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PostPosted: Wed Dec 16, 2015 12:34 pm 
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Joined: Thu Nov 02, 2006 4:57 pm
Posts: 1754
Location: mb
Quote:
I used a lathe to lighten mine by 50%....

You skillful and lucky Bastage! Mine look similar, but much, much uglier. The grinder works adequately, but it doesn't result in as clean and crisp lines
and contours as the one pictured.
I've only been able to shave 42-45ish% off of the several I've butchered. Thankfully its all good, and fortunately, the part doesn't "show" after final assembly. . .

I hammer a round wooden dowel into the spring seat on the back side of the striker, so I can chuck it up into a variable speed drill. Using the drill to turn
the workpiece as the grinding wheel carves the material off. Go slow, removing modest amounts of material with frequent cooling dips into a cup of
water. I did overheat one once that resulted in softening of the striker face, but heating and quenching appears to have re-hardened it suitable for
service. It's been in use for 7 or 8 years with no appreciable marring of the striker face or valve pin.

Good Luck!

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PostPosted: Thu Dec 17, 2015 10:06 am 
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Location: Greater Napanee, ON, Canada
BassmanSteve wrote:
I started work on legalizing my .177 conversion today.

This all started out with simply swapping parts between my 2240 and 1377. I kept the stock hammer spring, transfer port, etc. The only parts I used from the 1377 were the breech, bolt and barrel.

It shot very nicely with no further tweaking. It was a little quieter, grouped very well, pointed nicely, and felt better balanced with the longer barrel.

However, it was shooting well in excess of the PAL limit. With 8.2 gr RWS Meisterkugelns, and a fresh powerless, it peaked in excess of 550 fps.

My original chrony numbers were suspect, as I was having trouble sorting out the lighting for my new Caldwell chronograph.After about 30 test shots, I got the lighting sorted out, and it gave me a nice, consistent 5-shot string that looked like this: Average 526 fps, Standard Deviation 2.1, Min 524 fps, Max 529 fps, spread 5, TMV 526 fps

For obvious reasons (I don't have a PAL), I disassembled it after the initial test session.

Does anyone pay attention to this rule set out specifically by Webstien? There have been two blatant ones left on the open forum just this week.

topic43029.html

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PostPosted: Thu Dec 17, 2015 10:42 pm 
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Mac wrote:
Does anyone pay attention to this rule set out specifically by Webstien? There have been two blatant ones left on the open forum just this week.

topic43029.html

My apologies.

I figured that by documenting the process of de-tuning my 2240 and converting it from a .22 to a .177, I could elicit advice from more knowledgeable people along the way.

I immediately dis-assembled it after it shot over during the first test session, and it is now comfortably under the PAL limit.

Does this mean that I shouldn't have posted about my progress prior to getting it sorted it out?

If so, I invite the mods to delete my earlier posts, or the entire thread if necessary. It was not my intention to cause problems for the forum, or other people.


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PostPosted: Thu Dec 17, 2015 11:29 pm 
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Location: mb
Typically numbers recorded in excess of the limit, are generally reported as "too fast", or ">500", or more often, left unreported. . . .

It seems pretty clear that your intentions are true; I guess the concern would be the open information for someone who's intentions weren't, or the
implication that the forum is complicit in an illegal act. . .

I guess technically, you are providing damning testimony to your own trial. . . . :wink:

I'm sure the "staff" will amend it, if it's felt to be out of line, or if you ask really sweetly. Keep havin' fun!

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PostPosted: Sat Dec 19, 2015 6:39 pm 
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Since the 2240 was still rather loud, and sending visible puffs of C02 out of the .177 barrel with the power adjuster backed off for speeds in the low-mid 400's, I decided to turn down the hammer.

I could have done this after clipping the hammer spring, but I reasoned that since a lighter hammer would change the timing of the valve anyway, it might be better to make that change first. It's easy to cut length off a spring, hard to put it back on!

I had a head start, because mine is the late model, with a notch to clear the breech screw in tubes that are tapped for the "hidden" mount. I ended up following rsterne's pattern, and turning the hammer down all the way around. I estimate that I've probably reduced the hammer weight by about 40%.

I cut the hammer freehand with a bench grinder, so my workmanship is pretty rough in comparison to Rick's. Still, it's inside the tube, where I won't have to look at it again for a few years.

Internal friction should be reduced, since the hammer now rides on short rings of steel at front and back, instead of touching the wall of the tube over most of it's length. Regardless, I polished the contact areas.

While I was at it, I also shortened the rear grip screw so it won't interfere with the hammer spring or the adjuster again. Then I clipped the hammer spring a little shorter, oiled the spring seats, and buttoned everything up.

First impression:
- With the power adjuster still at 3.5 turns out, the report is much quieter, comparable to my 1377 oat 3 or 4 pumps,
- With less spring pressure behind the hammer, the trigger releases more smoothly.
- I suspect that I may be sub-400 fps at this point.
- Shot count on a fresh powerlet should be very good.

Chrony testing to follow...


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PostPosted: Sat Dec 19, 2015 11:45 pm 
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Location: Edmonton
Speaking from some experience (I was booted from the forum a few years ago for insisting that these types of discussions were perfectly legal and legitimate on an air gun forum), this rule was written at a time when there was a great deal of uncertainty as to the legality of modding air guns, especially to improve performance. Today, it is now pretty much universally accepted that these mods are perfectly legal, and the only concern is whether the modder has the credentials to possess the modified gun. Air pistols shooting over 500 fps are assumed to be just as legal as manufactured handguns, but they also fall under the same restrictions as manufactured handguns (e.g., RPAL and restricted shooting and transportation provisos).

