GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: mackeral5 on April 12, 2021, 08:51:11 PM
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As always, I was late to the Crosman/Benjamin party, but I'm finally here... I picked up Dillon's 1720T Rapid-70 Bullpup, it arrived today along with a 1/2-20 adapter. I pulled an older Tanto out of inventory and was pleasantly surprised that fitting a Tanto with cone style end allows for fills without requiring LDC removal. I found a set of medium rings and an old Bugbuster scope to start out with--this will likely be short-lived as the Bugbuster's very fine reticle isn't a good fit for my contacts prescription.
Anyway, here is a quick pic after shooting a bit and growing aggravated with a loose pistol grip which required close to full disassembly. I added back up washers and loctite to the 2 grip boss/adapter screws. As a sidenote, I don't see why a determined individual could not make a grip adapter to accept AR grips... The Rapid-70 grip appears to be something adapted from perhaps a CO2 pistol of sorts? it has an out of place mechanism in the trap door and is strangely, overly complex for a grip.
(https://i.imgur.com/QPIdzJ3.jpg)
A few quick shots over the chrony with Crosman heavy domes showed velocities in the 690fps range.
More to come. It is going to have to have a magazine, eventually.
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Very nice!! I like it!
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Congratulations! That is one sweet looking pup! You and Dillon have great taste in PCP’s 😉. Enjoy shooting it.
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I don't like that design... but that's me...
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Congrats on the new pup Mike. I'll be interested in how you source a mag for it.
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Thanks for the responses.
I don't like that design... but that's me...
It is definitely ugly....and fairly complex, yet simple in many ways. For example, once I am ready to tackle a tuning process I will likely convert back to the OEM configuration. For now I am really enjoying shooting a gun that sips air and can stack pellets at 40 yards. This design does not lend itself to quick/simple disassembly/reassembly. But, such is the case most of the time when guns, etc are altered so drastically different from their original form.
With that said...Rapid-70 did an awesome job of designing this kit. The trigger system works perfectly and does not modify the factory parts in any way.
Guns do not get much lighter and more compact than this.
Plans include a magazine breech, a regulator and I will likely modify a valve to include a peek poppet and Cobra Chamber. Will likely become a dual caliber gun as well.
But again for now I am really enjoying it as-is.
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I kinda like it!
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In my experience after I put my cheek to the rest all I see is a cross hair. So I don't care a whole lot about looks. I had his OG bullpup and loved it, best backpack gun. If you gas it to 25+FPE it becomes a very capable little gun. Mike it looks great you'll love it!
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Welcome to the "small" tube crosman lego gun world! :)
Those Rapid-70 BP's are tiny!
Even if it didn't need a LDC, I would, just to prevent shooting my left hand. :o
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Welcome to the "small" tube crosman lego gun world! :)
Those Rapid-70 BP's are tiny!
Even if it didn't need a LDC, I would, just to prevent shooting my left hand. :o
As pictured 5lb 5oz, with those heavy UTG quick detach rings I'm sure a more appropriate set of rings could shave a couple of ounces. 25" long with the Tanto, 20.5" without.
Yes, risk of shooting one's hand/finger is real with this one. The 1720 is fairly quiet, but adding the Tanto makes it even more so. I definitely feel more safe with the Tanto vs without.
i hope this is my only foray into the small tube crosman world---I have more than my share of 7/8 tube stuff albeit in QB form vs. Crosman. I have already come up with a few different Lego configurations to put together, some for only a brief period just to test/demonstrate platform flexibility.
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The Rapid BP stock makes for a great truck & carry gun for sure. The looks are not for everyone, but I sure like it, super small & lightweight. I agree with finger protectors on this BP with factory shroud. Rocker1 sells some factory shroud diameter LDC that is about 3ish long which would be good for lower-powered BP's.
Nice looking shooter Mike.
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The Rapid BP stock makes for a great truck & carry gun for sure. The looks are not for everyone, but I sure like it, super small & lightweight. I agree with finger protectors on this BP with factory shroud. Rocker1 sells some factory shroud diameter LDC that is about 3ish long which would be good for lower-powered BP's.
