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6.5x55

19K views 113 replies 17 participants last post by  1biggun 
#1 ·
My dad is a big fan of this caliber and already has several Mausers for it. And brass. :)

We are looking at an AK build in this caliber. According to the small amount of data I can find, the chamber pressure for the 6.5x55 is up to around 46,000 CUP/51,000 PSI. That is around the .308 pressures.

I'm thinking a quick and easy conversion will consist of:

- Saiga .308 conversion $600
- New barrel $250
- COmpliance parts $100?
- Magazine?

The magazine is the stickler on this. Since the cartridge is slightly longer than .308, I am not sure if the .308 magazine will work. I am looking at some different caliber surplus mags in case we need to do a complete magazine conversion. Any thoughts or shortcuts anyone can think of?
 
#33 ·
HC what does a psl handguard look like Any pictures????? I have some odd ball stuff im not sure what it is.
The handguards in this picture... I can get the thumbhole stocks, they are the same as on the WASRs and several are usually FS on the auction boards, but I have yet to see the handguards go up for sale:

 
#29 ·
Interesting discussion. Do you guys think a Romy could be converted to 6.5x55 if light bullets and loads intended for the old surplus mausers were used? My Speer Manual lists 45000 psi as max pressure which isn’t too far from the 43000 I’ve seen listed for the 7.62x39. Still, the mild mauser load data shows a 100 gr bullet at 2800-2900 fps which is right there in .243 Win territory.
 
#30 ·
read all the info in the 308 conversion threads. the chamber pressure is around the same but the bolt thrust will be higher due to the larger rim diamiter. if you keep the pressures down you can likely use a rommy. how ever there is no guarentes with this stuff. there have been 308 winchesters built on rommy bolts and trunions and so far none have failed. any time you excede the maximum bolt thrust of the round that the gun was designed for you are in uncharted territory. I have several conversions and I feel safe with them but I cannot advise others to follow in my path. there is no hard facts on what a rommy or any ak trunion can take. it is known/ reported that a two lug sagia trunion will not pass the european proof tests in 308 win and that is why there is 3lug trunions in those guns. the m77 and 76 uses a two lug that is very simular.

I bumped the 308 conversion thread up to the top of the list so you can find it. lots of info for you to read and base your decisions on
 
#31 ·
Thanks for the info and the bump. I read the 308 thread and have a few more questions. I calculated bolt thrust for both rounds per info in the thread and came up with the following:

6.5x55 (.480 dia) = .181 x 45000 psi = 8145 pounds
7.62x39 (.440 dia) = .152 x 45000 psi = 6840 pounds

I’m not an engineer, but I don’t think it’s this simple. There should be some difference in bolt thrust depending on bullet weight, right?
How about if I rebated the rim on the 6.5? If I turned it down to .440 it wouldn’t lessen the force on the bolt face, right?
 
#32 ·
There should be some difference in bolt thrust depending on bullet weight, right?
How about if I rebated the rim on the 6.5? If I turned it down to .440 it wouldn’t lessen the force on the bolt face, right?

NO AND NO

the bullet weight has nothing to do with it the pressure is the number you use. Now if you were calulating recoil then the bullet weight has a big factor.


as far as rebating or adding a rim it will not change the the amount of bolt thrust. you actualy need to use the inside of the case ID to do the caluclations. think of it this way if you were to jack up your car with a bottle jack and you placed a board under it and had 2000 pound of weight on the board. then placed a smaller board between the jack and the original board you would still have the same weight on the original board. the pounds per square inch would be the differant from board to the other but the total weight would be the same.. ( I THINK I SAID THAT RIGHT IVE HAD A FEW RUM AND COKES AND ITS 130 AM and im no enginere either.LOL)
 
#38 ·
Well I got some of those IMA 7.5mm mags and it looks like they WILL work for the longer 140 grain rounds! These aren't actually the RIFLE magazines with that cool tab - these are the MG magazines! It appears they are 25-30 rounders but I haven't loaded one up completely due to the amount of cosmo in the mags.

I suggested to him not to use .308 mags but rather to use a magazine capable of using *any* 6.5mm round since you never know if we'll ever want to run some service ammo. Need to clean some of the cosmo off so I can do more testing ;)

The .308 magazine will work as-is for his lighter 100 grain loads but are just a tad too short for the 140 grainers. The 7.5mm mags are a tad on the long side, but not long enough to cause the rounds to tip if they slide forward like they do in the 8mm magazine.

These 7.5mm mags also have a last-round BHO tab :)

I'm planning to make floorplates for one US compliance part. They are similar FAL floorplates in that they are simple flat tabs. Since we'll most likely be getting a US-built barrel, that's 5 parts already - floorplates, barrel, receiver, piston, and muzzle brake. If we end up making those handguards (like it looks like we will!) then there's #6!
 
