i just watched a video of a guy doing a boltprob mod, this increased velocity quit a bit. he was saying to reduce the diameter of the probe by 1.2, he showed a video of how it doesnt restrict the air as much. what do you all think? or is there more info on this. i also have the long steel breech and my 14.5 inch barrel will be here next week
http://wn.com/How_To_Mod_A_Crosman_2240#/videos (http://wn.com/How_To_Mod_A_Crosman_2240#/videos)
How about supplying us with a video link so that we may peruse the video and draw a conclusion.
Last year I played around with completely doing away with the probe and the results were abysmal to say the least. Nothing like I was expecting.
On most of my extended probes I use 0.062 wire and have good luck, but I don't think there was any significant gain in FPS.
Carl
added link
Well that was interesting but I have some doubts. It would have been better if he would have done some chrony testing using the box stock gun then do the probe modification and some more chrony testing to provide some hard numbers.
Carl
While it can be argued, 10 fps gain is the general consensus for a hollow or extended probe. Best things or better things to consider are easier pellet seating and seating the pellet deeper onto the rifled part of the barrel.
Just my 3 cents worth (inflation)
i was curious and wanted input before i attempt to modify, my longer barrel will be here next week
Video is by Kevin Mallard aka airsmith282.
Momma always said.... :-X
Oohhh.....the drama! ;D
Different pellets have different skirts....hollow probe pushes all of them to the same point past the transfer port. Standard probe may leave some skirt designs partially covering the transfer port...pellet damage may be a result. Extended probes push the pellet past the TP, but still to varying depths.
Personal preference is a hollow probe on a target oriented airgun, extended probe on the rest.
For .22 cal extended probe, I make 'em .320" length x .100" diameter.
Al
Mr gippetto, im just going to punch some paper some cans and maybe a bunny or two. accuracy is what im after, i mainly use crosman 14.3 hollowpoints as they are readily available. which would you recomend for my application i will be adding a 14.5 inch barrel next week
Doesn't sound like an "all out" 10m effort to me...would extend the probe.
Some reading for ya...a few good links at the end of the thread too. ;)
http://www.network54.com/Forum/275684/thread/1257693777/Extended+probe+bolt+questions (http://www.network54.com/Forum/275684/thread/1257693777/Extended+probe+bolt+questions)
Al
Thanks mr gipetto, if i was to just buy an extended probe which one would you go with?
GMAC or Mellon Air are two that come quickly to mind, and I'm sure there are others.
But you know you can also make your own.
Carl
thanks Carl ill look into that. im not much of a tinkerer i know getting into this hobby it is beneficial to tinker or build your own id almost rather buy a tried and true product drop it in and shoot, i realize that sounds lazy but i cant seem to get enough pellets down range since this addiction took place a few months back, ive bought 9 airguns and no plan on stopping
Quote from: quickster47 on February 17, 2013, 01:00:01 AMBut you know you can also make your own.
I would like to encourage you to try your hand at it. Time was, this was how modding was done...very few folks purchased parts because they simply weren't available to purchase. I know "stroking a cheque" is easier than "doing", but I don't find it nearly as rewarding on a personal level.
Have a go at it...might surprise yourself. :)
Al
Quote from: howie1968 on February 17, 2013, 01:20:38 AM
thanks Carl ill look into that. im not much of a tinkerer i know getting into this hobby it is beneficial to tinker or build your own id almost rather buy a tried and true product drop it in and shoot, i realize that sounds lazy but i cant seem to get enough pellets down range since this addiction took place a few months back, ive bought 9 airguns and no plan on stopping
Definitely sounds like you are hooked, and the sad things is there just ain't no cure for Crosmanitis.
GMAC makes good stuff but coming from the UK it can be slow on the delivery. Charles Mellon also makes fantastic pieces but right now he is also swamped so it might take several weeks to get parts from him.
Here is the GMAC link: http://www.gmaccustomparts.com/epages/BT3197.sf/en_GB/?ObjectID=6425643&Category=10181900 (http://www.gmaccustomparts.com/epages/BT3197.sf/en_GB/?ObjectID=6425643&Category=10181900)
Here is the link to his place: http://mellonair.com/index.php?p=1_7_Crosman-Bolts (http://mellonair.com/index.php?p=1_7_Crosman-Bolts)
If all else fails I can modify an OEM bolt for you making it an extended probe. Will cost you $10 plus shipping. But I guess I should check and see if I have some OEM bolts in stock.
