2240 bolt probe mod for velocity

howie1968 · February 16, 2013, 08:31:34 PM

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

quickster47 † · February 16, 2013, 08:54:52 PM

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

howie1968 · February 16, 2013, 08:59:51 PM

added link

quickster47 † · February 16, 2013, 09:16:22 PM

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

arkmaker † · February 16, 2013, 09:29:49 PM

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)

howie1968 · February 16, 2013, 09:32:40 PM

i was curious and wanted input before i attempt to modify, my longer barrel will be here next week

Gippeto · February 16, 2013, 09:43:35 PM

Video is by Kevin Mallard aka airsmith282.

Momma always said....

Oohhh.....the drama!

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

howie1968 · February 16, 2013, 10:04:04 PM

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

Gippeto · February 17, 2013, 12:05:24 AM

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

Al

howie1968 · February 17, 2013, 12:47:40 AM

Thanks mr gipetto, if i was to just buy an extended probe which one would you go with?

quickster47 † · February 17, 2013, 01:00:01 AM

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

howie1968 · 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

Gippeto · February 17, 2013, 01:27:05 AM

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

quickster47 † · February 17, 2013, 01:31:46 AM

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

Here is the link to his place: 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

cheewee · February 19, 2013, 05:32:41 AM

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.