Got my long steel breech from Crosman yesterday. To my surprise the breech screw hole was in the front ??? Anticipating the rear screw hole, I had modded my hammer (cut a notch) :-X Oh well...No big deal. I thought that the Crosman steel breeches had the rear screw hole. Did I miss something here ???
Was the new breech for the 1377 series of guns? ???
If I remember correctly the 1377 main tubes do not have the second hole drilled and tapped for the rear breech screw.
Carl
I thought only the custom shop guns get the breech with the rear hole and maybe the disco but it doesn't heve the dovetail notch cut into it. Gets more confusing all the time.
It was the 2240 kit. I would think the front screw hole would make a better seal between TP and barrel ???
Quote from: bgmcgee on February 15, 2014, 02:33:43 PM
I thought only the custom shop guns get the breech with the rear hole and maybe the disco but it doesn't heve the dovetail notch cut into it. Gets more confusing all the time.
I believe you are correct as my .177 cal steel breech kit also had the front hole, but my 2400KT had the rear hole.
Quote from: AS13 on February 15, 2014, 03:19:12 PM
It was the 2240 kit. I would think the front screw hole would make a better seal between TP and barrel ???
I feel the same. The big plus with the rear screw is a smooth transition to load the pellet especially .177.
Quote from: vertguy on February 15, 2014, 03:33:27 PM
I believe you are correct as my .177 cal steel breech kit also had the front hole, but my 2400KT had the rear hole.
Same here...My 2400KT had rear breech screw ???
Quote from: AS13 on February 15, 2014, 12:51:22 PM
Got my long steel breech from Crosman yesterday. To my surprise the breech screw hole was in the front ??? Anticipating the rear screw hole, I had modded my hammer (cut a notch) :-X Oh well...No big deal. I thought that the Crosman steel breeches had the rear screw hole. Did I miss something here ???
I have purchased 4 steel breeches over the past year. 2 kits directly from Crosman and 2 steel breech only from a Crosman authorized dealer. ALL of them had the "front" breech hole configuration. It might be that you have to ask specifically for the "rear" breech screw hole configuration to get that type. Flex
A guy at GTA just went through the breech types and after getting the wrong one did get the correct part #s.
Long steel breech w/rear screw location: AS2250-025
Long steel breech w/front screw location: AS2250-A013
The 22xx tubes have both front & rear screw holes in the tube. The 13xx tubes have only the front screw hole.
Its cheaper to order just the breech and needed parts from Crosman than to order the breech kit.
Newly manufactured non-CCS tubes that are built into guns and sold usually have tubes with BOTH holes. But the factory tubes by themselves are mostly of the front hole variety. At some point I would expect all replacement tubes to have both holes all the time.
This situation actually causes me grief in that breeches would not be served well with both locations, so that adds another variation to the complexity of the possible.
When you read somebody wondering why Crosman doesn't do this and that, this is the reason why. It get WAY out of hand REAL FAST!
Just with Crosman steel breeches we already have short and long, and breech screw fore or aft... so that is four possible versions.
Now lets add LH, RH and ambidextrous to the above and we are up to 12 versions. :-[
Then add blued steel, aluminum anodized, brass and stainless. We are at 48 versions. >:(
Want a choice between dovetail and Weaver/Picatinny? Now we have 96 versions. :(
Provisions for LPA MIM or a standard rear sight or nothing (for optics only) and we have 288 possibilities! :o
All of the above a major design machined differences with no opportunities for either/or. Variation / complexity sucks on the manufacturing end, but we do love to have our choices, don't we? ;)
My 2400KT has the rear breech screw and the two tapped tube holes, which led me to a thought. I may be alone on this idea, maybe not. On both the 13xx and 22xx have the tubes tapped with front and rear holes AND have both screw holes in the breech. An extra strong breech mounting, an extra hole in case one gets stripped. Just a thought.
I built the .177 Beast from a 2240...front breech screw. Since it is atop a BnA riser it has the longer breech screw, a slotted screw. Pellet hang-ups were driving me nuts so I used a diamond ball bit in the Dremel and made a "feed ramp" on the forward edge of the screw hole. Pellets don't get hung near as often.
