just got back from the range after converting a g3 .22cal kit from dan's sporting goods to work in my rdts 51. i had to shorten the carrier, shorten the barrel, use a full size recoil spring assembly rather than my shortened one (just happened to have one ), had to change out my mp5kpdw hammer spring to a g3 spring to get it to run. the 9mm spring works great against .308 but only got lite hits in the .22 conversion so out it came. it took about 200 rounds to get it broke in with a good lube job. by the end of the session it was running full mags with no hiccups of most .22 full power ammo. used cci minimags, blaser, remington gold, vipers, hyperveloc aguila, etc. ; about 10 different kinds with no problems. bursts no problem or let it eat, it did it all. recommend one for every 51 shooter. also the 51 from rdts with ace folder and pdw front grip has been flawless since new. no breakin at all. it functioned perfectly on f/a with everything from blanks with adapter to everything else. also would recommend rdts suppressors for .308 . inexpensive but very effective an are f/a rated. it just takes forever to get a product from him . gun and suppressor over 2 years !! get the .22 conversion and shoot alot more lead
g3 .22cal conversion for hk51
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Thanks for the detailed report!
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Please post pictures if at all possible; interested in seeing the modifications made to the carrier and barrel.
TIA
TIA
g3 .22 hk51 conversion
don't have any pics yet but here is a detailed written which should give you the picture in written form ; 1) there are 2 basic ways to determine how much your carrier tube needs to be cut down to work in the 51 ; 1st you may place the 2 carriers side by side , your 51 carrier and the .22 g3 carrier. line up the front of both carriers where the carrier tubes attach to the carrier. you should see a weld here on both. 2nd now look at the carrier tubes extending from this position. on mine the unmodified .22 unit was about 2 inches longer than my 51 unit. this is how much need to be cut off. you will notice on both carrier tube ends that there is a steel end that is a greater diameter than the rest of the tube . this is about 5/8 of an inch long. you do not have to cut this off and reweld it to the .22 carrier. it serves no real purpose in the .22 unit. just make sure that the .22 carrier tube is cut to the same length as the 51 unit. if it is cut too long tha .22 bolt will not close flush on the chamber. if it is cut slightly too short it will not hurt a thing as this piece is only used to cock the gun and does not move as the gun is firing. you can cut the carrier on a lathe, with a cutting wheel, or a hack saw. the hack saw works as well as anything just make your cut strait.
the 2nd way to measure is to place the barrel/chamber unit in the gun . the 2 slots go horizontal and the small dot in the chamber face goes down. it is held in place by a spring clip and just snaps in. you should notice that you have 6-10 inches of barrel sticking out the end depending on how short your barrel is. you now detrermine how long to cut your barrel. some want it flush with the 308 barrel, i marked mine at the end of the flash hider and cut it a 1/4 inch shorter than that . your choice. the barrel assembly pops back out with only slight pressure on the end of the barrel . agin you can cut your barrel in the same way as the carrier. i do not recommend the cutting wheel or tubing cutter for the barrel. a lathe is preferred but again you can cut it with a fine hack saw with very slow cuts. check for burrs after the cut. you can recrown your barrel by screwing a round head brass screw into a piece of wood and holding the wood put some valve grinding compound on the head and gently rub the head of the brass screw around the muzzle and it will do the job. a ball bearing will do the same or you can take it to a gunsmith and have him cut and or crown the barrel. unless you are wanting match accuracy a gunsmith is not needed on the .22 barrel.
now slip the cut to length barrel back in the the gun and make sure it is positioned and fastened into place . slide you uncut .22 carrier into the gun. you will notice that it is 1 to 2 inches from the chamber face. measure the distance from the bolt face to the chamber face. this is the amount that needs to be cut off the carrier tube end. you can measure both ways and the should be the same. cut the carrier as in number one.
if your 51 spring is the same length as a g3 spring no other spring is needed. if is not then you will need a stock g3 spring assembly to function. i had one in an old green fixed stock so i just slipped the fixed stock on.
