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27 rounds of HMR was all it could take.

4K views 52 replies 12 participants last post by  SwampF0X 
#1 · (Edited)
Here's a pic of my converted .22 lr. Hopefully it will show. Sometimes it is the little red X.


Looks like a factory 10/22, no? It has a Chief Dave type 2 style of conversion. To this I added a factory .22 mag barrel, but all other components were still lr. After shooting 100 rounds of mag ammo through it with no stovepipes, FTF, feeding problems, or case head bulging, I felt that the conversion was a success. So it was time to try a hummer. After reading the instructions from Brownells, I thought I would try to line a lr barrel. This was an adventure in itself. If anyone's interested I can post a write up, but it will be long. The main problem in making the barrel was reamer chatter. That means that I wound up with a rough camber. After finishing the barrel, I fired 9 rounds of CCI hollow points to be sure that it would function. It worked with a little case head bulging so I ordered a .22 mag handle and spring for it. I installed the base/scope and thought that I would rough sight the scope in so when at the range the hits would at least be on the paper. Since the CCI seemed to work ok with the lr handle I didn't think that a few rounds would hurt anything. I picked up some Federal V-Max just to try some different rounds through the rifle. It shot the first magazine fine. On round number 24 the bolt didn't close completely. The reason was round 23 had taken the extractor out and the spring/plunger was holding the bolt open. I think that it jarred the extractor out as the case was dented very badly but was not ruptured, it sounded the same as the others, and the bullet impact was in the same area. I just removed the spring/plunger and was going to finish the rest of the magazine. After the last round when I moved my hand I felt something with my thumb and looked down to see this.





It looks like the buffer pushed on the stock hard enough to break it. At this point I thought it was a good time to stop. At home I stripped the rifle and checked the receiver for damage or cracks. The receiver appears to be ok, but I found these marks on the trigger assembly.





These were not there when shooting with the .22 mag ammo. It seems that the bolt is really bouncing around in the receiver with the HMR. Will the mag handle and spring stop this or is there something else going on?

Here is a pic of the fired rounds.



L to R: .22 mag, .17 CCI, .17 Fed, and #23

Reversed in the next pic



Here's a pic of the .22 mag beside the "Factory" .17 barrel.



What an adventure this little project has been.
 
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#27 ·
It is the Magnum Buffer kit from Weaponkraft. It is the standard orange buffer with an extra square pad that sticks to the rear of the receiver. In the true magnum rifle the pad goes behind the orange buffer. In the LR conversion you have to either cut the pad or cut the buffer as there is not room for both. I went Skeeter's route and installed the pad then cut the buffer in 2 pieces. These pieces slip in and touch the pad on the receiver. They are held in place by the stock. The theory is that you get the benefit of the orange buffer, the buffer has some room to expand when mashed by the bolt, and the pad helps to cushion the blow to the receiver.
 
#28 ·
i cant belive youre still having some problems-ive never had any of those problems with my wmr conversion but then again ive never tried hummers out of it yet either-we'll get this figured out for you,i dont know if skeeter has had any problemswith hummer either.......
 
#29 ·
Gunter, this is just my opinion, but lose the pad and go back to a single uncut Buffer. Firstly, all the pad was ever intended for was to bridge the gap between the Buffer and rear receiver wall in a Magnum receiver. Used with the LR receiver, and even with your mod, it could inhibit full bolt travel, and was never intended to directly take the kind of pressures you're subjecting it to. It's only Nitrile, not urethane, so it doesn't have the same "capabilities" as the Buffer.
What happened when your stock broke was a total fluke.
It's the only time I've ever seen it happen, and I'm virtually certain it only happened because of the mismatch between the round you were firing and the Recoil Spring you had installed at the time. .17HMR vs. .22LR spring, wasn't it? :eek:
Guys, I don't even claim to begin to fully understand all of the subtle nuances of the LR to MAG conversion, but I'm pretty sure that I do get this part. :D

FWIW! ;) - Dakotan
 
#31 · (Edited)
Tack... I think that as a WMR it will do just fine. I shot 100 rounds of WMR without losing an extractor, or busting the stock, and that was with the LR handle/spring (which you should never do if anyone else is thinking of this conversion. Use the heavy recoil spring and hammer spring). As a hummer it looks like I'll have to install an extractor every 20-25 rounds. IIRC you fired the barrel while you had it? How did the cases look with your rifle?

Dakotan... No problem. I have a spare buffer from you. I was going to replace the pad anyway.

