GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: toddbrat on July 25, 2017, 12:23:36 PM
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Thinking about adding one to my .177 Maximus and looking for thoughts from anyone that has. Has your accuracy changed any? How well does the shroud work? I have a TKO on mine now to make it backyard friendly. It is crazy accurate and should probably leave well enough alone but...
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There ain't nothing like a repeater.... just sayin..
As long as everything seals up like it did before I don't see a problem. Your accuracy is going to come from consistent power from shot to shot and barrel.
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I have one on my discovery. Absolutely love it. The only thing to remember is not to point the Muzzle up when chambering a pellet, It can cause a jam, it's not really an issue with the breech more an issue with the magazines if they don't put enough pressure on the pellet. That can be solved by moving the spring for the mags to a different hole. I had a TKO on it before the shroud and It may be slightly louder but still very backyard friendly. I had no accuracy issues. I did notice a slight increase in power with the TP that comes with the breech. Installation was a breeze.
Phil
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Thanks guys, it is still a couple of months out if I get one, just looking for opinions. That's my biggest want, really, is a repeater.
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How do you convert a Discovery .22 to a multi-shot breech. That would be greatly helpful in my pest control.
Thanks,
ACZan
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How do you convert a Discovery .22 to a multi-shot breech. That would be greatly helpful in my pest control.
Thanks,
ACZan
You can buy the multi shot (repeater) breech here
Bnmcustom.com
You don't have to buy the shroud but I did because I liked the look on other discoverys I saw. Mine is in 22 caliber. Here is the finished rifle. Oh and you just use 22 caliber marauder magazines.
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I put one on my .177 Maximus last weekend and couldn't be happier with it. I had some initial misgivings but once I found my mistakes it really changes things. The one area of concern is the new height. I have a 50mm scope and will need to put a smaller one on, I can't get a good cheek weld and it is causing accuracy issues.
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Very nice setup Lmgunner13!
The original breech is a 11mm scope rail, right? What is on the BNM breech? It is the SKU : BMDSH3002 one, right?
I need to really keep the Discovery level power and pressure 2000 PSI compared to the Marauder. But, have always desired the repeater feature. I am struggling with a second bad bent barrel. Second one is even worse with no visible rifling at the muzzle. So, if I am going to change the barrel again, then I might as well consider getting a better breech.
ACZan
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I just bought a Maximus and since wished I had bought that little Chinese repeater. How much does this new breach cost?
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I just bought a Maximus and since wished I had bought that little Chinese repeater. How much does this new breach cost?
Bingo !!!
But, if you already have the Maxi or Disco......
But then again..... I would probably sell a Maxi or Disco and put the money towards the 3k Varmint... Unless I was hand pumping.
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Someone needs to double tube the Varmint.
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You can get the BNM breech in Dovetail or weaver/picatinny. But I have to agree with Avator you can buy the Varmint for about the same as the BNM breech and shroud. You will also have to do the 3000psi Mod to your disco or maximus. Might as well get one of those SPA guns from Mrodair. Now if you like to like to tinker go for the breech. I had a blast building my disco.
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Oh yeah, don't get me wrong... The experience and fun I had with my "lego" builds was priceless. But if I'm just going for the end result I would go via China.
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Oh yeah, don't get me wrong... The experience and fun I had with my "lego" builds was priceless. But if I'm just going for the end result I would go via China.
I'm about to take the plunge on a mrodair Airmax just not sure which one yet.
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I went the more expensive route but was able to spread it over a few months to lessen the pain. I wanted a Maurauder but couldn't justify the expense at the time. I liked the 2k fill of the Maximus as I could get a used 3k psi scuba tank for free. I'm very happy with my setup but if had it to do over I would have gone with the Varmint or Maurder off the bat.
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Phil..
IMO The Plinkster is just that... a plinker. If you want a to stay in the lower price range hunter go with the Varmint. I chose .177 to share mags with what I already had and I'm glad I did. Perfect accuracy and power for my intended range. I can't speak of the higher price range SPA guns because I have no interest in them.
Todd..
I hear you about the budget. I would not have my SynRod had I not stumbled into a trade for it. I had a continuing craving for a GAMO Urban but I'm resisting. The cost of spare mags helps me refrain.
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Bill, buy the Urban! ;D
I've got one and it takes me 30 seconds to load the mag. $50 is way too much for a magazine IMO, and won't buy another unless it breaks. I only fill mine to about 2500 since my tank is 3k. I get 2 mags then need to top off again but with H&N field targets those 20 shots are one hole at 50 yards.
