Extraction diagnosis Sendero

[snert]

Tomorrow a buddy is bringing his early Sendero in 7mm Mag over for me to take a look at. He says that with new factory ammo, and with reloads, the rifle has suddenly developed a case of extraction difficulty. The bolt will lift but then stick about a "scooch" from releasing and it takes a hard lift and a whack with a wood stick to break loose the bolt/case.

I am thinking some foriegn matter in the lugs. Your thoughts as I start taking it apart and looking? (It will cycle live fresh ammo easily).

Get me on the right path here guys...

 

[liljoe]

Corrosion in the chamber maybe.
Joe

 

[Walt Krafft]

You are on the right track with a complete cleaning.

 

[spitfire_er]

Deleted comment, I see you mentioned happens with new factory too.

 

[drover]

A good cleaning is not a bad start but if he is having to "whack" the bolt handle with a piece of wood to get the bolt to open I doubt that a dirty chamber is the issue.

I see that he told you that it happens with factory ammo but I would confirm that before starting to look at other things. If it isn't happenig with the factory ammo then he likely has a high-pressure reload issue.
If it truly is happening with factory ammo then ascertain if it is a new lot number or if he has used some from the same lot with no issues in the past.

The only times I have seen issues like this have been from overloads or a rough chamber, which should have shown up before not just of the blue. Another cause could be brass that was fired in an oversized chamber and has developed a "memory" and does not shrink enough after firing - but if the problem is truly there with new brass then this is not a likely cause.

drover

 

[snert]

Thanks guys...you are all saying what I was thinking. Just wanted to make sure I was not missing some esoteric malady that if caught and fixed would make me look like a gun geeenie-us

 

[jepp2]

(It will cycle live fresh ammo easily).

Sometime back I read someone that said "I never close the bolt on a live round in my shop). I immediately adopted that philosophy.

Removing the FP assembly will insure you don't have a regrettable moment.

 

[PigButtons]

I've had this problem before getting a bore scope to see the carbon ring. Enough of it and it can have a vice grip on the case neck. Comes on all of a sudden without other symptoms. If ignored it will lead to pressure signs as the neck ends up not being able to open properly to release the bullet normally. Thank God for cheap bore scopes.

 

[Coyotefurharvester]

Takes a minute to pull the pin/spring(paracord and a dime in a pinch), first thing I do for any brass fit, bolt function issue. Safety first.

 

[snert]

UPDATE:

I got a look at the rifle. Cutting right to the chase, I didn't fully diagnose it because when I looked at it the bolt handle was loose (braze giving way to getting smacked to open). However, I measured his fired cases at just in front of the belt and there was a .001 difference between one time and many time fired. Nothing hugely odd.

I checked the chamber. Small amount of carbon ring, and lotsa junk in the lug recesses. I also noted some peening on the bolt face edge from an over long action screw. That appeared old damage.

I tore down the bolt and cleaned it. I scrubbed the crap outta the chamber and lug recesses. I got most of the carbon ring out. I filed the action bolt enough to shorten it up. I also faced the little peen on the bolt- face with a stone. The rifle is soaking now overnight after some serious bore cleaning. Lots of brushing and some jusicious JB cleaned it up pretty well. It is still showing blue when I use Wipe out and I can see some carbon in the rifling. None of that speaks to the extraction issues though. I will return it to him clean. I also cleaned the trigger. Lots of rounds thru this old bird.

I am wondering if there was just enough guck in the lugs etc to stack tolerances.

I noted nothing out of the ordinary on the extractor or the cases.

It will go to Dave Bruno for a check up and bolt fix.

I had forgotten how nice the first gen Sendero rifles were.

I will report when we get a definitive answer. BTW, I did not chamber anything, loaded or not, due to bolt handle issue.

 

[Dusty Stevens]

The carbon at the case mouth and chamber finish would be my guesses. Once the bolt handle is fixed id take a look at that

 

[AlNyhus]

........when I looked at it the bolt handle was loose (braze giving way to getting smacked to open)

Boy...that's a new one on me. Normally, a 700 bolt handle is either on or off !

Hard to diagnose 'long distance' but if it's actually loose...you've found the extraction issue as you're loosing primary camming during extraction.

As mentioned earlier, I'd really get after the carbon build up. Those 7 Mags can really lay it down in there right ahead of the end of the neck.