Nice looking shooter Mike.
exactly my thoughts
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The Rapid BP stock makes for a great truck & carry gun for sure. The looks are not for everyone, but I sure like it, super small & lightweight. I agree with finger protectors on this BP with factory shroud. Rocker1 sells some factory shroud diameter LDC that is about 3ish long which would be good for lower-powered BP's.
Nice looking shooter Mike.
Thanks Randy. I have enjoyed it so far. I like the looks/length with the Tanto. I am considering a shroud-length barrel to make it a little easier to get pellets up to speed. Probably sleeved in cf and breech counter bored so the sleeve is inserted. Then setscrews between the barrel band and barrel. Everything i've experienced with bullpups tells me to make the barrel/pic rail a solid connection to prevent wandering POI due to barrel bumps, etc. The free floating barrel seems a bit unstable, though the barrel band is in place and prevents significant movement.
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I have read that you can grind the bottom of a Mrod 177 mag to fit.
My prod takes Mrod 10 shot 22 mags, I do have a new prod magazine in the card package I ordered by mistake but those holes are too big to help you Mike.
Regards,
Roachcreek
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Mike,
On my Mrod barrels for the Prod I use a barrel to barrel band adapter that takes up the room so the barrel is non floating and it works very well in .22 & .25 cal Prods. One is secured with an oring that fits tight and the other for the .25 barrel is held in by 3 set screws in the barrel band. LDC are slip on units from a good friend of mine. My stock or shorter length barrels haven’t had any issues but I’m cautious about bumping the barrels on it. They get beat up in the Jeep on back country and fire access roads and I have never had a zero issues. I almost always check zero anyways before hunting but after I don’t worry about again until the next outing
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Mike,
On my Mrod barrels for the Prod I use a barrel to barrel band adapter that takes up the room so the barrel is non floating and it works very well in .22 & .25 cal Prods. One is secured with an oring that fits tight and the other for the .25 barrel is held in by 3 set screws in the barrel band. LDC are slip on units from a good friend of mine. My stock or shorter length barrels haven’t had any issues but I’m cautious about bumping the barrels on it. They get beat up in the Jeep on back country and fire access roads and I have never had a zero issues. I almost always check zero anyways before hunting but after I don’t worry about again until the next outing
Randy- thanks for sharing this experience. I recall following your Prod builds over the years. I have noticed a slight wandering POI between shooting sessions. It groups tight, but at 40 yards POi moves around a little bit--like in a 1.5" circle. Groups hold to .5-1" but the groups' relationships to the POA move around When removing the dust cap to fill I believe I am slightly tweaking the barrel as it is all but impossible to do without putting some degree of pressure on the barrel/shroud assembly.
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I think occasionally of repurposing my LW poly choked barrel from my dead Skyhawk. I would get serious about it if I did not shoot only low power and it has a MM on it now.
Roachcreek
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Huma ships FAST....ordered over the weekend, it arrived today. I will be using a longer plenum (IIRC this is for a Disco.) The valve has been modified with a .240" OD peek poppet with a 2mm stem and a Cobra chamber. While not needed for .177, I went ahead and reduced stem diameter for a couple of reasons--1) I already had a peek poppet left over from previous P15 tuning and 2) I plan to have a .22 caliber change kit to go along with the .177. Going to a 2mm stem made throat area equal to approximately .160 porting, which is more than sufficient for whatever I would want out of .22.
The .240" OD peek poppet seals on the inside taper of the OEM valve seat. This should result in very minimal hammer strike being required. Which is good, as my ultralight peek hammer only weighs 9 grams, lol...
(https://i.imgur.com/5T6u2y9.jpg)
Hopefully it all works out. The biggest concern is hammer strike. I can make up some brass hammer weights if needed. Hopefully I won't have to though...
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Hammer strike did not end up being a concern. Being I had no idea where this extreme set of changes would end up, I made the hammer to accept a larger than stock spring in both length and OD. When I first put it together it was wasting air and shooting in the 760's. I had to clip coils and put the hammer in free flight to stop wasting air.... Right now it is stable at 750-755fps with Crosman 10.5. Reg is set just under 90bar. Cocking effort is similar to stock. The shot cycle is quick and crisp. A nice "POP" out of the muzzle with the shroud removed. No hammer noise, no ping.
