Author Topic: Custom Bottle Mrod .25 build started (Read 20459 times))

miksatx · « **Reply #20 on:** May 20, 2015, 10:51:26 AM »

I'm curious what's the diameter on your bottle? How much gap between the bottom of the shroud and bottle?

PakProtector · « **Reply #21 on:** May 20, 2015, 08:51:08 PM »

Quote from: miksatx on May 20, 2015, 10:51:26 AM

I'm curious what's the diameter on your bottle? How much gap between the bottom of the shroud and bottle?

Bottles should be 2.375 and not stick up past the top of the air tube, so as much clearance as the OE has between the shroud and air tube.
cheers,
Douglas

miksatx · « **Reply #22 on:** May 20, 2015, 10:03:08 PM »

Douglas you think a 2.400 bottle would be ok?

Rdsail · « **Reply #23 on:** June 01, 2015, 08:44:08 PM »

My TJ .25 barrel finally came in. I still need to put the CF sleeve but tomorrow will be the big day. Power test!

PakProtector · « **Reply #24 on:** June 01, 2015, 09:17:55 PM »

Looks good to me...

Do you know if the 25's can be had in larger-than-1/2" OD? I am having some issue resisting the temptation to bore the barrel port to .5625 and run the barrel one size up. That is the plan for the B-Rod 30 cal anyway; that barrel starts at .590...skim it and see if it likes being bigger v. the 1/2 barrels.
cheers,
Douglas

oldpro · « **Reply #25 on:** June 01, 2015, 09:48:04 PM »

Right on!!! Let it rain.

Rdsail · « **Reply #26 on:** June 01, 2015, 10:15:53 PM »

I don't know if there are he has bigger OD barrels.

rsterne · « **Reply #27 on:** June 01, 2015, 11:13:52 PM »

You can get the .25 cal TJ's liners in 7/16", 1/2", or 9/16" OD.... The largest .30 cal is 0.590", and the largest .357 is 5/8"....

Bob

sixshootertexan · « **Reply #28 on:** June 01, 2015, 11:20:41 PM »

Can't wait to see the numbers Dan. Looking good.

Rdsail · « **Reply #29 on:** June 02, 2015, 10:54:04 AM »

First update: All shots made teathered at 2600psi

My first try I got 85fpe with 50g bullets but some issues came up. The first is that my tport is not sealing well. this is 50g going at 880fps The second issue was that I'm getting tons of hammer bounce. I went back and try to fix both things. I removed the extra weight on the hammer and made a stainless steel tport.

The second test. I got 94fpe with 50g bullets. I still have hammer bounce but very little in comparison and the Tport still leaks some air. The gun is very loud even with the 10" 1.5 dia LDC.

I should get more power if I up the fill pressure and I need to fix the tport. it will interesting to see when I try other bullets but I'm saving them for when I do the accuracy testing.

Tomg · « **Reply #30 on:** June 02, 2015, 11:16:50 AM »

Following!!

sixshootertexan · « **Reply #31 on:** June 02, 2015, 11:48:38 AM »

94fpe your almost there.

rjorge · « **Reply #32 on:** June 02, 2015, 12:00:06 PM »

Most likely one of 2 is going on:
-The air in front of the hammer is getting trapped.
-Too much air is escaping through the stem. I bet this is it.

Edit: I guess it could be TB blow by as well, which you are seeing.

Tomg · « **Reply #33 on:** June 02, 2015, 12:18:21 PM »

rjorge = Are you talking about the hammer bounce?

If you are, then no, hammer bounce is caused by the velocity of the return of the hammer compressing the spring and is pushed fwd again with enough force to knock open the valve again (repeatedly)
The way to fix it is what Daniel is already doing. Making the hammer lighter, reducing the pre-tension of the hammer spring(or making the spring super hard, but then hard to cock) increasing throw, or a combination of these to allow minimal bounce.

The right way of course is to have some sort of (slingshot) mechanism to take out the chance of the hammer re-compress the hammer spring on it's return. But this cost more and is more complex.

Rdsail · « **Reply #34 on:** June 02, 2015, 12:53:24 PM »

This is definitely air from the tport. It is coming from the sides of the breech. It's not that much which is good.

Tomg · « **Reply #35 on:** June 02, 2015, 12:57:12 PM »

I had that happening Daniel, I made a tport in brass, then chamfered the top, and made the same angle inverted recess on the receiving end (barrel or thimble) I.e. not a stepped one. Only using an O ring on the valve end of the t-port.

I am not sure how well that would work in your application (mine is the .22 - at 40+fpe)

rjorge · « **Reply #36 on:** June 02, 2015, 01:06:46 PM »

Tomg, yes I was talking about hammer bounce. If you haven't experienced any of those issues, they will most definitely cause excessive hammer bounce. A lighter hammer is only a band aid to the issue. I have experience both as well as many others here.

The blow by air causing the spring to compress even further after hitting the valve...

Btw, a hammer spring that "rattles" at 0 preload, slightly shorter, is the best cure for hammer bounce, outside of a mechanical brake.

Tomg · « **Reply #37 on:** June 02, 2015, 02:24:39 PM »

rjorge- I must apologize, I've never heard that those could cause hammer bounce.

shorty · « **Reply #38 on:** June 02, 2015, 04:59:29 PM »

I know this may sound crazy and possibly not work but, I'll throw it out there anyway ( just food for thought). On my .357 marauder build I find it difficult get larger than .18" on the transfer sleeve without a good seal due to the transfer port at the oring locations being so thin. It either bends from the pressure or assembly bends it.

So I have been kicking around the idea to eliminate the transfer sleeve completely by using an entire upper receiver to air tube gasket. Possibly a thin sheet of high pressure gasket material mated and punched to the dimensions of the both.

Rdsail · « **Reply #39 on:** June 02, 2015, 05:05:55 PM »

shorty,

I made my opening .303 instead of the .25 original. I have plenty of wall. I'm going to use PTFE tubbing and compress it some so it seals.

here is a picture with the CF tube over the barrel and LDC installed.

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Custom Bottle Mrod .25 build started

Author Topic: Custom Bottle Mrod .25 build started (Read 20459 times))