Keep us posted of the results. -Al

 

[PigButtons]

UPDATE:

I got a look at the rifle. Cutting right to the chase, I didn't fully diagnose it because when I looked at it the bolt handle was loose (braze giving way to getting smacked to open). However, I measured his fired cases at just in front of the belt and there was a .001 difference between one time and many time fired. Nothing hugely odd.

I checked the chamber. Small amount of carbon ring, and lotsa junk in the lug recesses. I also noted some peening on the bolt face edge from an over long action screw. That appeared old damage.

I tore down the bolt and cleaned it. I scrubbed the crap outta the chamber and lug recesses. I got most of the carbon ring out. I filed the action bolt enough to shorten it up. I also faced the little peen on the bolt- face with a stone. The rifle is soaking now overnight after some serious bore cleaning. Lots of brushing and some jusicious JB cleaned it up pretty well. It is still showing blue when I use Wipe out and I can see some carbon in the rifling. None of that speaks to the extraction issues though. I will return it to him clean. I also cleaned the trigger. Lots of rounds thru this old bird.

I am wondering if there was just enough guck in the lugs etc to stack tolerances.

I noted nothing out of the ordinary on the extractor or the cases.

It will go to Dave Bruno for a check up and bolt fix.

I had forgotten how nice the first gen Sendero rifles were.

I will report when we get a definitive answer. BTW, I did not chamber anything, loaded or not, due to bolt handle issue.

It would have to be a very close friend for me to do all that work for them. I would gladly teach them the techniques needed, but I get tired just cleaning my own guns. God bless you, (and I know that He does), for your kind, helpful spirit.

 

[PRR1957]

I had a 1996 made Remington Varmint Synthetic that the bolt handle cam started to gall where it cams against the receiver cam. I TIG welded a spot of 4140 to the galled spot on the bolt handle, ground it to shape and polished it. It worked smoothly after that.

 

[gunsandgunsmithing]

Buy...that's a new one on me. Normally, a 700 bolt handle is either on or off !

Hard to diagnose 'long distance' but if it's actually loose...you've found the extraction issue as you're loosing primary camming during extraction.

As mentioned earlier, I'd really get after the carbon build up. Those 7 Mags can really lay it down in there right ahead of the end of the neck.

Keep us posted of the results. -Al

I agree but will add, inspect the fired brass closely. Pits in the chamber will form on the case BUT they aren't nearly as indicative of how bad the pitting actually can be because with a big enough hammer, they smooth out a bit when the case begins to move rearward. My first guess is a neglected and pitted up chamber. Did the borescope show anything in the chamber than didn't look good?

 

[Mike Casselton]

Have you looked at the cocking cam?

If it gets grit or worse fine dirt on it it'll damn near prevent the bolt from opening.
If you remove the FP assembly and try it with out issue, then it's the cam.

It can also be verified by dry firing on an empty chamber and you'll still have the hard bolt lift.

Like this:
Close the bolt, dry fire, get hard lift.
Cycle the bolt, don't dry fire and cycle it. Easy lift? For sure it's the cocking cam.

 

[snert]

In regard to the loose bolt...It was REAL loose if you get my meaning.

But it was loose due to a 2x4 whacking it to get extraction...

Chamber was not buggered.

Throat was a mess.

I think it will be repaired and rebarreled. At least that is the plan.

I did not check cam...I am not that good of a mechanic. I am limited to basic stuff like cleaning and scrubbing. That's why we defaulted to Bruno when I saw the issues.

 

[kendog]

Had on come through a while back with similar issues. Rem 700 in 7 Rem Mag stainless. The guy didn't have to beat it open (yet), but it would get way stiff and sticky at the last of the opening lift. Turned out it was a combination of grit in the cocking cam along with grit and rust in the bolt body and trigger. Also had one of the snakey firing pin springs adding to the overall drag on the system. Cleaned and lubed the bolt inside and out, polished the inside of bolt body, polished chamber with diamond hone for good measure and problem went away. Just poor maintenance.

 

[Riesel]

Can someone please explain to me why so many shooters feel they have to get a bigger
stick/board/hammer to fix a problem, and then not just once, whack and repeat??
Just Curious
( Making it the subject of a thesis I'm working on. Seems to have something to do with men)
Thanks,
Riesel

 

[msalm]

All of the above may help, but the primary cause is the root of the bolt handle extraction cam. What was mentioned above about tig welding a small spot of additional steel on that front corner of the bolt handle will increase the extraction cam from maybe 10-20 thousandths to around 100 thousandths and your extraction issue will be solved. Or since the handle is loose already, have a replacement handle tig welded on with proper cam timing. Makes all the difference.