new to me Extreme .457

[dyotat100]

What size is the hole the poppit is covering and what is OD of poppit?

How heavy is the hammer?

[Wayne52]

Very nice numbers with that beast !!! It's good to see someone actually using one of the older "Extreme Big Bore" guns again.  I never even realized that Brent had thrown in the towel regarding his business with building his big bores but glad to hear and see that someone else has taken over the building of them.  

[mackeral5]

Very nice numbers with that beast !!! It's good to see someone actually using one of the older "Extreme Big Bore" guns again.  I never even realized that Brent had thrown in the towel regarding his business with building his big bores but glad to hear and see that someone else has taken over the building of them.

It is indeed a beast....I hope to he able to somewhat tame it into a little bit less of a beast with a little more refined of a shot string.  A few nice and even shots of 425-450fpe is a lot more attractive to me than 1 shot of 515fpe then a second at 405fpe.

 I do acknowledge that I will be going somewhat backwards from what the design's original intent was.  The manufacturer  is named "Extreme" afterall......I think wherever the tune ends up it will still be possible to put it back into beast mode by  throwing an excess of hammer strike at it and likely build MORE power than it was delivered with.

My intent is for any of my changes to be reversible back to as delivered if necessary....

The gentleman that took over manufacturing seems to have a genuine interest in both maintaining the reputation of the brand and also adding a little innovation along the way.  He was certainly willing to spend some time on the phone with a guy who traded for an second hand gun made by the previous owner, and even sold me some parts in the process.  I wish them nothing but success and look forward to seeing how they do. 

[Wayne52]

Mike I know if I had one I'd probably be doing the same thing that you're doing, after all I doubt I'll go hunting the big big game, a white tail is fine for my purposes and that big bore would be much nicer than using a slug gun IMO.

[mackeral5]

What size is the hole the poppit is covering and what is OD of poppit?

How heavy is the hammer?

I included throat and stem diameters already.  Poppet OD is .375.

Hammer is heavier than 100 grams, maxed out my scale.  It is more than 150grams.  Maybe over 200.  Will be able to accurately measure  weight next week....

For now, I am starting very conservative and have increased throat to .375.  Waiting on some stem material to arrive this afternoon, then I will finish the peek poppet.....changes will be reversible, at least that is the intent for now.

The way the valve is constructed does not leave much room for throat increase without impacting the transfer port system. 

My goal is starting to become more clear, a few close shots of 400+fpe at high power, and a half dozen or more close shots above 300fpe for low power.  This is part 2 of why I am increasing throat size in small increments.  Part 1 is the desire to do all of this at a reduced hammer strike than the as delivered gun......

[mackeral5]

I managed to make some ground on this one. 

I replaced the ugly zinc fasteners.



I also managed to roughly fabricate a new valve stem with a peek poppet.  This reversed the factory valve setup which was Hatsan-like---steel valve with a plastic seat.
 I removed the factory delrin seat and created a valve seat on the aluminum valve body.  this moved the valve seat roughly .43" towards the transfer port....remember this as it will be come up again.  This method is also 100% reversible. 

I opened up the valve throat from .340ish to .375, which was a decent guesstimate as to where I need to be to achieve my goals.  Transfer is .375 and with the stem going through the throat, the throat is still the choke point. 

I messed up in calculating valve stem length and it ended up .45" too long....I forgot that I moved the seat rearward, decreasing stem length in the process, or at least that's what was supposed to happen.  I decided not to worry as this would simply reduce hammer throw a bit, and of course hammer strike which there is an abundance of already.  Here is a pic of the bolt at rest, those familiar with this gun will notice how far rearward the bolt is.  There is also a little more preload on the spring.  I don't know how all this averages out as compared to the original hammer strike with a .45 longer throw and less preload.  It doesn't really matter at this point anyway.



Aired up to 4500psi using the original heavy spring, here are some numbers:

302gr NSA
897
853
768 fps

254 NSA
959
906
833 fps

166 Hunter Supply
1098
1048
982
851 fps

Detuned a bit with a dual spring combo, starting at 4500psi.

