider that a safe upper limit.... Over 60 FPE with EunJins should be pretty easy at that pressure....



The pump actually works better than the one in the Carbine did, filling the 28.5 cc valve faster than the Carbine did its 27 cc valve.... It takes 80 pumps to fill to 1800 psi from empty.... The second graph shows the number of pumps to refill after each shot when the gun is set up for three shots of 40 FPE.... This gun actually takes fewer pumps while producing 40 FPE per shot than the Carbine did at 30 FPE per shot....



Filling to 1800 psi gives a choice of three different tunes just by resetting the RVA.... I can get 1 shot at 950 fps (51 FPE), 2 shots at 898 fps (45.4 FPE), or 3 shots at an average of 846 fps (40.4 FPE) within 30 fps (less than a 4% ES).... While the gun can be pumped to 2000 psi, I feel that these three settings give the best balance between power and pumping....



The graph above shows the velocity of the "next" shot in each string.... You can see that the 4th shot when the gun is set up for three shots of 40 FPE is still about 30 FPE.... plenty good enough for a close follow-up or a coup de gras.... I'm extremely pleased with the way this project turned out.... It surpassed all my expectations, and performs better than I could have ever dreamed or hoped for....

Bob

[remtom1200]

That is a fine looking rifle Bob!

[rsterne]

Somebody asked what the FPE was if I maxed out the settings at 2000 psi.... With 42.4 gr. EunJin Points, it hit 858 fps, which works out to 69.3 FPE.... Mind you, it took half the air in the valve to do that, and MAN was it LOUD !!!

Bob

[bitterman]

Wow amazing!!!!!! Very nice job! Very innovative as always too

Bruce

[notec]

Work of Art.......too bad these couldn't be mass produced

[rsterne]

Actually, all the major parts are readily available.... It uses a Disco tube and valve, MRod trigger group (could use that from a Disco), a billet 392 pump linkage from Mac1 (could use a Benji 392 linkage, the Carbine did), Crosman steel breech, etc.etc.... If you downgraded the power a bit, you could use a stock Disco valve and hammer, you could use a Crosman 24" barrel in .177 or .22 cal, or an MRod barrel in .25 cal turned down to fit the breech (the Carbine did).... My Carbine was made with nearly all Crosman parts, even the stock was from a Disco, simply cut in half for the pump handle.... That was part of the philosophy, to show what CAN be built to bring the pumper into the 21st Century....

Bob