The trigger is a bit mushy but keeping in mind this isn't designed as a match rifle it is very serviceable.
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Bill, buy the Urban! ;D
I've got one and it takes me 30 seconds to load the mag. $50 is way too much for a magazine IMO, and won't buy another unless it breaks. I only fill mine to about 2500 since my tank is 3k. I get 2 mags then need to top off again but with H&N field targets those 20 shots are one hole at 50 yards.
The trigger is a bit mushy but keeping in mind this isn't designed as a match rifle it is very serviceable.
Phil..
IMO The Plinkster is just that... a plinker. If you want a to stay in the lower price range hunter go with the Varmint. I chose .177 to share mags with what I already had and I'm glad I did. Perfect accuracy and power for my intended range. I can't speak of the higher price range SPA guns because I have no interest in them.
Todd..
I hear you about the budget. I would not have my SynRod had I not stumbled into a trade for it. I had a continuing craving for a GAMO Urban but I'm resisting. The cost of spare mags helps me refrain.
I love my Urban...deadly accurate with JSB's 18.1
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I fill my 3000 psi tank to 3300 psi at the fire station. Burst disc in all 3k tanks is 140% so 110% isn't going to hurt anything. Get way more fills that way. Even though I have the 3k psi mod on my discovery I never fill over 2300 psi, the Prod gets 2700 psi and the hatsan gets 2900. I can usually shoot for a couple weeks on a fill. A compressor is next. Remember that rabbit hole? Yeah I'm in it...
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I'm enjoying the BNM Breech. Phil helped me with my decision. "Thanks Phil"!!!
I too would have bought the SPA, but------they weren't really available, or tested when I picked up the Max. ANd I've not seen a single target from one of the SPA's yet that can match what this .22 Maxi is doing.
I've watched quite a few Urban vid's an there again, just not impressed with what is being shown. They may very well be tack drivers, but no vids show them as such. Odd, as the BSA Bbl's are famous for their accuracy.
Very interested in the MK II spa with the bottle. But they are going to have to show real accuracy for me to plug down the bucks! ;)
Knife
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Phil.... If I'm being honest, my Varmint in .177 shines at 2700 psi. Filling to the full 3k unregged is virtually fruitless. Not worth the added pressure on the weakest parts of the gun... the O-rings. I can't speak to the characteristics of the .22, I don't have one.
I have a deal with Betty Lou.. Any future guns I buy would be funded by selling guns we already have. Bless her heart. I don't own a single gun that would bring me enough to fund the Urban except ones that I don't wish to sell. We now own the Varmint, the .22 SynRod w/tss and mds and a pair of hpa converted "lego" carbines. This makes the Urban more of a want than a need. I've listed a couple guns in the classifieds with the goal in mind to fund the Urban... The problem has been that before I reach the needed funds one of you enablers point out a "must have" deal and I get weak..... lol
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Bill,
You have one of the Mrodair compressors don't you? Is it doing the job? I am thinking before I get another rifle I should get a compressor.
Phil
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Yes, I have the MKII with the auto shut off. I use it to top off my 2 3300 scuba tanks. 1 at 100cf and one at 80cf. I've probably topped of each 10 times no with no issues. I was not around for the first go round with the MRod Air compressor fiasco but I've read about it. This new model reportedly addressed those issues. I obtained mine from MrodAir through a trade deal and like I said... so far, so good.
It fills the 100 cf from aprox. 2500 to 3400 in just under 20 minutes and, once I figured my water cooling out, the max temp is 54c with no stopping to cool during the fill. I do live bleed a couple times during a fill. I choose not to fill gun directly... it fills too fast for me to be confident in the auto shut off. Stuff happens you know. It will top off a 3k gun in less than 15 seconds. Not much room for error.
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So, 11mm Weaver is one of the choices. I might be able to use my current scope and rings. But, it is a low profile and need to check for clearance with the magazine.
Can you put just the barrel on the BNM breech without the shroud? Or, is it only manufactured for the shroud? Would be nice to put a custom thicker barrel. Instead of the soda straw ones.
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It is available for either with, or without shroud. I ordered a breech made for the shroud. ( The breech that arrived, was for no shroud. GRRRR!!! ;D
Knife
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KnifeMaker,
That is good news that I can get one without the shroud. I intend to use my TKO silencer. Obviously the barrel band will need to be change out with the increase distance between the air tube and barrel. Unless, there is no change on that dimension. I am having trouble with getting a good replacement barrel from Crosman. Asked a manager to go through his inventory to find one for me, special request. Anyone have any suggestions to a good barrel to use with this BNM breech?
