24hourcampfire.com
24hourcampfire.com
Previous Thread
Next Thread
Print Thread
Hop To
Page 1 of 2 1 2
#16861028 01/20/22
Joined: May 2019
Posts: 445
OXN939 Offline OP
Campfire Member
OP Offline
Campfire Member
Joined: May 2019
Posts: 445
AK guys, got one for ya. Have a Century M70 underfolder that is currently a single shot. It fires, extracts and ejects fine, but stops about a half a centimeter short of returning fully into battery when chambering the next round. I've taken it to one smith who "dug at some carbon buildup in the gas system with a dental pick" which didn't do anything. I hit the gas system with brake cleaner, which appears to make its way through the gas port into the barrel, discrediting that smith's idea that an occluded gas system could be the issue- further, there is no issue with extraction or ejection, so it doesn't seem that being undergassed is the culprit. It does this with three different brand new mags and at least two kinds of ammo.


Where the bolt stops:
[Linked Image from live.staticflickr.com]


Top down view of receiver, in case anyone can find something I missed:
[Linked Image from live.staticflickr.com]


Could it be that I just need a new recoil spring? Not seeing any obvious burrs or anything out of the ordinary on the receiver. Any input is big time appreciated- thanks in advance!

Last edited by OXN939; 01/20/22.
ARIC

Joined: May 2019
Posts: 445
OXN939 Offline OP
Campfire Member
OP Offline
Campfire Member
Joined: May 2019
Posts: 445
One more addendum- if I rack the bolt and then ride it back down, I can get it to hang up about 20% of the way forward as shown below:

[Linked Image from live.staticflickr.com]

I don't seem to recall being able to do this with other AKs I've used. With the dust cover removed, I can release the BCG fully forward from this point by raising the safety to "above safe." It's also got the TAPCO trigger. Thanks again for any input!

Joined: Sep 2001
Posts: 18,941
M
Campfire Ranger
Offline
Campfire Ranger
M
Joined: Sep 2001
Posts: 18,941
It would seem that something is binding.

I'd take it apart and inspect closely for finish wear on the metal, to work out where it is happening.

Joined: May 2019
Posts: 445
OXN939 Offline OP
Campfire Member
OP Offline
Campfire Member
Joined: May 2019
Posts: 445
Originally Posted by MontanaMarine
It would seem that something is binding.

I'd take it apart and inspect closely for finish wear on the metal, to work out where it is happening.


No indications of binding I could see. Would imagine you'd be able to see them from the viewpoint of that second photo if that were going on

Joined: Jan 2005
Posts: 57,366
R
Campfire Kahuna
Offline
Campfire Kahuna
R
Joined: Jan 2005
Posts: 57,366
The binding should show as wear spots. Pictures may not even come close to showing that.

It worked new? And fires if you force feed?

How hard is it to force it that last bit?


We can keep Larry Root and all his idiotic blabber and user names on here, but we can't get Ralph back..... Whiskey Tango Foxtrot, over....
IC B2

Joined: May 2019
Posts: 445
OXN939 Offline OP
Campfire Member
OP Offline
Campfire Member
Joined: May 2019
Posts: 445
Originally Posted by rost495
How hard is it to force it that last bit?


Not tough. Been a minute since I've run it, but I'm pretty sure if you rack it manually it chambers and goes into battery just fine.

Might try a different BCG/bolt and see if that helps?

Joined: Jan 2005
Posts: 57,366
R
Campfire Kahuna
Offline
Campfire Kahuna
R
Joined: Jan 2005
Posts: 57,366
id say its binding on something up front and you should see the wear. Similar just found on a brand new smith revolver. Look at the area of hammer with flashlight and it was obvious where the issue was and needs relieving.

You could try different bolt I suppose but I"m not familiar at all with AK stuff

I'd surmise could be a weak recoil/return spring too assuming it works manually all the time.

Oil is never a bad thing either. Lube makes supposed issues go away quite often.


We can keep Larry Root and all his idiotic blabber and user names on here, but we can't get Ralph back..... Whiskey Tango Foxtrot, over....
Joined: Nov 2011
Posts: 30,594
A
Campfire 'Bwana
Offline
Campfire 'Bwana
A
Joined: Nov 2011
Posts: 30,594
Look at the interface between the bottom of the bolt and hammer. You may need to smooth these out with some very fine sandpaper, perhaps something around an 800 grit.


You didn't use logic or reason to get into this opinion, I cannot use logic or reason to get you out of it.

You cannot over estimate the unimportance of nearly everything. John Maxwell
Joined: Jul 2015
Posts: 14,570
Campfire Outfitter
Offline
Campfire Outfitter
Joined: Jul 2015
Posts: 14,570
I'm PM renegade50 about this. That guy is ate up on AKs.


Politics is War by Other Means
Joined: Nov 2006
Posts: 10,713
C
Campfire Outfitter
Offline
Campfire Outfitter
C
Joined: Nov 2006
Posts: 10,713
Originally Posted by Tyrone
I'm PM renegade50 about this. That guy is ate up on AKs.