Thanks for the input. Maybe Skeeter or Chief Dave has a clue whats going on. I'm wondering if it could be the barrel. Maybe the liner is to small, however the reamer pilot fit perfect. I did moly the liner after the install, but made a fired case into a sleeve and glued it in the chamber while doing the moly. I didn't want the chamber to be molyed with the LR conversion. I don't know.

I may just have to leave it as a WMR and buy a bolt rifle for all the hummer ammo I have now. :D

P.S. How much would a .250" x .5" long rod of Tungsten add to the bolt? I came up with a little over 1 ounce when subtracting the weight of the steel being drill out. Is that right or did I mess up the math?
 
#32 ·
Triple slug

I think you are correct. If you triple slug the barrel, and confirm its profile, I think you may find it to be too tight.
If it is a liner from Brownell's, it may be as much as .006-.007" too tight. That is the only thing that I can see from here that would not allow you to see the benefit of Tack's porting job=The pressure is still not being relieved soon enough/more pressure is being captured. I have not done a barrel liner myself, but I remember TFrank making comment to me that he needed a special pilot on his chamber reamer, because an SAAMI chamber reamer's pilot would not fit into the bore of the liner.
You know how to triple slug a barrel right? The great thing here, is you can use .177 lead pellets for this. :t
Should only take a coupla minutes to do.
One more aspect that you should verify, is that your liner was in fact a 1:9 twist liner, and not accidently a 1:10 twist liner. A 1:10 liner could also create the increased resistance/pressure.
Keep us "Posted". :t
 
#33 · (Edited)
Best as I can remember the difference with the pilot is the Redman pilot is .166 or.1665 and the std reamer is .167. Clymer's site is down right now and I can't find the prints of the reamers that I printed out.

Tack's porting did help alot with the recoil. When I say that the bases have a slight dome now, I mean a slight dome. They set flat and if you didn't have an unfired case to compare it to you might not notice it. Big improvment over the cases fired without the ports.

I slugged the barrel and the pellets that I used might not be the best to try to measure. I measured the head of the pellet, the base, and in the rifling grooves. The chamber and muzzle slugs were 1 inch from each end.

Chamber Mid Muzzle
Head .171 .171 .171
Base .172 .171 .171
Groove .167 .167 .166

I didn't check the twist rate as I couldn't find the 17 mop so I could use the coated rod. Kinda hard to measure with the boresnake. It's one of those days.... can't find s@#t.

So without the specs, I'm guessing that the bore is too small? That would explain why Tfrank is still having trouble with his Mossy .17Agulia even though his bolt is weighted to the EABCO Mach 2 conversion.

The liner was what I would call a good slip fit. It would slide in with just hand pressure. It didn't fall through nor have to be beat in with a hammer. If I squeezed the liner I must have done a good job to keep it within the specs posted above. If it is too tight, then why the crap doesn't Redman and Brownells tell you that they might be to tight for semi-autos? The main reason I did the liner thing was for the experience, but I would have liked to have a usable barrel when finished.

I mic'ed one of the CCI bullets right at the crimp and it shows to be .170.
 
#34 ·
After searching for 2 days on the web for the bore spec, I posted it in the HMR fourm and they said that the bore was right on at .171". So if the liner is the problem then it would have to be in the thickness of the rifling. Which should be .002" according to the slugs.

Thinking about ordering some HD Tungsten rods for inserts in the bolt and making a stiffer hammer spring.
 
#40 ·
Anouther place to look is a good golf component site. They will have an excellent choice of tungsten plugs and also one item I have used for loose barrel fits is micro glass beads mixed with epoxy.These beeds come in different dia.'s and if the fit is sloppy choose the size you need and mix with your favorite epoxy. These were designed for golf shaft fits and will take a pounding.
Ten Ring
 
#43 ·
I don't think a single hole would be enough, because the diameter of the hole is restricted by the fireing pin. Also the metal being removed by drilling is heavy already. What you put inside needs to be as heavy as possible and should IMHO go all the way through. The set screw would weigh less than the material removed for it, so it would defeat the purpose. This is my opinion only, I have no figures to back it up.

BTW Tack, Did you get those barrels yet? Also are you capable of fluting the heavy bull .17 aug? Sorry I keep popping more work on you. If you can't that's okay. I would like to lighten it up as much as possible. Maybe you could turn it down like a running boar and sleave it like we discussed on the pistol barrels? THEN port it per skeeters instructions??????

