Author Topic: Millennium Pumper Production - The Beginning - And The Lousy End (Read 292326 times))

rsterne · « **Reply #440 on:** February 23, 2015, 12:35:05 AM »

Intentionally running zero, or near zero, preload.... is an invitation to air wasting hammer bounce.... You are usually better off to have significant preload on a soft spring.... or often better yet, negative preload on a short stiff spring (ie rattling around loose when uncocked).... There are exceptions, and every design is an individual.... but that is the trend I am seeing again and again....

The two springs I tried on the Millenium Pumper were a QB spring (0.33" OD x 0.047" wire x 2.3" long) and then one 0.30" OD x 0.045" wire x 2" long, with a rate of 18.7 lb./in.... The final results were with the shorter spring.... Preload is 3 to 4.5 turns out from coil bind for the three strings, as noted on the graph....

Bob

CarsonRatSniper · « **Reply #441 on:** February 23, 2015, 12:54:51 AM »

I'm currently using a 2" x .360" diameter spring - I think its .045 or .047 wire...it is a 10# spring.

I also have a 1.5" 12# spring (same OD) that works incredibly well in my Challenger when tuned for pellets.

Thanks for the input Bob - I will play around with hammer weight.
The 2" spring and my 84 gram hammer had bounce - the 74 gram hammer wasted a bit of air...I will increase the weight of the current hammer I'm using (I haven't weighed it yet) in 5 gram increments and see what happens.

My Challenger works very well with the 1.5" spring left sloppy loose like you suggested - it only uses 15 psi per shot and is still shooting Kings @ 900 fps!
Maxed out the Kings do 1200 fps.

I'm trying to replicate that tune - the difference is I'm running a tapered spring inside the valve.
I need to order some of those you suggested for the Disco from Century and see how they work...it might be the perfect recipe with my current hammer assembly.

Mike

rsterne · « **Reply #442 on:** February 23, 2015, 01:00:24 AM »

With the MRod poppet, you should be able to run less spring, and it looks like you are.... My spring rate was 18.7 lb/in.... The smaller stem of the MRod poppet should require less hammer strike for the same dwell....

Bob

Rivers3Plinker · « **Reply #443 on:** February 24, 2015, 03:39:56 PM »

I just want to say thanks.
I found this thread two nights ago and have been devouring the information. One of the coolest gun concepts I have ever seen!
The level of knowledge and information here is really amazing.
I have been looking at those thumbhole stocks on the discosrus site lately too and I think it's a great choice.
Like some others here have stated, wish I had a grand to dump on the MP because I'd do it for sure.
Nice work guys.

jvanschoonhoven · « **Reply #444 on:** February 25, 2015, 10:07:29 PM »

Its definitely going to be an amazing rifle. I have one of the first 10 on order and am getting the shrouded version in .25 should be a hunting machine!

UCChris · « **Reply #445 on:** February 25, 2015, 11:39:49 PM »

I have been thinking, and this gun would be the coolest thing for a full night of coon hunting.

Man, how I wish I had a grand that didn't have to go towards college!

jvanschoonhoven · « **Reply #446 on:** February 26, 2015, 12:19:39 AM »

Just start saving now! LOL.
I think I am going to need another barrel. I got the 25cal on the way but thinking about getting a .22 for the smaller critters. I know the shrouded 25cal will be quiet but a .22 would be super quiet and great for most little critters around here.

Habanero69er · « **Reply #447 on:** February 26, 2015, 06:47:01 AM »

Quote from: jvanschoonhoven on February 26, 2015, 12:19:39 AM

Just start saving now! LOL.
I think I am going to need another barrel. I got the 25cal on the way but thinking about getting a .22 for the smaller critters. I know the shrouded 25cal will be quiet but a .22 would be super quiet and great for most little critters around here.

Instead of changing barrels for shooting "smaller critters", why not just use fewer pumps? Isn't that the point of a MSP? Seems to me the more you monkey around with a rifle that is shooting well, the more likely you're going to have issues with accuracy & always have to be readjusting, re-sighting in, wear & tear on screws & hardware, etc. Maybe it's just me, but once I get a rifle shooting right, I leave it alone & enjoy it's accuracy. Especially a custom built one.

jvanschoonhoven · « **Reply #448 on:** February 26, 2015, 12:49:41 PM »

I would normally agree with you however These rifles are actually being built to switch calibers. You can buy the whole kit with .22 .25 and .30
the reason to switch to .22 is that it will be quieter and cheaper ammo and more shots before pumping.
Ultimately I am sure I will end up with 2 rifles but till then ill get a caliber conversion.

rsterne · « **Reply #449 on:** February 26, 2015, 12:59:47 PM »

Either method will work.... I can't imagine using a .30 cal and turning it down when shooting Starlings, but it certainly could be done.... The gun will react like a PCP to tuning, you can reduce the hammer strike and use a lower fill pressure to produce more shots at lower power with fewer and easier pumps per shot....

Bob

jvanschoonhoven · « **Reply #450 on:** February 26, 2015, 01:26:16 PM »

I agree with you Bob it can be done either way.
Getting down to say 12fpe with a .25 jsb king comes in at 462fps that makes for a lot of bullet drop. Vs the .22 Crossman premier 14.3gr at 614fps
That was just an example I like around 850fps with the premiers out of my FX but it all depends on what the gun likes for accuracy.

rsterne · « **Reply #451 on:** February 26, 2015, 01:35:54 PM »

Yeah, c'mon you guys.... no way are you going to be happy with 600-700 fps when the gun will do 800-900.... *grin*.... You'll just grab another gun for plinking....

Bob

Nomadic Pirate · « **Reply #452 on:** February 26, 2015, 02:23:02 PM »

Quote from: rsterne on February 26, 2015, 01:35:54 PM

Yeah, c'mon you guys.... no way are you going to be happy with 600-700 fps when the gun will do 800-900.... *grin*.... You'll just grab another gun for plinking....

Bob

yep