#39 ·
I suggested to him not to use .308 mags but rather to use a magazine capable of using *any* 6.5mm round since you never know if we'll ever want to run some service ammo.
I agree. besides the beauty of the 6.5 is the ability to shoot the high BC bullets like the 147 GR,s that the 1000 yard guys use. You might as well make that thing reach out and touch something if your going to all the trouble. with a good barrel this could be a tack driver. post some mag pic when ever you get a chance. I wonder if a 7mm mauser would fit in one?? HMMMM Im looking for deals on 6.5 barrels for my 260 Remington I pass on any thing I find.

Im researching twist rate for thr high BC bullets
 
#40 ·
There are a few 6.5 barrels on Numrich in the $150 range. They are listed as Mauser replacement barrels. We are planning on the 24" model with that 21" model as a 2nd choice.

A few mock-up pics- remember these are the MG mags, not the MAS mags. I confirmed that these are 25-rounder mags! Using a metal handle to simulate the bolt, I can lock the mag up in the vise's rubber jaws and strip rounds without any tipping problems. The front of the mag lips are a little cramped and can shave the brass some, and so I think I will need to cut them back some to be closer to the AK magazine lip style.




Compared to .308 mag:




I think the challenge on the magazine will be to get the rear locking lug welded up on the back of the follower extension. The bolt hold open on these mags are LONG!

 
#42 ·
If your going with 308 length, then you might want to look at the IMI 308 Galil mags.

HC, you should have a PM.
 
#44 ·
Well nothing, yet. I have several generous offers and I was outbid on the one I was bidding on Gunbroker... only to find out one of my buddies bought it for me! :rofl: He's about to head out of town for a few weeks so I won't be able to actually hook up with him again until around July 4 when he comes over for BBQ. He *claims* he has both pieces so once we hook up I'll know for certain. Otherwise, I'll follow up on those others ;) Either way, we should be all set for the stock before hunting season!
 
#46 ·
Wanted to give an end-of-Summer update! :)

Real Life work basically took away 2 months of my Summer and there's been other things coming up, so I have had very little time this Summer to actually build stuff. I have however been able to make several big steps on this build.

I got the Mauser barrel from Numrich, and fortunately it is already chambered. The Mauser threads are cut short enough that they will NOT interfere with the barrel journal, so no sleeve will be necessary! :) I may sleeve it anyway to hide the threads.



Got the barrel cut down for the barrel components. Found one of those cheap Yugo front-end partial kits and stripped it down. I had to sleeve the end for the front sight, as the Mauser barrel was slightly thinner. This afforded me the opportunity to create an AK-74 style "large" muzzle brake attachment point, and since we are going to use my old PKM flash hider, it worked out perfectly! Attachment will be simple as all I need to do is install the sleeve into the front sight, then press both pieces onto the barrel.




So now the barrel is ready for pressing, and then will I drill the barrel pin and cross-pin holes.

At this point she's ready for the receiver and trunion mounting.

I had a clever idea too - use the Yugo grenade launcher cut-off as an adjustable gas port! I know this has been discussed in the past but we're going ahead with it. I have an idea how to make a "dial" index to set the gas volume.



I am still looking for a PSL top cover, so if anyone knows of one please let me know! I am aware of the trick to weld two top covers together, and would like to avoid that if at all possible.

I'm calculating the US parts to be the barrel, receiver, internals (x3), and will probably make new floorplates for these mags, as I don't think dad's ever going to need more than 4 25-rounders at once :) Actually we are talking about cutting one magazine down to a 5-rounder or making a shim so it will work for hunting season.
 
#47 ·
She's coming together!

I have an issue now that I wasn't expecting. The 6.5 bullet and neck of the cartridge has a small enough size that it isn't touching the feed ramp. Result is that by the time the case gets to the breech, it smacks the bottom below the chamber and all that happens is the bullet gets pushed down into the cartridge and the neck is trashed. I can slowly feed them by hand (no spring) and it seems to work OK. I'm thinking I have enough room to redo the locking lug (welded on) and move the magazine up higher another 1/16" or so. That should keep them from being too low.

The flip side is that the magazine may be fine where it is. It is placed where the bolt hold-open engages the bolt, and the bullets are stripped from the magazine just like a normal AK. If anything the front needs to go up more.


QUESTION: Will it *dependably* feed without a feed ramp? Because I'm wondering when the magazine is moved up so high if a feed ramp is even necessary? I may leave the magazine as-is and try to add a Saiga-style feed ramp to the magazine.