Agreed. Rene is the AK /comblock guru here.


Mathew 22: 37-39



IC B3

Joined: Sep 2001
Posts: 18,941
M
Campfire Ranger
Offline
Campfire Ranger
M
Joined: Sep 2001
Posts: 18,941
Seems likely there is a binding when the bolt locking lugs are rotating to lock into the trunnion.



Joined: Jan 2012
Posts: 45,002
R
Campfire 'Bwana
Offline
Campfire 'Bwana
R
Joined: Jan 2012
Posts: 45,002
In response to your pm man and for others to possibly benefit from
It is the hammer and its pronounced ridge on it.
Hammer bump/ drag.
It is what is causing the hang up in the rear when you cock it at times
And is slowing down the carrier assembly both going backwards and forwards when firing.
The hammer is cocked into place by the mating surface plane under the carrier.
If you dig back in my post history on this forum several yrs ago .
Another member had the same issues with a WASR 10.
Another century arms imported 922r compliant gun they sell.
Century gets various styles of hammers/ trigger mechanisms and uses them willy nilly with vastly different hsmmer bump profiles.
They will assemble x amount of guns with what ever .
Then use next sourced parts on another run until out.
It is basically a tolerance stacking issue from not using matched parts in the century arms system.
Your hammer bump profile is extremely high and sharp.
The rest of the trigger assembly is a single hook design which century installed.
Most m70 series have a double hook design
The " hooks" are what keep the hammer withheld in the cocked position on each of the wings of the hammer.
Their are dozens of vids on the web you can google to fix the problem from a simple gentle contouring of that pronounced edge bump and a polishing of trigger components.
Another issue century has is hard hammers versus bolt tail and carrier tail peening due to components not being same sourced and heat treated/ harden properly for each other.

Another option is a after market replacement trigger or just a replacement hammer with a rounded over profile hammer .


But you can google fu this stuff and address the problem if you are comfortable doing the work yourself and get that wpn running correct.

That tutorial is in this forum with pics.
I think it was Antelope Sniper that had the same problem you have.

Joined: Jan 2005
Posts: 57,366
R
Campfire Kahuna
Offline
Campfire Kahuna
R
Joined: Jan 2005
Posts: 57,366
Thanks for adding the post with help. Hopefully it helps more that have AK problems.


We can keep Larry Root and all his idiotic blabber and user names on here, but we can't get Ralph back..... Whiskey Tango Foxtrot, over....
Joined: Jan 2012
Posts: 45,002
R
Campfire 'Bwana
Offline
Campfire 'Bwana
R
Joined: Jan 2012
Posts: 45,002
It is a common issue with older century 922r guns they brought in.
Too many sourced parts installed not originally designed for the specific gun.
They " fit"
Then when used up move onto the next batch of parts they had from where ever and make more.
Tolerance stacking basically and geometry problems in the train.
Can be addresed various ways by the end user or thru aftermarket.

Century was infamous for this stuff.
Just throwing it together and sending it out.

It plagued the WASR,s and the Yugo,s century put out back when.


Any other of you guys looking at AK,s or AKM,s
Please stay away from century guns as a whole.
JMO....
WASR,s post 2013 are good guns for a entry level AKM.
No one is gonna snicker at you about a WASR if they know about the manufacturing and proper components of the platform.

Have someone go with you that knows how to inspect a AK or AKM
for proper assembly front to back.
And preferably inspect 2 or 3 of em and pick the best one
Buying sight unseen online is a crap shoot.
You get what they send and might think what they send is normal.
You might get one gun selection at LGS that is GTG or it might have alignment issues in its components.
You can educate yourselves with vids.
How to inspect a AK/AKM vids will help alot and save headaches later on.


You all have a good weekend.

Joined: Jul 2015
Posts: 14,570
Campfire Outfitter
Offline
Campfire Outfitter
Joined: Jul 2015
Posts: 14,570
Thanks Ren!

As usual, you are a fountain of knowledge of these. It was a pleasure reading your post.


Politics is War by Other Means
Joined: Jan 2012
Posts: 45,002
R
Campfire 'Bwana
Offline
Campfire 'Bwana
R
Joined: Jan 2012
Posts: 45,002
While Im down here with you guys.
With the current import license fiasco by Joey for under the radar gun control stunt he pulled last fall, and then possibly the licenses still in effect not being renewed in the future.
Honk for Joey.....

Palmetto is supposedly ramping up for production based on Tula
Stuff, gonna be pricey and it probably aint gonna fill the void over historical amounts.
Palmetto might tighten up consistency with their stuff they produce or might not
Tula at best has been 4 to 6 moa ammo and more at times.
Large standard deviation from 35 to 50 fps in tula.
It goes bang.
And in this day and age it is priced the same as better ammo for the most part.

AK ammo is like .22 rimfire ammo .
Find what the gun likes
And seek the low SD stuff

3 brands readily available all made by Barnual have SD,s in the mid teens down to 9 Fps which is pretty friggin good in mass produced steel case ammo.
They have consistently been 2 to 4 moa loads at 100m off bench and bags with some mods done to the iron sights that work for me in AK,s and AKM,s I have owned or own now.