If I become annoying with all this crap just let me know. I know I keep changing my mind about stuff and If anything becomes unclear just let me know.

thanks,
swampf0x
 
#44 · (Edited)
Tack - I don't see why you couldn't thread the rod and tap the bolt. Other than needing a bottom tap.

Swamp - The tungsten rod is from McMaster-Carr and is around $40 for a 1/4 x 8 long rod. The company I work for has an account so I just bought it from them. There is probably some place that sells it cheaper.

Ok now this is just from info found on the internet plus I had to change it from g/cc to something I could understand. :D If I did the math right this should be the amounts for 1 cubic inch of material:
Steel = 4.6 ounces
Lead = 6.5 ounces
Tungsten = 11.1 ounces

Since steel is about half the weight of tungsten, you will lose about half of the weight of the tungsten to replace the steel you remove.

The plan is to drill the bolt with a carbide bit to a set depth and then plunge mill the bottom of the drilled hole flat. Or if the carbide bit doesn't cut it then just plunge mill the hole. Then epoxy or green Loctite the slugs in place. Going .350 into the bolt might be removing a little to much.
 
#45 · (Edited)
Good info gunter. Please keep me updated on your progress with this.
But why not drill less holes and make them deeper??? Would probably help to keep the bolt balanced on both sides.
Isn't 1.5 oz heavier the magic number we want to achieve? Maybe I'm thinking of something else but I thought the magnum bolt was 1.5 oz heavier than the lr bolt. Maybe I've got this and the mh2 conversion mixed up, I dunno. Anyways good luck and keep us posted.

swampf0x
 
#46 ·
I think the Mag bolt weight is around 16 ounces and the LR is around 6.5 ounces. That is from what little memory I have left.

The EABCO handle is supposed to add 1.6 ounces of weight for the HM2 to bring the LR bolt to 8.1 ounces.

I don't have the bolt here but I think that the smallest point on the side of the bolt was from the firing pin roll pin to the bottom of the bolt. Seems it was like .390 or so. That's where I came up with the .350 deep hole for the slugs. Someplaces you could go deeper. I Guess I should also measure going in from the side of the bolt and see which way would give the most possible weight gain. When I get the stuff here I'll cut a .250 piece off and weigh it to see if the figures are right.
 
#48 ·
Hal you are correct. I forgot to square the radius. Once I had the ci for the size I just used it to figure all of the weights. So that means that all of the weights I posted are way off. Sorry guys. It's been a while since math class. When I get the stuff here I'll weight it and post what it is. Going to edit the other posts. Again sorry for the mistake.
 
#49 · (Edited)
I received the high density tungsten ¼” tungsten rod yesterday. It measured 8.125 inches long, so if the figure from the net was correct then it should weigh 4.4 ounces. I slapped the rod on the scale and it was 4.4 ounces, which it looks like it was right on the money. I weighed the bolt again to be sure and it was right at 6.5 ounces. After looking and doing some thinking it looks like going across the bolt would be better than going in from the bottom. I should be able to install four slugs across the bolt and miss the firing pin slot and cutout for the recoil rod. Doing it this way allows for .171 cubic inch of tungsten instead of .154 for the nine slugs in the bottom of the bolt. If I did the math right again that should be 1.89 ounces minus the .78 ounces of steel that will be removed for a total weight gain of 1.11 ounces. Hal check my math again to be sure.

Did I read here on the forums that someone was selling the EABCO handle by itself?
 
#50 ·
Gunter:
Your latest numbers look good. For every cubic inch of steel you replace with tungsten, you should gain 6.5 ounces of weight. That is based on your original density figures of steel @ 4.6oz/cubic inch vs tungsten @ 11.1 ounces/cubic inch.
So, if your planning to gain weight by replacing steel with tungsten, just multiply the cubic inches by 6.5 to figure the weight gain. That's the difference between steel and tungsten.
Let me know how this turns out. It took two shots for me to stop a four or five pound jack rabbit this morning at about 65 yards and I'm not happy. First shot broke it's back (side shot, over estimated range), second head-on in the boiler room. Need more power. I used Win Super X hp and an 18" A&B barrel rig w/Redfield 3x9.
I'm thinking .22Mag or .17HMR. They should be good for 100 yards plus, which is over the fence.

As an aside, if I could get a permit, I could probably get a pronghorn with a 20 guage slug this fall (buckshot is not legal).
 
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