Carl
did a test with six probes on sunday and had some interesting results. all the probes came from different sources and they were all machined a little different,
some were longer some were smaller dia. and one flow thru had oversized hole compared to the specs i have. was surprised to find a 70fps variation over the 6 of them with 5 of them being within 40fps which left me with 1 clear loser. will not go into specifics because what works for me may not work for you but i definately have my two favorites now. this was in no way a comprehensive test and there are way to many variables to be able to draw any concrete conclusions, just saying it pays to experiment.
LOL Jeff atleast ell us was it a extended prob or a flow through that was your Pick.... no need to say who made them :)
Quote from: cheewee on February 19, 2013, 05:32:41 AM
some were longer some were smaller dia. and one flow thru had oversized hole compared to the specs i have. was surprised to find a 70fps variation over the 6 of them with 5 of them being within 40fps which left me with 1 clear loser. will not go into specifics because what works for me may not work for you but i definately have my two favorites now. this was in no way a comprehensive test and there are way to many variables to be able to draw any concrete conclusions, just saying it pays to experiment.
Your results are not surprising and truthfully what I feel everyone experiences.
As always with some many parts, "Your Mileage May Vary".
Carl
I have the origiganl bolt that came with the plastic bolt, let me ask this if i was to reduce the diameter of the probe on my steel bolt with my steel breech kit how would i do this? with a dremel and roll it to make it even. i havent progresed to even tamper with valve work but if i can gain some by going to the 14.5 inch barrel then do a probe mod and increse velovity some, as stated im basically going to shoot paper and cans but like the idea of popping a rabbit. i want as much energy as i can muster without getting into the valves just yet, i feel another 2240 will be ordered soon
^^^ It could be done with a Dremel albeit I am not sure exactly how true it would turn out but the absolute best way would be to use a lathe. However, being that you may not have a lathe or access to one, there are many here on this forum that have had exceptionally good luck chucking something like the bolt in a variable speed drill and doing something like what you are proposing. Just take your time and be in no hurry.
BTW, your original brass bolt that came with the plastic breech would have to be taken apart and the cocking handle removed and then the bolt tapped to 8-32 to accept the handle. The brass bolt and handle are staked together from the factory.
Carl
IMO, the research done by so many folks on this forum, shows modest velocity gains at best. For me, the most important attributes of the extended probe are air-flow (as Carl noted) and a really good o-ring seal on the probe. A good seal, with the pellet pushed past the transfer port makes the "lock time" slightly quicker or more efficient with less chance of pellet damage or scrapes on the head or skirt when loading. All good stuff in the quest for repeatability which adds to overall accuracy and efficiency of the gun.
I believe Charles Mellon agrees with this concept, as his webpage for the extended probes (choose hollow or solid types) basically states (my paraphrase) don't ask me which style is better, buy them both if you are that anal about it. :D :-*
I remember seeing a video where they cut the bolt off froward of the o ring, then drilled and inserted a piece of music wire. This way you could also extend the probe.
Yea, I saw some russian dude make a video and he took apart a lighter, I guess just for the o-ring, and put that on the bolt probe. Then he drilled it out and glued some piano wire in there. I had no idea what purpose that served when I was watching it, but now it all makes sense.
Quote from: DaveB50 on February 19, 2013, 06:50:10 PM
I remember seeing a video where they cut the bolt off froward of the o ring, then drilled and inserted a piece of music wire. This way you could also extend the probe.
Well, I never made a video of mine :P, but that's how I did it too. Instead of music wire though, I used (are you ready for this?) - S/S finishing nails! :o. Before you ask, "Why finishing nails"?... short answer is "Because that's all I had on hand at the time that would work"! Keep in mind the only tools I had at my disposal was a cheap drill press, a Dremel and some files/sandpaper! :-[
"Skinny" probe on left is from a 1-1/4" nail. Shank is 1/16" diameter (made for a nice, snug fit in bolt), head of nail was 3/32". The fatter probe on the right is made from the shank of a 2-1/2" nail, which was the same diameter as the "head" of the first one (3/32").
