Even the softer spring used in CO2 variants is a known bolt handle breaker. I can imagine DF MKII spring must be a tough one to cock since it's stiffer then the HPA spring! I broke several bolt handles before finding this listing for upgraded handles.https://www.ebay.com/itm/294824411242?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=nDiEtpX1TO-&sssrc=2349624&ssuid=coq08-wmSMS&var=&widget_ver=artemis&media=COPYSo far so good and the extra leverage is much appreciated. I got the brass ball and steel drum, but wish I had gotten the steel ball instead.
Hey guysHere is the next step I did today on the DF II, 22 cal.I tore it down and removed the OEM hammer/spring, did some careful measuring of the hammer spring tunnel, I had to open it up to .420" I/S diameter, I only removed .020" of material,the hammer was not harden and cut very easy with Carbide tooling.After boring the spring tunnel out, I polished the inside and also polishedthe inside of the pressure tube, where the hammer was operating in, that had lots of burrs and very rough etc.Cleaned everything up added some lube and reinstalled the hammerand a 5" long, 11# Flat wire spring, had to make a new spring guide also.(OEM Hammer spring is 18/19#'s at max compression, (coil bound), 3.150" long,.390" dia O/S dim, x .300" I/S dim, with 15 coils.) I did a my usual 5 shot/5 pump chrono test and was very surprised,here is the test results, a running total,1. OEM stock 2. Pump head lengthened 1 full turn, 3. Open hammer spring tunnel added a 11# Flat wire spring. I just got thru running a chrono test (OEM STOCK RIFLE) on my new Dragon Fly II (Refub),and got these results, with my Chinese chrono:1. Chrono test5 shot group at 5 pumps averaged 546 fps for Crosman HP,5 shot group at 10 pumps averaged 640 fps for the same above ammo.This chrono test is with the pump head lengthened 1 full turn from the OEM setting,2. Chrono Test5 shot group at 5 pumps averaged 556 fps for the Crosman HP,5 shot group at 10 pumps averaged 668 fps for the same ammo.This chrono test was with the hammer spring tunnel opened to .420",and with a 11# Flat wire spring, 5" long, same ammo as above,3. Chrono test5 shot group at 5 pumps averaged 631 fps for the Crosman HP pellets5 shot group at 10 pumps averaged 684fps for the same ammo. I am double checking everything to makes sure I did not make any mistakes.Your thoughts and suggestions...............Tia,Don
DJYes, I call the spring hole inside the hammer a spring tunnel. I did make a new .250" spring guide out of black Nylon rod I had in the shop, same dimensions as the OEM only .250" diameter.I don't believe that they are retained air pumpers, I check every shot and have NOT found any retained air left from the pumping,with the OEM or the Flat wire springs being used..I don't know what you mean by "MSP"?When you use these FW springs for the first time, be sure to use them full length, then after testing, you can clip a 1/4" off at a time to get where you want to go.These FW springs do NOT stack like round coil wire springs, they take some getting used to.I have the ISMI FW springs in all weight ranges, then use a spring that will work the best,I start with the light weight (full length) then go up 1 weight step as needed. Be sure to set the spring before you use it, (setting the spring means to take and compressthe spring to coil bound, no space between the coils, I do it 3 times), then use the spring.I think these springs allow the hammer to stay in contact/open the valve a bit longer, as they are slower acting while compressing the spring.A sharp rap -vs- a slightly long slower push?? I remember Wes Bob using lighter hammer spring and having a good gain in ballistics,on one of the DF II posts etc.Your thoughts and suggestions.........Tia,Don
DjI haven't checked my other Storm Rider 17 cal rifle and I have a Varmint one in 22 cal on the hammer spring spec's. Once I finish that, I'll add the info here, hopefully this will help the next shooter coming along,I have a strange bug for a DF II in the following calibers 17-20-22-25.I know that a DF II will become a 20 cal to tease my Dan's............LOLI just finished the 1 thru 10 pumps x 3 each per pump, and this is the chrono results,with Crosman 14 gr ammo, pumps were a complete cycle, open then closed arm pump arm,per pump stroke.11# Flat Wire spring, full 5" length, 1 complete turn on pump rod, nothing else changed.1 pump = 288 fps2 pumps= 321 fps3 pumps= 354 fps4 pumps= 561 fps5 pumps= 597fps6 pumps= 610fps7 pumps =616fps8 pumps =620fps9 pumps =656fps10 pumps =688fpsNo remaining air in pressure tube for any shot. I just hope that the accuracy is there,so far every shot taken has impacted the targets out to 50 yds, this is with iron sightswhich are hard for me to see........ Your thoughts and suggestions.......Tia,Don