ACZan
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BNM has a barrel band for the barrel only. I have one on this one.
Knife
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Is that a two set screw or a six set screw band?
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I think it is a single screw in the bottom. Wait that is the band with the shroud, not sure about the one for just the barrel. I ended up doing 5 set screws for the part of the band that goes around the air tube and left the shroud portion without any.
Perhaps I should have not answered as I believe you are looking for the one with just the barrel.
Dave
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Single screw on bottom for tube. BBL. is an "O" Ring. ;)
Knife
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Well, you guys have me convinced to seriously consider a BNM custom upgrade on my rifle.
I considered replacing the Discovery with a European version, but I just couldn't find a foreign one with the fundamental characteristics with which the Discovery was designed and I like.
I did speak to Sergio at BNM a little bit about the repeater breech. I was concerned about the drop in the fps going to the BNM breech. I really need to try and keep it at the factory 900 fps level or close. Does anyone know if and by what the velocity drops with the new breech? I did get a bit of a drop into the upper 700s with the replacement of the barrel. Don't know why that happened. If there is a drop BNM breech, what can be done to compensate for that?
I would really love to replace the plastic trigger housing with a metal one. Would be willing to drop some cash to make that happen. I just don't like having plastic in critical places. My Pontiac 2000 Grand Prix SE with the 3800 Series II engine had way too many plastic parts that were failing on a regular basis.
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My valve-tp-barrel seal was leaking in the factory set-up. I drilled the BNM thru port a bit bigger, and matched it to the barrel/ valve port that I had ported. FPS went up, due to less blow-by.
I replaced the plastic trigger group with the MRod Gen I Trigger Group. Man, what an Improvement!!!
Knife
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KnifeMaker,
What did fps go from and up to after the modification?
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Crosman would do well to add a repeater breech for the "lego" guns in the CCS.
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I would love an off the shelf repeater at 2k. Going to go out on a limb and say I've *finally* gotten my BNM where I want it, well almost, waiting on some Krytox to get here. Looks like I can track down my shotgun patterns to a bad scope; I thought it was holding zero and maybe the shroud/barrel was moving or was getting some clipping. Bought a laser boresight and while using that at 25 yards to align the scope, what should have been a small adjustment of less than 1/2" moved almost 6"! To test the theory, I stopped moving the turrets and gently thumped the housing near the turrets. The dot swung from 2" left of the line to almost 5" right of it. Guess that's what I get for buying cheap scopes. Put an old scope on and it is holding true. And I missed the Amazon return window by 3 days...
Anyway, loving my "new" rifle. Next up is a FFH and power adjuster to try to flatten the curve out, it is steep enough I get more POI shift than I'd like at 50 yards.
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Without changing spring setting, it went from shooting 14.3's at 880 to high 890's, so backed the spring pressure down a bit.
The Crosman domes are odd beast in my AG. Cheap, and shoot well, but not over 880's.
Knife
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I know they cost a bit, but a good scope is well worth the money spent. ;)
Mine are Zeiss and the Athlon 6.24 FFP. Both are completely accurate in their tracking.
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Those are some nice scopes. I'm too cheap to spend the money on them, especially when all I do is poke holes in paper. With that said, I do have my eye on a nice PB that'll let me poke those holes at 1000 yards plus and if I get it that will definitely be dressed for success...lol.
My Maximus is .177 and really shoots the Snipers, both medium and heavy as well as Monsters really well.
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Crosman would do well to add a repeater breech for the "lego" guns in the CCS.
No kidding. Might even save their bacon from the Chinese repeater invasion.
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Crosman would do well to add a repeater breech for the "lego" guns in the CCS.
+1
And the option of a two stage trigger (Prod trigger and hammer assembly).
But so as to digress no further and bring it back to the BNM breech, here's my disco with their breech and shroud.
Blue
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Well, I am going to have to rely on you guys' advice when I get started on the BNM breech project.
BTW I thought that my current erratic POI on my barrel replacement was due to scope. It is a Vism 1.1-4X 24mm Evolution Series Scope which I believe were designed to be used more for AR 15s. So, those should be able to take a bit of a beating. However, it might be best to take the rifle back out to range and throw my Steiner MBS-AA Laser Boresight on it between shots and rule that out as the cause of erratic POIs.
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Bill, you hit the nail on the head! Crosman would be well advised to add a multi shot Disco/Maximus to their line up. They are getting passed in the emerging "Low End" PCP World.