(http://i1100.photobucket.com/albums/g401/windrifle/extendedprobe002.jpg)
Both probes were cut 5/8" long, 3/8" of which is inserted into a 1/16" hole drilled in end of bolt which gave me a finished bolt length of 1-7/8" - just barely enough room to still load Polymag's and still have the skirt completely ahead of TP:
(http://i1100.photobucket.com/albums/g401/windrifle/extendedprobe006.jpg)
(http://i1100.photobucket.com/albums/g401/windrifle/extendedprobe007.jpg)
:-*
Todd
Good job Todd. :-* :-* :-* As they say, necessity is the mother of invention. :)
Carl
Cool Todd!
Quote from: agninja on February 19, 2013, 08:14:43 PM
Yea, I saw some russian dude make a video and he took apart a lighter, I guess just for the o-ring, and put that on the bolt probe. Then he drilled it out and glued some piano wire in there. I had no idea what purpose that served when I was watching it, but now it all makes sense.
I also saw that same video and was pretty impressed with the kid's ability to do this-and-that... :-*
Good looking bolts there Todd.
Quote from: MichaelM on February 19, 2013, 07:22:04 AM
LOL Jeff atleast ell us was it a extended prob or a flow through that was your Pick.... no need to say who made them :)
the probes that performed the best were both extended probes with dia. slightly smaller that what i consider to be the norm.
I read but don't remember where that its tough to get the flow-thru to beat
the extended until you get to .22 and above......
tough to pull the breech on a good build just to test stuff ....nice work cheewee :-*
Quote from: WyoMan on February 20, 2013, 03:33:32 AM
I read but don't remember where that its tough to get the flow-thru to beat
the extended until you get to .22 and above......
tough to pull the breech on a good build just to test stuff ....nice work cheewee :-*
This is also what I have come to understand from research.... (I personaly have not gotten there yet but my thoughts and experiance with other things would have me tending to lean in this direction as well) the opening is just to restrictive no matter how big you get it in .177(and alot of time have decreases in speed) and in .22 its really toss up as they both seem to be about equel.... seams the real gains start in the .25 and up as far as power+ consistancy goes.... where there is enough meat on the prob you can open it way up and have plenty of flow.....
think I will try to experiment with both 1/8 and 1/16 drill rod.... and maybe smaller if 1/16 seems to be beefy enough to stand up to the abuse.....
And Thanks Jeff for going through the pain of pulling your girl apart and putting her back together to test this out for us!!!!
sure is a pain changing probes but at least i know my modified t.p and beefed up breech screw are good to go, gotta love a breech screw which uses a 1/16 allen key the original .050" sure would not have done it.
Quote from: WyoMan on February 20, 2013, 03:33:32 AM
... its tough to get the flow-thru to beat
the extended until you get to .22 and above.....
I realize it pretty much boils down to individual preferance, but even in .22 or .25 I would stick with extended over flow-thru. The following is a post by Rsterne with definitive results on the matter. Yes, it's on a QB, but the principals are the same for all you "power-monger's" (myself included) looking to squeeze every bit of fps you can get:
Quote from: Rsterne
Well I did a VERY interesting test today.... There is an ongoing argument about which is better, flow-through style bolts or ones with an extended probe that seat the pellet skirt just past the transfer port.... I've been favouring the probe style, but today I got to finally prove it.... I chucked the .22 cal QB bolt in the lathe, and machined off the front of the flow-through section, back to the rear edge of the transfer port hole.... I then drilled a 1/16" hole down about 1/4" past the O-ring groove and fitted in a piece of 1/16" music wire of the appropriate length.... I fitted a sleeve over the wire made from 3/32" OD x 1/16" ID - K & S brass tubing from a hobby shop.... I adjusted the lengths until the probe was 0.100" longer than the front of the original bolt to make sure that any pellet would be seated with the skirt clear of the front of the transfer port.... A couple of drops of crazy glue (plus a good fit) hold the pin and sleeve in place....
