hammer springs

[RidgeRunner05]

I currently have a 12.5# spring in my .25 along with the WAR valve. I have gotten the itch to play with a little higher power with the rifle. I was going through my "gun box" the other day and came across some springs I have from tuning 1911 handguns. The reduced power spring packs have springs from 8-17#, and the high power packs go from 18-26#... the springs are the same o.d. as the marauder hammer springs, but will need some length cut off to keep the factory length. I will begin testing hopefully in the next week or so on the springs and some heavier slugs to see what kind of energy I can squeeze from the rifle while staying fairly efficient.

I will start testing when I get in some of the 48 - 49gr hunter supply slugs, because I am already super sonic with the 12.5# spring with max hammer throw and JSB's. 31gr barracudas yeild 950-980 as well. I haven't tried the eunjins due to accuracy reports being hit or miss.
Goals:
-Attain higher energy levels
-Stay around~950 fps max to maintain efficiency and accuracy
-Test velocity @ various fill pressures with different weight springs
-keep a "bell curve" in the shot strings
-Test with different spring lengths to see effects on velocity vs. Fill pressures and where it correlates with spring preload adjustment
-49gr slug @900-950fps for 88-100 FPE for as many shots as possible with the bottle kit.

The end goal I'm hoping for is 2 mags at high power for predator/ medium game hunts at no more than a 3400psi fill. <3000psi fill would be the optimum. Some modification to the bolt handle may be needed for extra leverage with the heavier springs.

I may be dreaming, but the only way I know is to try. Any advice on other alterations to hit high FPE? Without swapping to .224/.257 bullet barrel? That's being worked at a different angle in .357...

[RidgeRunner05]

Just a little update on my hammer spring "experiment".
I pulled the packages of the 1911 springs out to get measurements from them, as well as pulled the hammer spring adjuster from the m-rod. The springs I have go from 13#-26# The i.d. of the pistol springs was a little smaller than that of my 12.5# spring currently in the gun, so I used a drill with a 1/4" Allen bit to turn the adjuster screw while I sanded with 400 grit paper until the pistol spring would slip over the adjuster.




here is a pic of the 12.5# spring next to one of the 1911 springs. I plan on cutting the pistol springs long to begin with, just for experiments sake...



that's all I have for now. I have some 49gr slugs on the way from hunters supply as well as some 43gr eunjins from pyramid. I may do some testing with some 31gr Cudas that I have on hand in the meantime, though!

[Bob La Londe]

Looks like a fun and interesting project. I look forward to your slow motion video of heavy air gun slugs splintering out the back of 3/4 plywood.

[RidgeRunner05]

My slugs arrived from hunters supply today!





I ordered 250 of both the 48gr. hollow point and the 49gr flat point for testing. I'm hoping they have good accuracy for bigger critters, and small game too!

I am going to start my testing with a 20# spring, cut 2 coils longer than the O.E. spring. This will allow the spring to be under a little pre load with the rva adjuster fully counter clockwise. Cocking the bolt is a little stiff, but not overwhelming. Full coil bind on the spring comes at 4.5 turns clockwise, but it still cocks smoothly until bind. I plan on making a hardened sear to withstand repeated use with the heavier springs.

Another planned upgrade will be the valve retention screws. These will be upgraded to allow for a 3600psi fill to achieve maximum power. But for now testing will be done to a max of 3300psi

Hopefully I will have some chrono numbers in the next day or two. I'm looking forward to bringing out the beast in the m-rod!

[AwesomeAnt]

That's gonna be 1 beastly Mrod. I've been curious about the accuracy of the Hunter supply slugs. Good luck Bro.

[RidgeRunner05]

I had a chance to shoot a few rounds over the chrono this afternoon. The weather wasn't being cooperative, misting rain and cold weather didn't allow for a lot of testing but I did shoot a few strings with the 49gr HS slugs.

49gr HS flat point slugs
WAR valve (.187 tp and barrel port)
500cc bottle
20# spring (+2 coils longer than 12.5#)

HT- full ccw
HS- 0 preload
3200 psi to 2800psi
838,842, 839, 839,837,839,837,833

HT- full ccw
HS-1.5 turns c
3200psi to 2800psi
857,854,849,851,847,844,844,838

I stopped a with this string due to the fact that I was starting at the peak of the curve, or on the downward side of the curve at my fill pressure. My future plans for the higher fill pressures seem to be justified, but I want to see where I can get with the max 3200psi fill. I will cut the extra 2 coils from the spring and that should help bring the peak down to a lower pressure.

I have also cut down the 16 and 18.5# springs I have and will test them hopefully later in the week or over the weekend. Testing with the heavier springs will be held off until I can fill to higher pressures.

So for now, I am at 78ft/lbs with the 20# spring and 3200psi. And man do those slugs hit HARD. I can just imagine what they'll do moving a little faster

No accuracy report on the slugs as of yet.

[Bob La Londe]

I plan on making a hardened sear to withstand repeated use with the heavier springs.

So, how do you think you will go about that? Case hardening something easily grindable/machineable, or go with a higher carbon alloy that can be heat treated or get really creative and use a mild steel and "super quenching." I'm always curious what processes people use for this sort of thing since there are multiple approaches. Do you have an alloy in mind or do you think you will just use what you have handy and then figure out what process will harden that material?

Personally I tend to go with O1 or W2 for general hard metals work because their hardening process is so easy. I usually keep some O1 plate and bar on the shelf.

[RidgeRunner05]

I haven't really thought that far into making the sear. In the event that it is needed, I think I would rather machine the part from a stronger material though. I'm no engineer lol, just a tinkerer. But I do have a good friend that is an engineer that has a nice machine shop

[Doc]

I would machine it then case harden it.

[int3man]

I would machine it then case harden it.

Hi Doc,
How about Lasering it then Hard Face treating it. after polishing the sliding surfaces?