Author Topic: Prod upgraded! (Read 30059 times))

DeutschKSK · « **Reply #40 on:** October 04, 2011, 11:06:13 AM »

Quote from: RatRacer on October 04, 2011, 11:03:54 AM

Quote from: darryl on October 04, 2011, 12:00:23 AM
OK, I found the fill cap. It's accurate to say it was under the last place I looked. I took some shots at 30 yards today, and the accuracy is not there. I've gone through several magazines now, so maybe it's time for a good cleaning. At 9.5 yards the accuracy is quite good, though.

Also, need a little science here. How does the longer barrel make the P-rod louder? As you can see in the one picture, the shroud is on. I would have thought the longer barrel might have meant a pressure drop at the muzzle, and so lower sound. Maybe once I get the barrel fully shrouded maybe I'll see a difference. I'm just not sure. I think I'll have to remove the barrel to get that extra barrel spacer on too. I can't get it any further on than the original, and I can't get that one on any further than it will go without me contemplating a serious beat-down on it. I hope the additional stiffness will aid accuracy once I clean the barrel. I'm also running into problems with the magazines now that I hadn't before. Cocking is not as thoughtlessly smooth as it was before the barrel swap. Maybe the new barrel is "off" somewhere? An interesting adventure, to say the least.
darryl

Darryl-
I've read that the folks that have swapped barrels in the Mrod have said that when doing so, the set the barrel with a mag in place. This allows for proper depth seating, fitment, and probably alignment too. Also check the inner barrel o-ring isn't jagged up in some way, as that will affect loading and accuracy.

That could be a big issue if you did not do that. That's what I had to do to make sure everything was good.

darryl · « **Reply #41 on:** October 04, 2011, 02:16:17 PM »

hi Guys,
I may try that technique, but here is what I've found with the barrel I got:
*the hole in the barrel that is supposed to align with the transfer port is off center lengthwise to the breech ( a bit forward of center with the screws tightened down)
*the barrel sits off center in the breech so that the bolt does not engage smoothly (rubs against the left side of the barrel as it enters) this causes the next BIG PROBLEM
*the magazines jam constantly because of the barrel being out of alignment with the breech. I've had to tap the magazines out many times, finding that I've sheared the heads off of pellets to get the magazines out.

When I manually load pellets all is fine for the most part. I've had to loosen the the bolts that lock the barrel in place to create just a bit of play to allow the bolt to slide in easily, and the magazines still jam. I wish I had researched this project a bit longer. I might have discovered what you guys are telling me here. It's not simply a drop-in replacement after all. My mistake for taking it at face value.

Dk you're right. It is a big issue.

darryl · « **Reply #42 on:** October 04, 2011, 04:41:09 PM »

Hi RR,
Inner barrel O-ring? I accidentally destroyed that. I did not know it was there when I took a drill, and ...well never mind. That didn't anyway. But about having a magazine in place. when I think about how the barrel is ill fitting as I noted here earlier, I'm not sure I'd be successful in doing that. See, the mags seemed to fit fine. Not hard to insert at all. What I need is a fix for the bolt hitting the left side of the barrel as, I assume, the pellets are too. When everything is tightened up, the barrel is misaligned to the bolt. That is the critical failure, and explains to me why the accuracy is so off. The pellets are being deformed when/if the load. The left side of the pellet head is taking a beating. Now that I've dicked with the barrel there's no sending it back. No room in the breech block to shim the barrel to move it to the left, and so clear the bolt. Meanwhile the P is back to it's original barrel.

darryl · « **Reply #43 on:** October 09, 2011, 12:21:22 AM »