I stripped off the .177 cal barrel and bolt, and installed the .22 barrel and the now probed bolt and proceeded with Chrony testing.... I used the 18.1 gr. JSB Exact Heavy pellets which the gun particularly liked.... Here are the before and after numbers....
Number.......... Flow-Through...... Probed
Avg. Velocity......871 fps...............903 fps
Avg. Energy.......30.5 FPE..............32.8 FPE
No. Shots..........40........................37
Total Energy......1220 FPE.............1214 FPE
Efficiency...........0.85 FPE/CI.........0.85 FPE/CI
The probed bolt.... with NO other changes from the flow-through bolt.... increased the velocity by 32 fps and the energy by 2.3 FPE (7.5%).... The total energy per fill remained the same, which reduced the shot count by three shots.... There is no longer any question in my mind that a probed bolt is superior to a flow-through style in terms of performance.... at least in a higher powered PCP.... Just to double check, I also tested the RWS 11.9 gr. Hobbies, and the EunJin 32.1 gr. Pointed pellets.... the Hobbies gained 35 fps (1.9 FPE) and the EJ Points gained 20 fps (2.0 FPE).... so the results are not limited to the JSB pellets....
Besides, this is one of my (purchased) flow-thru bolts after only 200 shots >:(. I never had this problem with any extended probes I ever made... ;)
(http://i1100.photobucket.com/albums/g401/windrifle/HollowProbe001.jpg)
(http://i1100.photobucket.com/albums/g401/windrifle/HollowProbe006.jpg)
Cheers,
Todd
Did you contact GMAC about replacing that probe?
Carl
you could always go with this design. you will not see any boost in fps, but seating the pellet is a charm.
Quote from: quickster47 on February 20, 2013, 01:34:48 PM
Did you contact GMAC about replacing that probe?
Carl
Not directly. I contacted the Canadian vendor where I purchased it, who in turn contacted GMAC. Apparently it wasn't an isolated incident as both GMAC and vendor have had a few cases where this has happened. Turns out it was a combination of probe being bored just a hair to deep, not leaving enough meat between probe/o-ring groove, and probe diameter being a whisker to big (.217") which made for a (too) snug of a fit when closing the bolt. I guess the fabricator was having an "off day" ???
Really wasn't a big deal for me though. Had an extra flow-thru and it's fine. Besides, it gave me a chance to try making an extended probe bolt, and I haven't looked back since! ;D
Todd
Quote from: arkmaker on February 20, 2013, 02:05:34 PM
you could always go with this design. you will not see any boost in fps, but seating the pellet is a charm.
I remember following that thread quite closely. Great job!
Seems to me like you get the best of both world's with that design :-* :-* :-*
Todd
Thank you all for the great input!! thois type of discussion was exactly what i was looking for once again thanks
one more thing howie or three (if you ever use flow-thru)
flow-thru bolts should just barely clear the transfer port in length or there will be too much transfer volume
the port in the flow thru should be checked for alignment with the TP
the ID of the flow-thru can be enlarged (helpful with smaller bore)
Here's a pic of one I modified for .22:
(http://i1249.photobucket.com/albums/hh508/WyoMan/flowthrubolt.jpg)
notice how much I cut from the end from the other GMAC bolt
Good info Wyoming... and you indexed the hole on one side only? Nice.. :-*
You be right Brian, had to index the port a little some of it because I openned up the TP a little - thanks :)
the ID of the flow-thru can be enlarged (helpful with smaller bore)
I don't understand this ?
Quote from: KevinP on February 21, 2013, 12:08:07 AM
the ID of the flow-thru can be enlarged (helpful with smaller bore)
I don't understand this ?
Perchance he was referring to them .177 probes/barrels Mr. K..
smaller bore but meant smaller caliber...
this keyboard shows what I type instead of what I meant ;D
the smaller caliber bolts with the same wall thickness as the larger ones have less opening vs bore diameter
so there is more flow restriction unless you make the wall thinner
as the diameter increases you don't have as much of a problem with the larger caliber
Thanks,
Ahhh thanks ... :-*
I took a stainless extended probe and put it in my cordless drill, and used a file to turn it down some. I felt the tip mushroomed out too much. Cheewee, care to elaborate a little bit on your non .050 breech screw?