Wolf 123gr Hp polyformance
Barnual red and green bx 123 gr Hp laquer
Monarch 123gr HP laquer

For comparable money to Tula .
1 buck or more at most sometimes the same for better accuracy, consistency, and reliability.

IMO and YMMV based on what your gun might like.

Joined: Jan 2005
Posts: 57,366
R
Campfire Kahuna
Offline
Campfire Kahuna
R
Joined: Jan 2005
Posts: 57,366
Good info on the ammo..
That said over the years for the short ranges an AK is typically used I"ve found that ammo SD/ES really isn't the foul in inaccuracy. Typically its a junk projectile.

Be interesting to see if one made Mexican match out of Tula and substituted a known good bullet if it changed accuracy.

Only own one AK. Its poly. Somewhere in the back. Haven't seen it in years. When I feel the need for the X39 again I'll buy an AR upper.

Again thanks for sharing the knowledge. Thats stuff that many are happy to see


We can keep Larry Root and all his idiotic blabber and user names on here, but we can't get Ralph back..... Whiskey Tango Foxtrot, over....
Joined: Jan 2012
Posts: 45,002
R
Campfire 'Bwana
Offline
Campfire 'Bwana
R
Joined: Jan 2012
Posts: 45,002
Like you said bullet design has alot to do with it also.
Shot the 123 hornady Sst
50rd bxs
Accurate
Pricey
Lotta euro brass case and copper jacket bullets versus bimetal jackets out their also that are accurate.
S&B
Privi
Yugo M67
Others also..

Accurate but pricey.


I think aotta the hardness of bimetal jackets in relation to rifling is like a mouldablity issue to them kinda skipping longitudinal across lands.
Espeically in the leade area and 1st inch or 2 of the rifling before taking "hold" for spin.
Kinda conjecture my part.
But I have looked at alot of ak,s and akm,s where they leade is not a nice visible ring and it looks basically like a overly long shotgun forcing cone going into the rifling.
Some look relatively VG exterior and mech wise.
Then ya look down the barrel.....

Not cleaning , running too hot and mag dumps can do this also.
I think bimetal plays into it also as a factor.
But cleaning alleviates bi metal barrel wear issues IMO.

# of factors come into play.
Build up of and erosion issues of bimetal can be addresed
And then ya throw corrosive ammo issues into also.

Perfectly good wpn neglected is no longer a perfectly good wpn.

You can deliberately screw up and destroy just about any mil type wpn firing a obscene amount of ammo thru it in a short given time.

Tracers rds are the worst and take the least.
Reemed out many an azz over the years, soldiers trying to do the full tracer mag thing mag after mag after mag auto and semi...
Just cause they thought it would be cool and could get away with it.
🤦‍♂️🤦‍♂️🤦‍♂️🤦‍♂️
Only person in a platoon with more than a 4 to 1 ratio should be the wpns squad leader.
Full 30 for intial mag to desg tgts to his guns.
Then 2 to 1 rest of his mags guns know its him desg tgts and the line sqds from his firing sig.

Everyone else on 4 to 1 if needed, top 2 tracer with last 3 to sig your getting close to reload.

Joined: Oct 2008
Posts: 18,157
R
Campfire Ranger
Offline
Campfire Ranger
R
Joined: Oct 2008
Posts: 18,157
Alg elite


TRUMP- GABBARD 2024
Joined: Aug 2012
Posts: 2,420
Campfire Regular
Offline
Campfire Regular
Joined: Aug 2012
Posts: 2,420
I have a Saiga 308 that often failed to chamber brass cased rounds. The bottom "canoe" of the bolt carrier was rough, and it seemed to be slowing things down as it rubbed on the top round in the magazine on its way forward.
Once the canoe hull was smoothed with wet n dry fine paper and a ceramic hone it learned to love the sliding kiss of American brass.

Page 1 of 2 1 2

Moderated by  RickBin 

Link Copied to Clipboard
YB23

Who's Online Now
202 members (257 mag, 12344mag, 300jimmy, 10Glocks, 300_savage, 2UP, 17 invisible), 1,539 guests, and 865 robots.
Key: Admin, Global Mod, Mod
Forum Statistics
Forums81
Topics1,187,592
Posts18,397,917
Members73,815
Most Online11,491
Jul 7th, 2023


 







Fish & Game Departments | Solunar Tables | Mission Statement | Privacy Policy | Contact Us | DMCA
Hunting | Fishing | Camping | Backpacking | Reloading | Campfire Forums | Gear Shop
Copyright © 2000-2024 24hourcampfire.com, Inc. All Rights Reserved.
Powered by UBB.threads™ PHP Forum Software 7.7.5
(Release build 20201027)
Responsive Width:

PHP: 7.3.33 Page Time: 0.131s Queries: 15 (0.002s) Memory: 0.8995 MB (Peak: 1.0564 MB) Data Comp: Zlib Server Time: 2024-03-28 10:11:35 UTC
Valid HTML 5 and Valid CSS