I plan to put a few hundred shots through it in OEM form to ensure everything is stable prior to putting it back in the bullpup stock.
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So far so good. I am planning a tear down for tomorrow afternoon to make the final set of tweaks prior to putting it back in the Rapid-70 bullpup kit.
In pistol form the 1720 is HUGE.
(https://i.imgur.com/igixQwp.jpg)
After a tin of pellets I have to say this is the most accurate .177 I've ever owned. I am not a good shot with a pistol and wasn't taking the greatest care in shooting these groups, but the 1720 consistently does its job. Wherever the crosshairs are aimed, that's where it puts a .177 pellet This target was shot with groups of 10 or 20, and the bottom left bull was a group of 30 shots. The center bull was the first group of 10, then a series of scope adjustments and groups. Distance of 30 yards.
(https://i.imgur.com/SZSzPQA.jpg)
Current state of tune is approximately 45 shots of Crosman 10.5gr @725fps. Tomorrow I will do a final (hopefully) disassembly and this set of tweaks:
Reduce stem protrusion to .200
Increase regulator set point by 3-5 bar.
Through drill/tap the end cap 3/8-24
Clean up the Cobra chamber carrier a bit to ensure adequate airflow to the valve seat.
Possible slight increase of the Cobra jet
I know I am late to the party here, but if anyone wants an accurate, quiet, compact .177 backyard plinker, look no further than the 1720T!!!!
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A quick update. A lot of back and forth Prod/1720/Fortitude hybrid testing has occurred in the past month or so. I have settled on a regulated 1720 tune, somewhere in the neighborhood of 45 shots around 740-750fps of Crosman 10.5gr. I haven't settled on which final versions but I am leaning towards the Rapid-70 kit being a .177 vs. .22.
After a bit of waffling back and forth about a magazine fed 1720, I decided to give it a go. This was after testing my drill press/cross slide vise's ability to run an end mill. I used an old QB78 repeater breech to test with, these were sold by Archer several years back and used Marauder magazines with oring on probe breech sealing. I opened up the magazine well to fit a .25 magazine for a possible future project. This won't be new ground as I have already built magazine fed QB78 repeaters in both .25 and .30. Anyway, QB's are not the subject here.
While we are at it here is a pic of the QB breech in the process of being opened up to fit a .25/.30 marauder magazine. This at least shows what cruelty was in store for the 1720.
(https://i.imgur.com/MDCg0Eh.jpg)
While not perfect and it was a very nerve wracking exercise, I became confident enough to put the 1720 breech in my cross slide vise and have a go at it with an end mill.... Here is the end result.
(https://i.imgur.com/wTIVGMd.jpg)
(https://i.imgur.com/D6YXn7B.jpg)
Magazines are Mrod, with the bottom sanded down a bit to fit. I also run a modified Mrod single shot tray. There just isn't enough meat in a Prod/1720 breech to cut the mag slot deep enough to accept unmolested Mrod magazines/trays, IMO. The probe had to be turned down just a bit to clear the magazines, that is the final bit of modification required.
I still need to finish some file work to clean up the chatter marks....
I now have the 1720 upper mounted on my QB stocked Prod action for fine tuning prior to putting it all back in the Rapid-70 bullpup kit. For now the magazine seems to stay in place with no problems even with the gap. If that becomes a problem I can make a spacer....
(https://i.imgur.com/5MTJQ1f.jpg)
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That's some nice work! I'd say you did pretty darn well with it ;)
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That's some nice work! I'd say you did pretty darn well with it ;)
Thanks Donny. Not perfect by any means, but it is good enough for me and it functions as it should. No loss of accuracy in shooting from the mag vs. single shot tray, which for me isn't the case with every gun....