Exciting times we live in! 8)
Knife
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Do any of you guys know how much clearance I need from the groove of the 11mm dovetail on the BMDSH3002 breech and above it to avoid any scope interference? I have low mount scope rings. Does the pellet clip engage and disengage sideways from the breech?
On a side note, my rifle took a hard fall onto concrete yesterday. Thought that was the end of it, at least for the scope. Took it out to range. Thumped it hard between shots in different directions, still held zero. Still believe my erratic POIs have something to do with the barrel not being optimally machined. My NcStar scope has certain lived up to its name, claim and definitely worth the money.
Thanks,
ACZan
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Guess no one knows on this. So, I contacted BNM Custom. The said that the clip extends 0.395" from the 11mm dovetail groove to the top of the clip. Measuring from the groove to the bottom of the scope tube, I have around 5/8 or 0.625. That's just enough to clear my BLK low mount scope rings and my NcStar scope.
KnifeMaker,
I am preparing for a mod on my Discovery .22. I have to have a repeater on rifle and a better barrel (too many bad Crosman barrels). In the next week or two, I will be ordering the BMDSH3002 breech from BNM Custom.
Also, I am working with Roy at Mountain Air Custom to have him turn/machine a new Lothar Walther barrel to fit the BNM breech and accept my TKO VMod suppressor.
The last thing I need to work out is determine what needs to be done to maintain the 920 fps. Did you figure out everything that needed to be done to recover the velocity with the new breech?
Did your BNM breech come with the port sleeve and connecting hardware?
Thanks.
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Chris;
Yes it did come with all hardware. Including the longer transfer port tube machined from alu. Didn't have to do anything but add a hammer spring adjuster.
Playing with a HUMA Reg now. A bit down on power. New spring came in yesterday, but terrible weather here in central Tx.
Biggest reason the power is down, is that I got a wild hair and shortened the barrel by 4.5". I got tired of banging the LDC into everything I got close to in the woods. LOL!!!
Put the larger dia. Rocker1 Carbon Fiber LDC on it as well. Man it's good looking now. 8)
More testing when the weather improves. ;)
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Oops, meant port tube. Hate when I don't call things by their proper name. But, you knew what I meant.
So, There is nothing that will need to be done to the BNM breech, port tube or the barrel to recover the velocity? Anything that needs to be done to those parts, I have to have Roy do at Mountain Air Custom while he has it. Want to make sure things are done right first time around as opposed to the tuner who did work on it previously. I found out after I got the rifle back from him there were problems, when he should have told me while it was disassembled.
At what velocity did it start shooting after the new BNM breech was installed? Based on the graph report the tuner sent back with my rifle still with the factory configuration, it was down in the lower 800s. I am fairly sure now that the tuner did some bad work on the gun. So, the mid to higher 800s will be a good start if anything at all.
Do you think you can get it back to the 920 fps factory spec? Oh, wait a minute, you have the Maximus. Those are rated at a lower velocity, right? Do you think those Discovery .22 rifles actually shoot at that velocity shortly out of the box following their break-in period?
Yep, know that all too well. Think my TKO VMod is 6.5" long. I have knocked it a little on several occasions thinking that I moved the barrel out of alignment again. With the BNM breech, I can have new barrel band style I came up with made for the new configuration. Should stiffen and align the air tube and barrel assembly quite a bit. Haven't decided what diameter L/W barrel I want to get, thinking little thicker than factory stock. Do you have any suggestions?
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Yes, I see all that really bad weather down there on my desktop radar map widgets. My older Brother told me some stories about the weather in Lubbock, TX.
I know about the hammer spring adjuster. I can just put in a different spring with out having the adjuster screw, right? Looks like there are a variety of springs which can be installed.
What is the MUMA Reg? Not completely familiar with the abbreviations on the part names.
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::) LOL!!! Misstyped.It is the HUMA brand Reg. LOL!!!
Lost 60 fps when shortening bbl. Before it was 890's with JSB 18's, and was the same with the BNM.
New spring arrived and will install probably today. I really enjoy the hammer spring adjuster. Just dial it in in a second or two. Ordered it from Joseph here on the GTA. His business in Discos-R-US 8)
Knife
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Okay, found it, now. It is a Huma-Air Pressure Regulator (pictured below). I was not familiar with that component and it appears to be one that is inside the air tube. Looks to be very well made. May have to consider upgrading the air tube components in the next reseal maintenance. Seems like there are a lot of nice high quality after market parts for this rifle.