I experienced this recently when I tried to put the steel breech from the ccs (rear location) onto a 1322 (front). I drilled the front hole in the breech only to realize that it wouldn't work (no recessed space for the screw head). Do I have to drill & tap a hole at the rear location? Or just drill a hole (and if so, any idea what bit to use)?
fasteddy, the correct tap drill for a 4-48 screw is #40 for steel.
Quote from: fasteddy on April 08, 2014, 05:51:37 AM
I experienced this recently when I tried to put the steel breech from the ccs (rear location) onto a 1322 (front). I drilled the front hole in the breech only to realize that it wouldn't work (no recessed space for the screw head). Do I have to drill & tap a hole at the rear location? Or just drill a hole (and if so, any idea what bit to use)?
countersink it with either an end mill or a drill bit
If I tap it, I will use probably use a 4-40 and get a new screw. It just seems like the tube wall is so thin that there isn't much room to draw threads on it.
When I looked at the front hole I drilled, it lined up, but there didn't look like there was enough headroom between the front of the hole and the top of the breech to fit any kind of countersink bit (and I'd have to buy one for steel anyways).
fasteddy you cannot simply re-tap a 4-48 hole to a 4-40. The tap hole for a 4-48 uses a #40 tap drill, a tap hole for 4-40 uses a #41 tap drill. The higher the drill # the smaller the diameter it is. If you try to re-tap the 4-48 hole to 4-40 you will only get 25% or less thread engagement...not nearly enough meat on the threads to hold down a breech. I know from personal experience on this one, it simply will not work....sorry.
If you have a means to accurately re-drill the holes and tap (breech and tube) you could step-up to 5-40.
http://www.engineershandbook.com/Tables/taphole.htm (http://www.engineershandbook.com/Tables/taphole.htm)
This is the guide I have always used for any drill and tap application I have, be it Delrin, aluminum, brass, stainless or mild steel. It gives all drills needed for each tap size plus the drills required for close and lose clearance holes. I have many copies of this chart that I keep all around my shop...in note books, on clip boards, etc.
On the left it give the major and minor thread diameter for each thread. If you notice, any tap that is used for very fine threads uses a drill size very close to the minor thread dimension. Fine threads are VERY shallow. Course threads are, of course, deeper so a smaller drill would be used to allow for the cutting of the deeper threads.
Believe it or not, on my Crosmods breeched 1377 (my very first mod) I kept stripping holes from over-torque because I was trying to get too much of a compression fit on the long transfer tube. I ended up at 8-32 and it has held tight for a very long time...I just don't torque as much now!! ;D
Quote from: fasteddy on April 08, 2014, 12:56:25 PM
If I tap it, I will use probably use a 4-40 and get a new screw. It just seems like the tube wall is so thin that there isn't much room to draw threads on it.
When I looked at the front hole I drilled, it lined up, but there didn't look like there was enough headroom between the front of the hole and the top of the breech to fit any kind of countersink bit (and I'd have to buy one for steel anyways).
use a drill bit slightly larger than the screw head to countersink the hole
Quote from: airriflenut on April 08, 2014, 01:13:58 PM
fasteddy you cannot simply re-tap a 4-48 hole to a 4-40. The tap hole for a 4-48 uses a #40 tap drill, a tap hole for 4-40 uses a #41 tap drill. The higher the drill # the smaller the diameter it is. If you try to re-tap the 4-48 hole to 4-40 you will only get 25% or less thread engagement...not nearly enough meat on the threads to hold down a breech. I know from personal experience on this one, it simply will not work....sorry.
If you have a means to accurately re-drill the holes and tap (breech and tube) you could step-up to 5-40.
There is no hole... that is the problem. I'm having to drill a hole in the tube to match the rear screw location on the breech, hence I am starting my own hole. The diameter of the breech hole is 4, so I can use 4-40 on the tube, but what I was concerned with is that upon drilling a hole in the tube, I wasn't sure whether I could successfully draw threads on the wall as they are so thin... but Crosman did it... and I'm sure you guys have... so I will give it a shot!
Quote from: rws_53 on April 08, 2014, 01:45:15 PM
use a drill bit slightly larger than the screw head to countersink the hole
I could try that. I did find, however, that the bits I already owned were not making much of a dent in the steel breech. I had to go out and buy a tungsten bit to make the front hole.