Thanks all for the tips, and encouragement. I've had the elusive success tonight. I got with Gary and Jay today and we went over everything about this barrel, including a good bore cleaning and polishing. I beveled the breech end of the barrel, then gave it a good polish; removed a burr from the inside of the port hole that Jay located (actually he and Gary worked on that burr more than I did- not much left for me to do. Jay had the same suggestion as I got here; put a magazine in place before installing the barrel. I believe the collective advice and efforts of Gary and Jay set the stage for a successful conclusion. I ran 8 magazines through the barrel without a hitch. Good accuracy too, even though I was tired from working on it. That can only improve once I'm fresh. I also tweaked the power a bit and got the P-rod pushing 15.9 grain JSB Jumbos at 634fps (earlier today with the standard P-rod barrel). A new Disco spring should help that out a little.
thank you all,
Darryl

Jay · « **Reply #44 on:** October 09, 2011, 12:58:33 AM »

Was a fun day for sure Darryl, really enjoyed how fast you can change the barrel's out on the Maruader gun's, an being able to see the instant improvement with just a bit of "detail" work on the barrel's, you do a bit more polishing on the longer barrel's breech end with the JB an it should be set to go(glad breaking the sharp edge's helped the feeding Bro.).

RatRacer · « **Reply #45 on:** October 09, 2011, 01:40:39 AM »

Glad you got it sorted Darryl. Enjoy you're next strings after a deflated remedy excursion. It helps to have confident and knowledgable friends to help solve Rubiks cube.

darryl · « **Reply #46 on:** October 09, 2011, 09:41:32 PM »

Jay, it was your (great) idea to bevel the breech end of the barrel. I think that was the trick that made the pellet loading feel so smooth, and very similar to what I was used to with the P-rod barrel. Maybe I'll bevel the P-rod barrel next. Of course a good polishing would be in order too.

BTW, thanks for the o-ring too. Otherwise I'd have had to wait on Crosman to process my order. Now I'll have spares for us.

RR, I'll cosign your statement. I've meet some good people here on the GTA, and have the pleasure of spending good quality shooting time with some of them. Hanging out with SW-Ohio crew is a great way to spend a day shooting and talking airguns.

I think my next test will be to try some of those RWS Superdomes ( a misnomer, imo; not much dome there) as they seemed more prone to jamming than the round-headed JSB Jumbos. If those cycle through OK,I'm in there!

darryl · « **Reply #47 on:** October 10, 2011, 01:20:59 PM »

OK, tried the RWS Superdomes. They load just fine. I've decided to fill only to 2500 PSI for now. That seems to be where the best accuracy begins @ 30 yards. Since I'll be going for a fully shrouded barrel, I asked Jim if he thought the shroud spacer he's making for me would also aid in quieting the gun down a bit more. He replied that it should since the volume of the shroud is increasing. I'd thought the longer barrel sounded louder to me before, but it doesn't seem like it now. Maybe when the spacer arrives I can do a before, and after test, and post it. Feeling pretty good about how things have turned out.
SO, is the Disco spring the way to go for better control of the air release?

DeutschKSK · « **Reply #48 on:** October 10, 2011, 01:34:27 PM »

Glad to see you are having some good things happen! I still need to detune mine down to 12 ft/lbs of energy. But if you are going for more power and higher fill pressures I'd go with the disco spring or an aftermarket spring that is even stronger.

darryl · « **Reply #49 on:** October 10, 2011, 03:10:10 PM »

Hi DK,
I think I want to try for another 100FPS. That should get me 19 FPE with the JSB Jumbo. How to do that is what I need learn. I also may want to do the ice-maker water line trick to free up the transfer port too. Lots to read about. The P-rod is only pushing 14FPE right now with those 15.9 grain Jumbos. I guess I'd be OK not going up to 19FPE. Not like I'm hunting ground hogs or racoons. I'd like to make a spinner spin at 30 yards. That might be a stretch.

rsterne · « **Reply #50 on:** October 10, 2011, 05:23:41 PM »

It's interesting that you guys are having trouble getting up to the 20 FPE range with your PRods.... unless I've missed something along the way.... My 2260 based Grouse gun shoots 16 shots at 19-20 FPE starting from 2000 psi down to 1100 psi and it does that with only a 0.125" transfer port.... Lowest velocity is 674 fps and the highest is 709 with 18 gr. JSB Heavies, for a 5% variation, which is no problem as all my shots are within 40 yards max.... I'm using a Disco hammer spring, BTW....