254 NSA
860
904
866 fps

166 Hunter Supply
1003
1039
1017
974
917 fps


Shot cycle for the heavy spring became much more snappy until the 3rd shot.  Shot cycle with the dual spring was very snappy for practically every shot. 

I am liking results so far.  A spare hammer is going to arrive tomorrow, I look forward to doing some lighter hammer testing.  A faster moving lighter hammer is my favorite tuning tool, but I don't know how that will translate to a 400-500+fpe setup...

I am debating whether to open the valve throat any more.  There is still an abundance of hammer strike, plus I need to shorten the valve stem which will result in even more hammer strike. 

I have to keep reminding myself I only have 26.5 inches of barrel to work with....

While she was in pieces, I saw some striking similarities to tube/thread size.  check this out.  I do NOT plan to proceed any further than the mock-up you see below, but did want to share.  This is a Mrod tube extension and a WAR bottle adapter.  I can't recall if that is a 17 or 22ci bottle though.  The extreme tube is much thicker walled, but the ends match an Mrod.  There is a step just past the oring which tube ID gets smaller due to the thicker walls. 



Again, this is simply a mock-up that I do not plan to put together again.  This was for demonstration purposes only.

Looking forward to seeing any thoughts on throat diameter.....

[mackeral5]

here's some 3500psi data.  peek poppet, .375 throat.  Lighter twin spring setup, hammer barely preloaded.

166gr Hunter Supply
966
974
953
910

254 HSA
794
824
803

[Rizen 1]

Great job! You may want to try this for fine tuning..https://www.gatewaytoairguns.org/GTA/index.php?topic=85527.msg821213#msg821213

[Rizen 1]

This may also help...even though it was 40 cal testing, springs fit all calibers...

[Rizen 1]

The rva "rear velocity adjustment" should be an easy upgrade. Hope this helps...

[mackeral5]

Mike--thank you for joining the discussion.  Much of my research has included your Extreme posts.

I underestimated the effect of reducing hammer travel.  Last night I disassembled and did 2 things.  1, I cleaned up and radiused where I drilled out the throat.  I didnt do this before as I may have decided to go bigger in throat size.  At this time since I have a goal of 2 tunes, I dont plan to go any larger as I think that will negatively affect ES on low power tunes.  2, I trimmed the valve stem to a .55 stem protrusion, which is closer to OEM.  This restored hammer stroke to OEM.

Here are some initial results.  Heavy spring 4500psi start.

302 NSA
920
851
807

254 NSA
976
906
864

166 Hunters Supply
1128
1066
1018
984
940

I did some other testing but wont enter all of that data. 

I will be working on some type of RVA.....I think I have the porting in a good compromise between flow and restriction.  If high energy was my only goal I would go straight to .4125 throat, which is 10% over transfer size, something Bob S generally suggests and has worked well for me in other builds.

Time to work on hammer strike...

[rsterne]

Looks like you are closing in on it, Mike....

Bob

[mackeral5]

Looks like you are closing in on it, Mike....

Bob

Getting closer.  Have a couple more inner/outer springs coming so I can fine tune the combination.   Then I need to home in in a tune below max pressure, maybe in the 3800psi range.  Something I can shoot 3 shots, the top off with a guppie and repeat a time or two.  9 full power shots should satisfy any full day hunting scenario I can imagine.  I'm envisioning a full day of slaying nuisance swine somewhere nearby.

[mackeral5]

a Few pics...for anyone intimidated by making their own poppets, this should show you it isn't as hard as you think.  And you only have to be precise in certain areas.  This was carved from a piece of 1/2" peek rod and a m4 cap screw....

[rsterne]

Nice job!....

Bob

[Wayne52]

That PEEK is ideal using as a pcp poppet, I've never personally worked with it however I've got two that I bought from duy and the finish is mirror finish.  I have worked with delrin for transfer ports but haven't attempted making a poppet on the drill press yet.  I poked my thumbnail on one of the Peek poppet's and no give at all . . . it's hard stuff but sure makes a nice sealing surface.