I finally put the 1720M back together. The more I shoot the Rapid -70 Bullpup kit the more the novelty seems to fade. I may work on an extended/dropped buttplate to see if that helps with the ergonomics. Also need to look at possibly sliding the grip back a bit as the trigger is super close to the grip, worse than my Taurus G2C's....
(https://i.imgur.com/Za99WVZ.jpg)
If someone had a Mrod Gen 1 .25 breech, barrel, and trigger they were willing to put up for trade I may consider parting ways with the Rapid-70 kit itself.....not interested in putting up for sale though.
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While digging through my junk bin I found a couple of old Mossberg 500 stocks that will never get used. So I borrowed the recoil pad off of one of them. This made all of the difference in the world . It shoulders much better and the soft, slightly tacky recoil pad grabs your shoulder very well with little effort required.
(https://i.imgur.com/rJGKC9O.jpg)
I also added a short piece of pic rail just forward of the trigger. Here is another pic with a bipod attached.
(https://i.imgur.com/0U8nxiL.jpg)
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While digging through my junk bin I found a couple of old Mossberg 500 stocks that will never get used. So I borrowed the recoil pad off of one of them. This made all of the difference in the world . It shoulders much better and the soft, slightly tacky recoil pad grabs your shoulder very well with little effort required.
(https://i.imgur.com/rJGKC9O.jpg)
I also added a short piece of pic rail just forward of the trigger. Here is another pic with a bipod attached.
(https://i.imgur.com/0U8nxiL.jpg)
Great Job Mike! That is awesome!
Can you explain how you added the pic rail?
Thanks,
Philip
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Sweet looking BP Mike.
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Thanks... It is growing on me now that I added the butt pad. In OEM form the butt plate is just too minimalistic for my uses. Adding the pic rail to allow for accessories helped as well.
The pic rail is just bolted in place with a couple 10/32 SHCS. The rail was actually a shorted Marlin lever action scope base. Note the space between the sideplates is actually too narrow for a pic rail to fit between. This required a slight narrowing of that section of rail, I made short work of it with a file.
(https://i.imgur.com/9u5eqbn.jpg)
The Rapid-70 kit is neat, and a very practical design. However it has one major design flaw. The core chassis part that houses the trigger sear is made of fairly soft aluminum, IMO it should have been made of steel. I am the second owner of this one and one of the tiny threaded holes that is used to retain a spacer/shim during assembly, this spacer/shim contains the trigger linkage/sear pins, one of the screws was already stripped. Very small, M3 screws threaded into 2mm thick aluminum makes for very fragile threads. Extreme care must be taken when assembling and one must rely on blue Loctite to keep all fasteners in place.
The above described material choice and the pistol grip are my major complaints. The pistol grip should have been designed to accept AR grips. It is very similar, but much too wide for an AR grip. It is almost as if the grip adapter was designed around an existing grip from a CO2 gun. There is an odd, out of place mechanism in the grip that looks like a CO2 cartridge securing system.
(https://i.imgur.com/tqPY5wE.jpg)
(https://i.imgur.com/wPOwIfm.jpg)
Some have reported to use this hollow pistol grip to store items such as a spare magazine. I find it too awkward to open, whatever you store here shouldn't be something that you will need quick, easy access to....
Now I just need to find a way to securely carry 3-4 magazines and this one will be complete.
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Another quick note on .177 Mrod and Gauntlet mags.
I learned that the 12 shot magazines from the Umarex Synergis can be used in anything that accepts .177 Mrod mags.
Currently they are rather inexpensive at 2 for $15 on Amazon.
https://www.amazon.com/gp/product/B07QQGY4VT/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1 (https://www.amazon.com/gp/product/B07QQGY4VT/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1)
These do not block open the bolt on the last shot and have a slight difference in fitment, but they seem to work just fine.
Note the use of Mrod mags in a Prod and this 1720T conversion requires slight clearancing of the magazine's bottom side. This is due to the relatively tight barrel to tube relationship---there isn't enough meat in the Prod nor the 1720T breech to fit unmolested Mrod magazines....
(https://i.imgur.com/FjCLSw7.jpg)
(https://i.imgur.com/rC21D0P.jpg)
This is how they sit in the breech of my 1720T magazine conversion.