warning ; the firing pin assembly is under enoug pressure to launch parts across the room. you really don't need to disamble the firing pin asembly which is done by simpliy pulling out the wire u-clip at the back top of the bolt.
while holding the outside of the boltand carrier in your hand , push the bolt face rearward. you should see the bolt slide backward around that spring that is protruding out the rear of the bolt. you can now put some lube on these moving parts. put the modified unit back into the gun ; it shold fit flush against the chamber. if not see if the 2 slots are lining up with the 2 extractors sticking out of the front face of the bolt . if there is a misalignment , readjust the barrel unit slightly. this is designed so that this should not be a problem. if the extractors ar fitting into the slots but there is a gap between the bolt face and the chamberface you either have not cut enough off of the carrier, you have not pushed the barrel assembly in far enough, there is an obstruction in your cocking handle tube or something like this.
if you were like me you need to have a 308 or 223 hammer spring in you gun. don't expect it to function at all without this. i have an sef f/a pack. put all together and was ready for the range . i recommend cci minimags solids until teh gun begins to get broken in. yes, i know it is a used unit but it still took 200-250 rounds to get functioning in my gun. load 5-10 rounds into one of the mags and make sure the mag locks into place . pull the cocking handle back ; it will not lock into position ;let go forward; a cartridge should feed into the chamber.
get it running on semi 1st , then f/a. mine didn't want to function well even with the cci at 1st. although mine eats alot of different brands of ammo it still doesn't like federal value pack asit kicks it hard enough to ejest a round but not pick a new one up. this should help--dave
don't have any pics yet but here is a detailed written which should give you the picture in written form ; 1) there are 2 basic ways to determine how much your carrier tube needs to be cut down to work in the 51 ; 1st you may place the 2 carriers side by side , your 51 carrier and the .22 g3 carrier. line up the front of both carriers where the carrier tubes attach to the carrier. you should see a weld here on both. 2nd now look at the carrier tubes extending from this position. on mine the unmodified .22 unit was about 2 inches longer than my 51 unit. this is how much need to be cut off. you will notice on both carrier tube ends that there is a steel end that is a greater diameter than the rest of the tube . this is about 5/8 of an inch long. you do not have to cut this off and reweld it to the .22 carrier. it serves no real purpose in the .22 unit. just make sure that the .22 carrier tube is cut to the same length as the 51 unit. if it is cut too long tha .22 bolt will not close flush on the chamber. if it is cut slightly too short it will not hurt a thing as this piece is only used to cock the gun and does not move as the gun is firing. you can cut the carrier on a lathe, with a cutting wheel, or a hack saw. the hack saw works as well as anything just make your cut strait.
the 2nd way to measure is to place the barrel/chamber unit in the gun . the 2 slots go horizontal and the small dot in the chamber face goes down. it is held in place by a spring clip and just snaps in. you should notice that you have 6-10 inches of barrel sticking out the end depending on how short your barrel is. you now detrermine how long to cut your barrel. some want it flush with the 308 barrel, i marked mine at the end of the flash hider and cut it a 1/4 inch shorter than that . your choice. the barrel assembly pops back out with only slight pressure on the end of the barrel . agin you can cut your barrel in the same way as the carrier. i do not recommend the cutting wheel or tubing cutter for the barrel. a lathe is preferred but again you can cut it with a fine hack saw with very slow cuts. check for burrs after the cut. you can recrown your barrel by screwing a round head brass screw into a piece of wood and holding the wood put some valve grinding compound on the head and gently rub the head of the brass screw around the muzzle and it will do the job. a ball bearing will do the same or you can take it to a gunsmith and have him cut and or crown the barrel. unless you are wanting match accuracy a gunsmith is not needed on the .22 barrel.
now slip the cut to length barrel back in the the gun and make sure it is positioned and fastened into place . slide you uncut .22 carrier into the gun. you will notice that it is 1 to 2 inches from the chamber face. measure the distance from the bolt face to the chamber face. this is the amount that needs to be cut off the carrier tube end. you can measure both ways and the should be the same. cut the carrier as in number one.