My impression about this thread is that it is a discussion about complying with the law as opposed to breaking it: How to reduce the velocity of a handgun, in the process of modifying it, so that it remains at <500 upon completion. As we all know, the simple process of changing a barrel could put your air pistol over 500 fps "momentarily," until other parts are adjusted.


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PostPosted: Sun Dec 20, 2015 1:16 am 
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^^^
X2

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PostPosted: Sun Dec 20, 2015 9:20 am 
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Location: Greater Napanee, ON, Canada
What is legal and legitimate may not always be wise, Think about the political environment in Canada and what is good for the shooting sports and air gun community,

Maybe some respect for the rule that was written by the guy who created this forum is in order as well,

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PostPosted: Sun Dec 20, 2015 10:00 pm 
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Mac wrote:
What is legal and legitimate may not always be wise, Think about the political environment in Canada and what is good for the shooting sports and air gun community,

Maybe some respect for the rule that was written by the guy who created this forum is in order as well,


With all due respect to you, Mac, and the same respect to Weinstein and his mods, this rule has not been enforced for years. Modding is a common practice among air gunners these days, and is, indeed, the topic of many discussions on this forum. Whether the practice is wise is also a subject that this forum offers much information on, and it could not continue to advise people on what NOT to do if this subject had to go underground again.

The political environment sucks, but it certainly isn't going to get any better very soon. It think the last thing we should do is take our sport and hobby underground to avoid being seen by lawmakers. In fact, I think just the opposite, but I'll leave that topic for another time because I'd like to see this post remain in the thread.


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PostPosted: Sun Dec 20, 2015 11:27 pm 
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We seem to have gotten awfully off-thread, here.

I had intended this to be a tech post about what influences FPS variations on Crosman 2240's...


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PostPosted: Mon Dec 21, 2015 4:41 pm 
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Edmonton<500 wrote:
With all due respect to you, Mac, and the same respect to Weinstein and his mods, this rule has not been enforced for years.

I'll just say your "due respect" and mine differ. We'll agree to disagree on this subject. Webstien's thoughts on this would interest me.

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PostPosted: Tue Jan 05, 2016 6:12 pm 
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Joined: Tue Oct 13, 2009 1:27 am
Posts: 2514
Location: Vancouver
tazz wrote:
Do any of you guys have pictures of the 2240 hammer after you have ground half off.
I think it's time for me to save some gas and reduce the hammer weight. :idea:
Tazz


Thanks to Bob and his magical SSG (Stopped Spring Guide) temptation got the better of me today and I just couldn't resist any longer taking my 2240 carbine apart. De-gassed the HiPAC, broke everything down, and now I'm working on tapping the RVA (made by rrdstarr) out large enough such that I can readily swap out striker springs while experimenting, without having to take the gun apart again just for that. While it was open I remembered to photograph the striker/hammer and to weigh it.

Seems I didn't take off as much steel as I'd guessed; it still weighs 48 grams (checked on a decent kitchen scale then on my triple-beam balance), a stock one apparently weighing 60 grams though I can't find much confirmation on that. Huh, thought it was lighter. Oh well, it's working for me. Now I'm eager to see if I can duplicate some of Bob's borderline miraculous increase in efficiency with this bound, pre-tensioned, lighter and longer hammer spring, lengthening my shot string yet further between fills. Here's my striker on a diet:

Image

Now I'll get back to my last modification of the 2240.... no, really...


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PostPosted: Tue Jan 05, 2016 6:39 pm 
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GerardSamija wrote:
a stock one apparently weighing 60 grams though I can't find much confirmation on that.


Confirmed: 59.97g on a Hornady digital powder measure scale.

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PostPosted: Tue Jan 05, 2016 9:08 pm 
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Location: Edmonton
GerardSamija wrote:
18 hours to grind down a Crosman striker? Huh, wouldn't have thought that possible, but I guess I've met the odd person like that. For mine it took about half an hour and two Dremel 3/4" grindstones. Which aren't cheap, but gave me better control than my bench grinder. I wore a good mask, silicone rubber with fine particle filters, as it's really not healthy breathing all that carborundum dust from the fast-shrinking grindstones. The Crosman strikers are case hardened. That makes use of a mill rather a difficult proposition, as high speed steel cutters will just chip and fall apart hitting the outer surface. A carbide cutter taken in very slowly might work but I wouldn't want to try in case it just shattered. Grinding seemed the obvious route. Once through the case hardened later it's just mild steel, easy enough to carve.

Using a lathe would be problematic as it would probably impact sear function with the 2240. I left the upper and lower edges of my striker alone, only removed steel from the sides, rather deeply, cutting almost to the spring hole. Asymmetric carving like that is a job for a Dremel. Just take small passes at first, little bites, until you get into the rhythm of it. Mark out your planned area of stock removal with a Sharpie and think about just getting up to those lines, no further. Think about the direction a grinding wheel wants to climb in the cut, so you know what to expect when the Dremel tries to run away from you and grind something you didn't want ground. Starting in the middle of the marked area is best, working your hollow outward in both directions smoothly so you're enlarging the hollow, not creating ripples which can make for difficulty as the grinder hits them.


Excellent advice for the inexperienced, Gerard (that would be me, and many others, I suspect).


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PostPosted: Tue Jan 05, 2016 10:03 pm 
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Location: Coalmont BC
As I mentioned above, the profile of the bottom is only important if you upgrade to a PRod trigger.... and in fact a stock 22XX hammer won't work with that trigger.... You can cut away all of the middle, leaving only the front and back on the bottom and it will still work fine with a 2240 or 2260 trigger....

Bob

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