(https://i.imgur.com/oLn4IGP.jpg)
(https://i.imgur.com/XiMu12r.jpg)
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After mulling over various options to make the Rapid-70 more friendly towards swapping grips, I remembered some info from my AK/Saiga conversion days.... Most any gun with a flat, sheet metal style receiver/stock can be easily adapted to use AK grips. And there are adapters that allow AR grips on AK platforms. So, all that was required was to cut a square hole in the Rapid-70 kit to allow for the AK style grip nut and we were in business. The AK grip nut had to be narrowed slightly to fit in the piece of channel that makes up that portion of the stock.
Now most any AK or AR grip can be used on the Rapid-70 1720M
I had a Hogue grip in my junk box, so that is what she is wearing for now. With this setup I was able to lengthen the distance between trigger and backstrap of the grip, which is a big help for my medium/large hands.
(https://i.imgur.com/OgaE9n9.jpg)
I used an inexpensive composite AR grip adapter and a steel AK grip nut. Total cost including shipping was less than $20 from Carolina Shooters. Then just add you preferred grip.
This is the AK/AR grip adapter I used. One can choose to purchase higher grades of this unit that are CNC machined/anodized, etc. I went cheap on this one....
(https://i.imgur.com/RcuU3Us.png)
There are also AK grip nuts that are flange mounted and can be screwed to the stock, not requiring the square nut cutout.
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Looks awesome Mike.
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Looks awesome Mike.
Thanks Chris.
The lengthened trigger reach, the butt pad, accessory rail, and 12 shot magazines have resolved most of the things I didn't like about this one. I think it has graduated to "keeper" status.
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After mulling over various options to make the Rapid-70 more friendly towards swapping grips, I remembered some info from my AK/Saiga conversion days.... Most any gun with a flat, sheet metal style receiver/stock can be easily adapted to use AK grips. And there are adapters that allow AR grips on AK platforms. So, all that was required was to cut a square hole in the Rapid-70 kit to allow for the AK style grip nut and we were in business. The AK grip nut had to be narrowed slightly to fit in the piece of channel that makes up that portion of the stock.
Now most any AK or AR grip can be used on the Rapid-70 1720M
I had a Hogue grip in my junk box, so that is what she is wearing for now. With this setup I was able to lengthen the distance between trigger and backstrap of the grip, which is a big help for my medium/large hands.
(https://i.imgur.com/OgaE9n9.jpg)
I used an inexpensive composite AR grip adapter and a steel AK grip nut. Total cost including shipping was less than $20 from Carolina Shooters. Then just add you preferred grip.
This is the AK/AR grip adapter I used. One can choose to purchase higher grades of this unit that are CNC machined/anodized, etc. I went cheap on this one....
(https://i.imgur.com/RcuU3Us.png)
There are also AK grip nuts that are flange mounted and can be screwed to the stock, not requiring the square nut cutout.
Excellent work. Our most sincere congratulations.
(https://i.postimg.cc/ryZLhG7B/LOGO-RAPID.jpg) (https://postimages.org/)
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Although in principle, the design of the bullpup kit did not include a lower bipod rail for "visual aesthetics".
And like many clients, seeing that you incorporated a lower rail, they have asked us if we could include it.
We have decided to incorporate said rail to be able to place a bipod or a flashlight.
Wishing you like it, a cordial greeting.
(https://i.postimg.cc/65GHL99s/IMG-20210602-134305.jpg) (https://postimg.cc/fJDjMQt5)
(https://i.postimg.cc/zBKCHfCp/IMG-20210602-141146.jpg) (https://postimg.cc/qhBh94ZC)
(https://i.postimg.cc/rmrJGjk1/IMG-20210602-141001.jpg) (https://postimg.cc/8JTMNhsc)
(https://i.postimg.cc/K88Dpxbv/IMG-20210602-141203.jpg) (https://postimg.cc/nCNmC8M6)
(https://i.postimg.cc/C1S1JLyc/IMG-20210602-141230.jpg) (https://postimg.cc/7CtwZ4Zz)