if your 51 spring is the same length as a g3 spring no other spring is needed. if is not then you will need a stock g3 spring assembly to function. i had one in an old green fixed stock so i just slipped the fixed stock on.
warning ; the firing pin assembly is under enoug pressure to launch parts across the room. you really don't need to disamble the firing pin asembly which is done by simpliy pulling out the wire u-clip at the back top of the bolt.
while holding the outside of the boltand carrier in your hand , push the bolt face rearward. you should see the bolt slide backward around that spring that is protruding out the rear of the bolt. you can now put some lube on these moving parts. put the modified unit back into the gun ; it shold fit flush against the chamber. if not see if the 2 slots are lining up with the 2 extractors sticking out of the front face of the bolt . if there is a misalignment , readjust the barrel unit slightly. this is designed so that this should not be a problem. if the extractors ar fitting into the slots but there is a gap between the bolt face and the chamberface you either have not cut enough off of the carrier, you have not pushed the barrel assembly in far enough, there is an obstruction in your cocking handle tube or something like this.
if you were like me you need to have a 308 or 223 hammer spring in you gun. don't expect it to function at all without this. i have an sef f/a pack. put all together and was ready for the range . i recommend cci minimags solids until teh gun begins to get broken in. yes, i know it is a used unit but it still took 200-250 rounds to get functioning in my gun. load 5-10 rounds into one of the mags and make sure the mag locks into place . pull the cocking handle back ; it will not lock into position ;let go forward; a cartridge should feed into the chamber.
get it running on semi 1st , then f/a. mine didn't want to function well even with the cci at 1st. although mine eats alot of different brands of ammo it still doesn't like federal value pack asit kicks it hard enough to ejest a round but not pick a new one up. this should help--dave
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431 Posts
Thank you!
5000 hk51 .22 report
just got back from the range again after putting another 1000 rounds thru my hk51 .22 conversion. i now have put 5000 rounds thru the .22 conversion and the unit is functioning excellent. out of all of the .22 f/a guns that i have owned this is the most relaible or at least as reliable as my am180 ! i have owned 3 norrel 10/22, ceiner .22 for my m16, lakeside lm7 for the mi6, fleming .22 conversion for my m10 .45, and this is the best. it is perfect with cci minimags round nose and viper . other ammo depends on power . a few things i have noticed about this unit ; the gun does not get nearly as dirty as any other .22 ! a thousand rounds and it is not as dirty as a 10/22 with 100 rounds thru it . the amount and type of lube is critical. i use slick 50 and it is great.
for the guys that are having functioning problems ; if light primer hits and your timing is correct you might want to take a couple of coils off of the small diameter firing pin spring . it is very stout for a .22 spring even with the g3 hammerspring . remember there are no replacements unless you can get one made so cut slowly. there is plenty of spring so there is no problem plus the pin sets far back from the bolt face so you won't end up with a slam fire. also if you cut some coils off of the .22 recoil spring you may tune it to your ammo, possibly even subsonic. the recoil of blazer .22 rounds etc are just marginal and some times they run well and some times they don't as do other ammo. most of time they will eject but not cycle the bolt far enough back to pick up a new round. this is just do to an underpowered cartridge as compared to the strength of the recoil spring.
after the first of the year i will be working on high cap magazines for this unit. they must be affordable and reliable and durable. any body interested if this project comes about ? i can't give any pictures or details at this time until we see about a patent but if it can be done this should require to go by lots of .22 ammo !
just got back from the range again after putting another 1000 rounds thru my hk51 .22 conversion. i now have put 5000 rounds thru the .22 conversion and the unit is functioning excellent. out of all of the .22 f/a guns that i have owned this is the most relaible or at least as reliable as my am180 ! i have owned 3 norrel 10/22, ceiner .22 for my m16, lakeside lm7 for the mi6, fleming .22 conversion for my m10 .45, and this is the best. it is perfect with cci minimags round nose and viper . other ammo depends on power . a few things i have noticed about this unit ; the gun does not get nearly as dirty as any other .22 ! a thousand rounds and it is not as dirty as a 10/22 with 100 rounds thru it . the amount and type of lube is critical. i use slick 50 and it is great.