Quote from: fasteddy on April 08, 2014, 08:23:01 PM
There is no hole... that is the problem. I'm having to drill a hole in the tube to match the rear screw location on the breech, hence I am starting my own hole. The diameter of the breech hole is 4, so I can use 4-40 on the tube, but what I was concerned with is that upon drilling a hole in the tube, I wasn't sure whether I could successfully draw threads on the wall as they are so thin... but Crosman did it... and I'm sure you guys have... so I will give it a shot!
If you go with a rear hole screw your hammer would have to be modified to clear the screw.
Quote from: rws_53 on April 08, 2014, 08:32:04 PM
If you go with a rear hole screw your hammer would have to be modified to clear the screw.
The plot thickens! I'm glad you guys are around to warn me about these things! Now I'm back to thinking I should work on the countersink!
I'll have to buy a larger tungsten bit for it... maybe I can return the single bit I bought and buy a kit...
Can I first run another idea by... so you can tell me it is silly and prevent me from trying... is there any way I could try to 'freestyle' a countersink by using a dremel bit? I have a couple pointed cutters that carve steel up no problem... it wouldn't be a perfect circle, but it could at least get the job done. Probably a bad idea, right?
Quote from: fasteddy on April 09, 2014, 02:26:23 AM
The plot thickens! I'm glad you guys are around to warn me about these things! Now I'm back to thinking I should work on the countersink!
I'll have to buy a larger tungsten bit for it... maybe I can return the single bit I bought and buy a kit...
Can I first run another idea by... so you can tell me it is silly and prevent me from trying... is there any way I could try to 'freestyle' a countersink by using a dremel bit? I have a couple pointed cutters that carve steel up no problem... it wouldn't be a perfect circle, but it could at least get the job done. Probably a bad idea, right?
I did mine on a small Sherline vertical mill using a drill bit to do the hole then an end mill to countersink it. Do you have a drill press and a way to clamp the work to the table for your Dremel? Likewise using a drill bit...you'd want to use a drill press and clamp the work down. Freehand could get pretty sloppy.
If you have a drill press, even a bench top press, you can get an inexpensive cross slide vise to bolt on the press table. I've got an old Sear bench top my dad gave me a few years back, don't remember any h.p. or such but it's built like a tank.
I got a cheap cross slide (I do mean cheap, about $49) and I use it frequently. The main thing I don't like about it is that one side of the vise jaws has a slot under the jaw face, I cannot use any parallels due to that. Something to check for if you go that route.
When I buit my bulk feed Beast I made many of my own parts using only the bench drill press with cross slide, a bench top band saw and a Jet 1014VSI wood lathe.
Good luck and keep if posted.
Jees guys... I'm way more of a luddite than all of that. All I'm working with is a dremel and and a cordless drill. That is all...
:-[
I drilled the hole in the breech from above with the breech lying on the work bench. I can clamp it down, if that helps, but that is about it. I feel like it will be fine, though, as the hole doesn't have to be perfect... it just needs enough room for the screw head to clear. Hell, if it is more shallow than stock, it will probably function better (won't give enough depth for the pellet to fall face-down into!).
Quote from: fasteddy on April 09, 2014, 08:25:32 PM
Jees guys... I'm way more of a luddite than all of that. All I'm working with is a dremel and and a cordless drill. That is all...
:-[
I drilled the hole in the breech from above with the breech lying on the work bench. I can clamp it down, if that helps, but that is about it. I feel like it will be fine, though, as the hole doesn't have to be perfect... it just needs enough room for the screw head to clear. Hell, if it is more shallow than stock, it will probably function better (won't give enough depth for the pellet to fall face-down into!).
You are not alone there. And mine isn't even a real Dremel, it's a bottom of the line Harbor Freight cheapy with one speed. :(
If you guys need a rotary tool and don't want to pay the Dremel price or settle for the HF cheapo check out northern Tool. The have a single tool package, I got one, that comes with a lot of attachments, even a clamp hangar for the tool if you want to use the INCLUDED flexible shaft. I think i gave around $39 a couple of years ago. Awesome tool for the price.
They also have a two tool package, the regular variable speed 120v and a small palm size 12v single speed. The small one is excellent for polishing the barrel leade, bolt race, etc. It come with even more attachments AND the flex shaft with clamp on hangar. Around $69 if memory serves me. Both a much better deal than Dremel offers.
Just an FYI...sorry for the hijack. :)