Right after I snapped this picture I installed the PSL rear extension supports for the rear trunion. 2 rivets and a center support to go :)

 
#48 ·
can you raise the edge of the bullet guide with some weld? i do that on my 7.62x39 builds to get the soft point bullets to feed better. I move the very edge back as far as possable and raise it with a little weld. lowering the mag will make the bullet tip raise up higher as it goes over the guide because it causes a steeper angle. you can only raise the ramp so high or the bolt will hit it. try holding the mag in by hand slightly lower and see if it will help. its hard to get the mag high enough to be a straight shot as it will hit the bolt and carrier.

I really like what you have built so far
 
#54 ·
can you raise the edge of the bullet guide with some weld? i do that on my 7.62x39 builds to get the soft point bullets to feed better. I move the very edge back as far as possable and raise it with a little weld. lowering the mag will make the bullet tip raise up higher as it goes over the guide because it causes a steeper angle. you can only raise the ramp so high or the bolt will hit it. try holding the mag in by hand slightly lower and see if it will help. its hard to get the mag high enough to be a straight shot as it will hit the bolt and carrier.

I really like what you have built so far
I'd never considered lowering the mag - I've been thinking that I'd have to essentially build w/o a bullet guide. I'll have to fiddle with it. It looks like when I move it up on the front it tends to make the bullets dip down in the magazine a little, but I didn't get very far as I've been away on business and kind of sat it all aside.

The good thing is that the locking lugs on the mag are like a FAL - lug on the front (easy weld spot) and a filed notch on the back. Plenty of meat there and it locks up very snug.
 
#52 ·
Pookie I have a 308 saiga thats been converted already to P.G. config. I still have the box . Its got an ace fixed stock tapco trigger and piston. has less than 100 rounds through it. $600 plus shipping will take it. This offer to Pookie only right now, for all the things i've learned from his posts. thanks Chief
I am in Texas
 
#55 ·
Well I broke my mill and my lathe, so I'm done for the night! :) Actually I've been waiting for the gears in the mill to finally give out, and now I'm going to swap in the metal gear replacements. The belt on my lathe broke and for some reason I didn't buy a spare... DUH... so I can't finish the bolt extension.

This weekend I've managed to get the bolt carrier extension working, and drilled the axis pin holes. The spot welding apparently hardened the steel more than I expected, and it took half last night to drill four freaking holes! :( I don't have to harden these pin holes :)

Let's see... fixed up the adjustable gas block, got the bipod extension in place and it works! Finally got the rear trunion rivited and managed to get this WASR stock to fit much better by milling down the inside part enough to make it slip deeper into the receiver... not so much of a stretch now. Still needs fitting but I'm going to let dad do the final fit for his hands.

I'm going to finish the bolt extension and make a longer firing pin then I'll be able to test fire it! I'm going to do the center support PSL-style, with a last-round bolt catch.

Latest pics at the bottom:

http://pookieweb.dyndns.org:61129/6.5x55/6_5x55.htm



A question - would a Galil carry handle attached to this thing look "stupid", or would it enhance the function? I'm looking at pics of some of the world's sniper rifles and think a folding carry handle would be a nice touch.
 
#57 ·
Actually I already have the gears, I bought all the metal gears expecting the "next" gear breakage. SO I should be good now with all-metal gears except that one on top that meshes to the motor gear. I think that one's going to stay plastic so if something breaks at least it will be easy to get to! :)
 
#59 ·
SUCCESS!!! :cool:

The magazines feed. The feed lips had to be bent further to prevent the rounds from popping out too soon. I was able to successfully fire 8 rounds with no feed issues. Now I need to replicate the feed lips on the other three mags.

In these pics, the modded mag (bottom one) is the one that works. Note these are 100 gr rounds, not the factory default 130 grain rounds, so they are a little shorter! These are the only pics for now, I need to snap pics of all my other mods to close the loop. I have yet to weld the top cover extension so no glamour shots yet ;)

The main items on the magazine conversion are:

1. Bend the rear of the feed lips down some to bring them in closer to center, thereby making them touch more of the case.

2. Bend the front of the feed lips down to make them slightly longer against the cases. At the point I bent, the rounds just begin to enter the chamber. This should prevent stovepipes since if they do pop out, the tip will already be inside the chamber. More testing is warranted, I may need to make them even longer just for some extra insurance.

3. Bend the front of the magazine out to elminate the excessive side-to-side motion of the rounds as they are stripped away. I'm not sure how these 7.5 mags originally fed, but they simply can't work in an AK with all that side-side motion.

4. Cut away the sides of the very front of the magazine body and of the follower to allow clearance for the locking lugs.


YES the magazine metal is thin and therefore not as robust as your standard AK mag. I used needlenose pliers for practically all of the bends. You could step on one and bend it. However for my dad's application it is adeqaute since he doesn't plan to do any rugged "work" with his rifles :) I suppose you could weld another layer of metal onto the the sides for reinforcement but honestly I don't think it is necessary.




 
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