I can live with it shooting in the 890s range. Did find out that the L/W Barrels are only available at 23.75" in length. Being one quarter inch short shouldn't be a problem. The BNM breech is a bit higher which will allow a little more of the barrel and its components to clear the air tube.
Would really love to replace the plastic trigger housing with a metal one of the same shape parts. Have a lead on something I found on the Internet. May have to pay a pretty penny for that and will if I have to.
Did the machined arch on the bottom of the BNM breech match up well with the curvature of the air tube? That would be key to the air tube, breech and barrel aligning very nicely with each other.
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Breach fits perfectly. ;)
For an outstanding trigger, most go to the Gen 1 Marauder trigger with the spacer.
Again, Discos-R-Us has them, and at the best price I have found.
The MRod trigger is a clone of the world renowned Rapid airgun triggers, and what is very similar to the trigger group found on the very nice, high end RAW AirGuns.
Knife
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Does anyone know what the overall length of the BMDSH3002 Breech is without the shroud?
Correct me if I am wrong, but I believe it has to be roughly the same as the Crosman stock breech. I was worried that the BNM breech might have differences in the X dimensions that might cause the barrel to be shifted. However, the BNM breech needs to match up with the port and mounting screws which means it is nearly the same in size if not exactly the same.
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Never mind looking that up, guys.
BNM Custom got back with me this weekend and confirmed the breech is the exact same length as the Crosman stock breech, 6 inches.
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KnifeMaker,
Finally received the BNM BMDSH3002 breech. Strangely, they sent me the wrong one, for barrel shroud, instead the non-shroud one. Did specifically mention the non-shroud model number, but still sent the wrong one. On a good note, they got the right one out to me in a short time.
That aluminum transfer port tube has two different ends. Do you know how it is orientated? I assume the one o-ring seal fits on one of the ends of the tube.
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LOL, I ordered for shroud,l and got non shroud breah. GRRRRR!!!
Not sure on the tp tube. I ended up using the old standby ice maker tubing. almost seems to be a standard among tuners and owners who are searching for power. Crush to seal.
Knife
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Looks like we had the opposite problem. I was wondering about going to a press to seal, much like some HVAC and plumbing connections.
I had a airgun tuner give me a big list of reasons why Crosman and BNM repeater breeches diminish shot accuracy compared to the stock setup. I sent you a private message with the full text of it. I'm really interested to hear your comments on it. The tuner was making it sound like I made a very bad decision.
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KnifeMaker,
I received the L-W custom barrel from Mountain Air Custom. The barrel looks great except for one thing, the port on the barrel. Looking at the photo with the Crosman factory barrel next to it for comparison with the transfer port tube next to it.
On the custom barrel, there isn't a prominent seat on which the tube sits. It looks a little tapered but not much. Is this how yours looks? The way it was machined doesn't look like the BNM Custom transfer port tube which came with the breech will work with the way the barrel port was machined.
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A closer look at the port shows the taper machined into the barrel appears to be off center from the hole. Also, it almost looks as if the port was opened up too much.
How do I deal with this, or do I need to have another barrel made?
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Okay, had to take apart a spare BNM breech to see how the transfer port assembly is set up. It is obvious the TP tube stops at the bottom of the counter bore beyond the o-ring in the block. Is there a name to refer to this block attached to the main body of the breech?
The first photo is the block turned over to the left side to expose the TP to the barrel. The second photo is the block rotated 90 degrees to show the bore and o-ring for the barrel.
So, there three o-rings. One for the bolt, one for the barrel and one for the TP tube.
Anyone know what end of the TP tube goes where? Don't recall those instructions being packed with the breech.
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Anyone know what end of the TP tube goes where? Don't recall those instructions being packed with the breech.
I don't remember either but I do remember watching their assembly videos online a couple times when I originally got mine. If their videos are still available there might be something in them that helps.
Blue
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Okay, found the info on which way the TP Tube is supposed to be oriented. I attached a photo with text.
Also, I took some time to measure out the elements of the BNM transfer port assembly. Don't have my CAD software installed yet. But, this is the best I can do with Microsoft Word. Placements and dimensions will be a little off. However, it is a good representation of the assembly. Obviously the yellow object is the BNM TP Tube. See some slight issues which could lead to air leaking.
Can anyone tell me what the largest size hole can be machined into a .22 cal barrel for the transfer port? I can see too large of a hole causing problems with loading the pellet into the leade.
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KnifeMaker,
Here is a close up of that o-ring inside the opening of the breech to the leade.