I'm wondering if the PRod valve is restricted compared to the Disco valve?.... I have a .25 cal MRod valve here, and it has a SMALLER exhaust port than the Disco.... presumably because of the higher fill pressure.... Just something to look at, maybe?....

Bob

RatRacer · « **Reply #51 on:** October 10, 2011, 05:36:58 PM »

I can't find the link that I read, but I believe it said the valve port is .103.

rsterne · « **Reply #52 on:** October 10, 2011, 05:50:35 PM »

The stock Disco valve port is 0.152", transfer port is 0.140" and barrel port is 0.134".... A typical "power tune" will increase the transfer port to 0.162-0.166" and the barrel port to 0.166-0.171".... and the valve port to 0.157-0.162" on a 20 degree angle with streamlined corners....

Bear in mind, this is for a 2000 psi gun, not a 3000 psi gun.... On a 3000 psi gun, ports that large may very well produce a very curved (and therefore short) shot string....

Bob

darryl · « **Reply #53 on:** October 10, 2011, 09:55:47 PM »

I drilled the port out to 0.0937 (3/32)". I'm still using the stock hammer spring (max-adjusted along with the hammer throw being maxed too). From what I've seen online, this configuration should yield me 16FPE with 14.3grain CPDs. I'm using JSB 15.9 grain pellets though. One magazine took the fill from 2700 down to 2150. Need to put it across a chronograph to know what it's really doing. I'll need to be pushing those pellets at 675FPS to get there. So basically I'm flying blind.
Bob, would the Disco spring be of any benefit if I only wanted 16FPE? Maybe provide a means of finer tuning? NO need to go 20FPE. Got a Pneuma to handle the heavy work.

darryl

rsterne · « **Reply #54 on:** October 10, 2011, 11:02:48 PM »

There are too many variables to be able to tell you if a Disco spring is necessary in a PRod.... and we'll never see them in Canada because of the shroud.... Rule of thumb.... if you can get more than 16 FPE with the spring you have.... then a heavier spring is not necessary.... The only exception would be if you want to increase the fill pressure and choke up the transfer port.... then you might need a stiffer spring....

Bob

darryl · « **Reply #55 on:** October 11, 2011, 10:25:58 AM »

thanks Bob,
don't want to go overboard beyond a set goal. If I don't need it,I won't add it, per the goal.

DeutschKSK · « **Reply #56 on:** October 11, 2011, 11:07:39 AM »

I go overboard on all my stuff! Mike of Citrus Airguns is going to be getting my Mrod in the mail pretty soon for a complete make over.. LW barrel, 30" airtube, tune, and more!

darryl · « **Reply #57 on:** October 11, 2011, 01:49:25 PM »

I can't spend too much money on the P-rod. Have to save for the next big thing.

Actually since I don't hunt, I don't need any more power than my Pneuma (Hatsan AT44-10) can deliver (once I get it back from UMAREX. It can't hit a ding-dong at 10 yards with a magazine in it; it's killer accurate when loaded manually, but I didn't buy it as a single-shot rifle).

Mark 611 · « **Reply #58 on:** October 12, 2011, 09:38:40 AM »

With all this stuff you guy's are doing with these P-Rods your makin me want one! but does anybody know if the bolt is switchable to the left side so us southpaws can use it correctly? have you guy's seen this?

darryl · « **Reply #59 on:** October 12, 2011, 09:59:01 AM »

yep, seen it. bookmarked it too. I'd like to see similar results posted on You Tube while using heavier pellets, and the Mrod barrel. If I had a chrony...well. I don't yet.

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Prod upgraded!

Author Topic: Prod upgraded! (Read 30059 times))

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