Oblong barrel port transfer sleeve?

[PakProtector]

hey-Hey!!!,
I want to try an oblong port in the barrel of my next build. I can see a few ways to go about it, but I have a few questions. Such as, should the valve's exhaust port spot face get lengthened so that the sleeve( likely TFE )gets smooshed between it and the barrel? I can see this as a block 1/2" long and 3/8" wide with a .250 round hole to match up with the valve and a .187 wide slot that is .115 between the centers to give me an area equivalent to the .25 bore at the barrel. How have y'all worked this out?
cheers,
Douglas

[rsterne]

The oblong transfer ports I have done are only oblong at the boreline, and round at the transfer port.... eg. in .25 cal, the port at the boreline is 3/16" x 5/16" and the transfer port is 1/4".... The back of the transfer port and barrel port line up vertically (and with the bolt face).... The front of the barrel port slopes about 30* forward from the front of the 1/4" transfer port to the 5/16" length required for equal area.... The transition on the sides of the barrel port from 1/4" wide to 3/16" wide is just a taper ground in by hand with a Dremel.... For a quarterbore I typically use a 3/8" OD Teflon transfer port with a 1/4" hole in it, and a 3/8" spot mill on the barrel and valve....

There is no reason your idea of a rectangular block for a transfer port won't work, just a bit harder to make, IMO.... If the barrel OD isn't wide enough to allow a 3/8" spot milled flat and still have enough meat left, it might be the way you have to go.... milling the flat on the barrel to 5/16" wide (with a 3/16" slot) and about 7/16" long....

Bob

[PakProtector]

Bob, I get the feeling a 1/2" OD barrel with a .224 or .250 groove diameter and chamber will support a 3/8" sleeve, yes? BTW, for the marauder, the sleeve is going to be between .500 and .520 long. I had worried about the thin sleeve walls, but IFF they are fit to the spotface ID and breech hole I think I will be OK. Sounds like it is time for a scale drawing to be sure I have everything properly laid out...lol and I wanted a new breech anyway for a probeless bolt. CAD to the rescue.
cheers,
Douglas

[rsterne]

Here's what I was suggesting....



A bit of a sharp edge where the 3/8" spot face meets the tapered front of the barrel port on the drawing, but you get the idea.... This way you can just make the transfer port from a piece of 3/8" round Teflon....

Bob

[SeanMP]

You could consider using a composite transfer tube. I have siezed brass and aluminum sleeves 0.010 wall inside PTFE

You could get a 0.250ID from a .312OD a be reasonably assured the walls would not collapse.

[PakProtector]

OK...this is first going to get done on a .22 The valve exhaust will be cut with a 5.5mm end mill at 20-degrees to vertical. Barrel port will be .265 long and .165 wide. Sleeve still from .375 Teflon round bar. The centers of the spot face on the valve( and the hole in the air tube ) and the breech and barrel will move forward .030" to avoid thin stuff around the breech sealing O-ring. Barrel spot face and breech sleeve hole to be cut at the same time for precise alignment. 1/2" barrel with a .224 bore will stand a .375 spot face according to Bob's drawing above.

TJ barrel is ordered, and Mike's check is in the mail....and now for some drawings...lol How to convince NOE to make me a 225107 mold quickly....hmmmm???
cheers,
Douglas

[rsterne]

.22 Hornet barrel (14" twist?).... That's what I used for my .224 Hayabusa for the 41 gr. RWS bullets we got from Drummen in Holland....

Bob

[PakProtector]

.22 Hornet barrel (14" twist?).... That's what I used for my .224 Hayabusa for the 41 gr. RWS bullets we got from Drummen in Holland....

Bob

that's the one...it will stabilize anything I can fit in a 25's magazine. I will have to get some of those Drummen pellets.
cheers,
Douglas

[willbird]

.22 Hornet barrel (14" twist?).... That's what I used for my .224 Hayabusa for the 41 gr. RWS bullets we got from Drummen in Holland....

Bob

that's the one...it will stabilize anything I can fit in a 25's magazine. I will have to get some of those Drummen pellets.
cheers,
Douglas

For just a few to try NAA sells a 30 grain for their cap and ball mini revolvers.....$8 for 250 of them.

http://northamericanarms.com/accessories/cb-accessories/cb-parts/cbb250.html

Cabelas has them too, and here is another source for 100 at a time.
http://www.impactguns.com/naa-22cal-30-gr-bullets-1-cbb-744253051272.aspx

[PakProtector]

I have a few of those left. Definately not suitable for 22 cal AG bores. This one should be fine with them. They are harder than the 2% tin I cast for the 25 cal though.
cheers,
Douglas

[willbird]

I have a few of those left. Definately not suitable for 22 cal AG bores. This one should be fine with them. They are harder than the 2% tin I cast for the 25 cal though.
cheers,
Douglas

I did not know you had tried them already, you and I are members of a select few that even know they exist :-). I wonder what the exact alloy is ??

Bill

[rsterne]

I'm thinking the NAA 30 gr. should be good for a .224 cal, no?....

Bob

[willbird]

I'm thinking the NAA 30 gr. should be good for a .224 cal, no?....

Bob

Actually .222 would be the best, 22 rimfire barrels are .222. Some early 22 hornets were as well. 1/16 would probably work great with that bullet...even slower maybe....they make a 1/20 for 22 short.

Bill

[rsterne]

TJ's make a .22 Short liner that is a 20" twist.... hmmmmmmmmmm....

Bob

[willbird]

TJ's make a .22 Short liner that is a 20" twist.... hmmmmmmmmmm....

Bob

Brownells has a Redmans too (they call it that anyway) and it is a buck cheaper than a 1/16 for some reason :-). Might be kind of fun to leave it 25" to start and see what that length will do :-).

[PakProtector]

I'm thinking the NAA 30 gr. should be good for a .224 cal, no?....

Bob

I plan to try them in the .224/.219, 14" barrel I have ordered. They are just under 3/8" long...and very close to .224, so they should work jus' fine. Get 'em trucking right along and they WILL punch through in a way that makes other pellets jealous.
cheers,
Douglas