for the guys that are having functioning problems ; if light primer hits and your timing is correct you might want to take a couple of coils off of the small diameter firing pin spring . it is very stout for a .22 spring even with the g3 hammerspring . remember there are no replacements unless you can get one made so cut slowly. there is plenty of spring so there is no problem plus the pin sets far back from the bolt face so you won't end up with a slam fire. also if you cut some coils off of the .22 recoil spring you may tune it to your ammo, possibly even subsonic. the recoil of blazer .22 rounds etc are just marginal and some times they run well and some times they don't as do other ammo. most of time they will eject but not cycle the bolt far enough back to pick up a new round. this is just do to an underpowered cartridge as compared to the strength of the recoil spring.
after the first of the year i will be working on high cap magazines for this unit. they must be affordable and reliable and durable. any body interested if this project comes about ? i can't give any pictures or details at this time until we see about a patent but if it can be done this should require to go by lots of .22 ammo !
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915 Posts
Very informative of course, thank You for sharing! What groups do You get out of that conversion, if You don´t mind me asking? Is it comparable to genuine .22s or not at all? Thanks, L.
the receiver is a jld ptr 91 built into a shorty 51 by rdts. the sear is an [email protected] in an sef trigger pack. i picked up a retimed hammer at knob creek just to try it out and it didn't seem to effect the function of the gun in .22 or 308. both calibers run flawless. the only thing about rdts is the wait. it took me 2 years to get the gun and as a pistol it transfered just like any other pistol. then i had to wait on the paperwork for the suppressor to transfer. as i was transferring the suppressor from my dealer to me he brought it to the range for a practice session . we had a baffel torque in f/a in 308 and about 3-4 rounds ended up in the can and none made even a dent ! the dealer sent it back to rdts for repair as it hadn't been transfered to me yet and i am still waiting on it . it has been over another year since return. rdts had new different baffles made . this can is quiet and cheap for a 308 can and it is f/a rated. it just takes forever to get anything from them. i can't wait to shoot the .22 with the suppressor on it .
the groups from this gun are comparable to my 10/22 . i have a red dot on it and it shoots tight with it at 25 yards which is the limit of my indoor range. i have done very little shooting with it on semi and have not tried match ammo in it yet . before i do that i would put a target crown on the barrel . i would not be afraid to hunt squirrels with it but i still might be tempted to put the switch on rock and roll !! whenever i get a chance to not shoot it f/a and take my time i will measure some groups with subsonic match. i don't thing that the barrel is the limiting factor on the accuracy, i believe it is the trigger ! i can get singles out of it on f/a in both calibers but it doesn't have the 2 pound trigger that my suppressed 10/22 has .
the groups from this gun are comparable to my 10/22 . i have a red dot on it and it shoots tight with it at 25 yards which is the limit of my indoor range. i have done very little shooting with it on semi and have not tried match ammo in it yet . before i do that i would put a target crown on the barrel . i would not be afraid to hunt squirrels with it but i still might be tempted to put the switch on rock and roll !! whenever i get a chance to not shoot it f/a and take my time i will measure some groups with subsonic match. i don't thing that the barrel is the limiting factor on the accuracy, i believe it is the trigger ! i can get singles out of it on f/a in both calibers but it doesn't have the 2 pound trigger that my suppressed 10/22 has .
I am about to do this in my PTR 51p PDW and am slightly confused about the full sized recoil spring part. My PTR 51P came with a collapsible and shortened recoil rod/spring, how would you expect this to work on a .22 carrier that has been cut down to the same size as the stock 51p carrier? Is the internal diameter of the 22 conversion different and allow the spring to travel deeper? If thats the case, then wouldnt the spring just push through the carrier and no provide any forward force to close the bolt?
I also just picked up a training bolt i was going to pay to have cut and rewelded. Does the same apply for the training bolt in the 51p? You can just cut it down and not worry about rewelding the endcap?
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