[mackeral5]

Nice job!....

Bob

Thanks Bob.  Once I get 100% settled on porting I'll make a permanent poppet that is threaded on the striker end so the factory retainer will screw on.  This poppet  will fall out of the valve into the tune should it be pointed muzzle down and not pressurized. 

There is a side of me that wants to see if it can crack 600fpe by increasing throat to .4125.......but I'm pretty sure that will negatively impact having a second tune in the 300 range.

Can you share your thoughts on the matter?

This afternoon I cracked off a 166gr as the first shot of a 4500 fill.  This was the first time shooting it WFO  outside.  All previous full power shots were indoors over the chrony, wearing muffs.   It was LOUD.  I mean like PB loud.  I didnt shoot it anymore this afternoon, I wasnt quite prepared for that....

[mackeral5]

That PEEK is ideal using as a pcp poppet, I've never personally worked with it however I've got two that I bought from duy and the finish is mirror finish.  I have worked with delrin for transfer ports but haven't attempted making a poppet on the drill press yet.  I poked my thumbnail on one of the Peek poppet's and no give at all . . . it's hard stuff but sure makes a nice sealing surface.

Wayne, a good sharp file and as much RPM as you can get.  A fine hacksaw blade works for parting and for cutting oring grooves.  500, 800, 1200 W/D sandpaper to slick it up. 

For me the key is pressing/beating in the stem as the first operation.  A fairly tight interference fit.  You can add some loctite 638/680 before you press it in if it makes you feel better.  Then use the stem as an arbor.....

[mackeral5]

Working on the lower pressure, high power tune.  One of my optional inner springs arrived, it was a bust--coil bind right at barely cocking.  I may loose a coil or two and that will help.  Another size of outer springs will arrive tomorrow.

My current scale doesn't go beyond 100 grams so I can't get an exact hammer weight.  But with a not so precise fishing scale both hammers weigh at roughly 5oz.  I removed weight from one until it started reading in the 4oz range.  Soon I will have a more precise scale so that I can measure exact hammer weights.  I am thinking that  a 3500-3800psi tune is roughly 75-80% of 4500psi, so I plan to initially reduce hammer weight by 20-30%.

I found a combination of springs and the lightened hammer that gives a decent 3700psi tune.  With NSA 254gr, 3 shots goes 887, 887, 850.  Not quite my goal, but a decent tune nonetheless.  Fairly easy to cock, easier than the oem spring by far. 

I haven't been able to find the right combination of springs and pressure for a 220gr tune yet. 

[mackeral5]

Working on the lower pressure, high power tune.  One of my optional inner springs arrived, it was a bust--coil bind right at barely cocking.  I may loose a coil or two and that will help.  Another size of outer springs will arrive tomorrow.

My current scale doesn't go beyond 100 grams so I can't get an exact hammer weight.  But with a not so precise fishing scale both hammers weigh at roughly 5oz.  I removed weight from one until it started reading in the 4oz range.  Soon I will have a more precise scale so that I can measure exact hammer weights.  I am thinking that  a 3500-3800psi tune is roughly 75-80% of 4500psi, so I plan to initially reduce hammer weight by 20-30%.

I found a combination of springs and the lightened hammer that gives a decent 3700psi tune.  With NSA 254gr, 3 shots goes 887, 887, 850.  Not quite my goal, but a decent tune nonetheless.  Fairly easy to cock, easier than the oem spring by far. 

I haven't been able to find the right combination of springs and pressure for a 220gr tune yet.

I was able to weigh the hammers.

OEM hammer with cocking lever installed 182.6 grams

Lightened hammer/cocking lever in above 254gr tune 152.7 grams.  I think bullets 250ish and up I will run the full weight hammer and run the lightened hammer for 220gr and below. 

I've since trimmed it down to 145grams.   

Edging closer to the desired 220gr tune.  I stumbled across this tune starting at 3700psi 934, 936, 911