Has anybody ever encountered M70 extraction timing issues? Hoping Chad will chime in.
Gunsmithing M70 Extraction Timing
- Thread starter Undrgrndprdcts
- Start date
Ok, here I am! Blue tights and a pink cape even. 
"Extraction timing" is a little vague I'm afraid as it can mean any number of things. Primary extraction is little more than the helical motion the bolt makes as you lift the handle to cock it while also pulling the cartridge from the chamber. The helical motion comes from what amounts to a spiral ramp. (may help some to think of it as part of a thread on a nut/bolt)
It's either "too gooder" which means the ramp is too far advanced and the bolt lugs are catching on the clearance ramps up inside the action as the cams move it rearward. This would be extremely rare on a Winny as I doubt it would ever leave the factory this way just because it would be so obvious. The more technical term I guess would be too advanced on the timing.
The other is "not so gooder". Here the timing is grossly retarded. The bolt isn't catching a thing till late in the rotation. RR S/N prefix Remington actions are plagued with this very badly. An M70 would have to be seriously "effed" with for it to get that bad. By that I mean someone who went caveman on the bolt lugs/receiver lugs during an accurizing attempt.
That about covers the Primary Extraction feature.
Now, onto the actual extractor:
The non rotating claw extractor WILL snap over a chambered round if single loading. If it doesn't then it was not fitted properly. The chamfer on the lead edge will need to be altered. SMALL MOVES make big differences. Leave the Dremel in the drawer and step away. A file will serve you better.
Next is shell pressure. The case must have a very forgiving entry onto the bolt face. The bottom corner that first engages the case rim should be belled to encourage the case to slide up between BF and the extractor claw. Once it has purchased and positioned the case, the leaf spring behavior of the extractor needs to exert a small amount of force on the case rim/head to keep it there. This is what will get the cartridge out of the gun without it falling out and flopping onto the cases still in the magazine. Again, SMALL MOVES and this should also be a Dremel Free Zone. Shell pressure is a delicate balance and you basically want enough to do the job without being excessive. A high level of shell pressure will cause the gun to "stick" slightly when you run it slowly. It should be be fluid in linear motion when running the bolt. Not having enough "bell mouth" on the bottom of the extractor will do this too so you have to ensure you don't get one tracked in your head and forget about the other related feature/function.
Hope this helps.
C.
I'll change back into jeans now. I'm chaffed.
"Extraction timing" is a little vague I'm afraid as it can mean any number of things. Primary extraction is little more than the helical motion the bolt makes as you lift the handle to cock it while also pulling the cartridge from the chamber. The helical motion comes from what amounts to a spiral ramp. (may help some to think of it as part of a thread on a nut/bolt)
It's either "too gooder" which means the ramp is too far advanced and the bolt lugs are catching on the clearance ramps up inside the action as the cams move it rearward. This would be extremely rare on a Winny as I doubt it would ever leave the factory this way just because it would be so obvious. The more technical term I guess would be too advanced on the timing.
The other is "not so gooder".
Here the timing is grossly retarded. The bolt isn't catching a thing till late in the rotation. RR S/N prefix Remington actions are plagued with this very badly. An M70 would have to be seriously "effed" with for it to get that bad. By that I mean someone who went caveman on the bolt lugs/receiver lugs during an accurizing attempt.That about covers the Primary Extraction feature.
Now, onto the actual extractor:
The non rotating claw extractor WILL snap over a chambered round if single loading. If it doesn't then it was not fitted properly. The chamfer on the lead edge will need to be altered. SMALL MOVES make big differences. Leave the Dremel in the drawer and step away. A file will serve you better.
Next is shell pressure. The case must have a very forgiving entry onto the bolt face. The bottom corner that first engages the case rim should be belled to encourage the case to slide up between BF and the extractor claw. Once it has purchased and positioned the case, the leaf spring behavior of the extractor needs to exert a small amount of force on the case rim/head to keep it there. This is what will get the cartridge out of the gun without it falling out and flopping onto the cases still in the magazine. Again, SMALL MOVES and this should also be a Dremel Free Zone. Shell pressure is a delicate balance and you basically want enough to do the job without being excessive. A high level of shell pressure will cause the gun to "stick" slightly when you run it slowly. It should be be fluid in linear motion when running the bolt. Not having enough "bell mouth" on the bottom of the extractor will do this too so you have to ensure you don't get one tracked in your head and forget about the other related feature/function.
Hope this helps.
C.
I'll change back into jeans now. I'm chaffed.
Excellent info. Let me be a little more specific now. I'm pretty sure the primary extraction is just fine. I'm also not having any issues per say with extraction. This is also a push feed. I guess the timing may not be extraction related at all, but perhaps with the firing mechanism. It has the double click during bolt lift, as opposed to a single click. The bolt will be about 90 percent lifted and at the last eighth inch or so it will click before it completely locks open. It also did this before it was built. Is something wore with the firing assembly? Thanks for your help Chad.
Sharpie up the lugs where they have the little chamfer to clear the clearance ramps up in the receiver. Judging by what you are describing it is catching on the up right before it pops out of battery completely. If it's wearing away on the ink, then I'd give it a kiss with a flat file and broaden the chamfer slightly.
I will try that thank you.
Ok, here I am! Blue tights and a pink cape even.
You know we all went visual on that right?
C.
I'll change back into jeans now. I'm chaffed.
Just a suggestion, Zoomba leggings. They're made just special not to rub. You can get them in many colors to match the cape
Seriously, good information. I've had a lot of Mausers in the past that were sporterised to something and had those issues. Also, my current Winchester push feed in 6.5 Creed does that. I'll look at it from a bolt perspective instead of just thinking it's the brass.
Last edited:
Following up on this. I did check the lug chamfer engagement and it was in need of some clearancing. I did that and it helped smooth it out a lot, however, its only noticeable with the safety on. It still has a click or detent before its fully out of battery when the safety is off. So upon further inspection, it appears there is a worn spot creating a faux detent on the bolt where the cocking piece ramps up. You can see in the pic it stops there temporarily before it gets to the actual detent. This is the final click/hangup I'm feeling in my bolt lift. Not sure on the best way to smooth this out, thinking a light polish with something, although its tough geometry (helical). My other M70's have less of a flat spot/material between the end of the ramp and the detent. This one has a fair amount more.
Attachments
Bumping this up hopefully for some more insight from Chad.
Similar threads
