From time to time over the years Ive run into guns that have sticky bolts with very mild loads as well as very warm loads..

Im told this has to do with the bolt face, and its necessary to pull the barrel and resurface the locking lug area, the split lug on a Mauser is usually the culprit..

Ive never seen this mentioned on AR, but the one I had fixed worked like a charm..

This can be disturbing much less sending a wrong message to the reloader, when trying to load up max loads for a rifle..

Anybody got additional information on this would be appreciated in as much as its a common failure for lack of a better word.

I think I might have encountered this once on a 8x57 Mauser.

I tried some S&B factory ammo and it WAS real sticky. I was like "OH HELL" it was so hard to open. So this started my hand loading path for all my hunting cartridges.

I have a great hand load for that rifle now which is equal to the S&B is pressure and even ran some much hotter loads - never had an issue.

So in this case I attribute to poor brass? Not sure. It was odd.

Now, I've never had sticky loads with normal pressure, properly sized brass.

Take a loaded case and polish the brass. Insert in the chamber by hand and fire. Inspect for any hazing or grooves. If positive, you need to polish the chamber.

Take a section of an aluminum shotgun cleaning rod and hack saw a groove about 2 in long from the tip. Then cut a strip of alum/carbide paper 600 grit 2 1/4" wide. Insert one end into the groove and wrap it clockwise around the rod.

Adjust the length until it is a very snug grip in the chamber. You may have to insert a section of cleaning patch in the layers to help it fit.

Chuck the rod in a drill motor and spin in the chamber at medium speed for 30 seconds while moving the motor in and out.

Test fire and repeat as necessary.

If it is a Mauser and you are experiencing hard bolt lift with light loads it is most likely high pressure set back. If the action is a little on the soft side it will not shatter from a high pressure load it will set the lugs back. When that condition exists the receiver lugs will be normal at the beginning of lock up rotation then fall down into the low spot created by set back. I have observed this problem several times. That is why it is recommended to have Mausers reheat treated when rebarreling to a modern caliber.

This gun does this with any load mild or hot, the cases show no pressure signs at all..in fact its a bit sticky empty, but more so after firing a shot..Jack Belk says he can fix it by pulling the barrel and facing the lug slots or something like that..He is a great gunsmith btw.

Yes you can reface the receiver lugs and that will fix it for a short time. The case hardening will be thinner now and easier for the lugs to set back again only sooner. The proper repair would be reface the lugs then have the receiver reheat treated.

You said the bolt lift is stiff even with mild loads. That is a classic symptom of lug set back from a previous high pressure event.

Jack Belk was a charter member of the American Custom Gunmakers Guild . Very talented. He seemed to have dropped out of sight. What is he doing nowdays ?

I'm beginning to think brass quality variances are far outside what's "usual" / customarily expected.

One way to check lug set back is to remove the firing pin assembly insert bolt and close , hold gun vertical and use feeler gauges between rear bridge and bolt root . Gradually raise bolt and use feeler gauges to see if the gap gets smaller . With a light touch or feel you should be able to actually feel it in its set backed lug imprint and move the bolt nearer the front receiver ring as its raised from the closed locked position .
Hope this makes sense .

quote:

One way to check lug set back is to remove the firing pin assembly insert bolt and close , hold gun vertical and use feeler gauges between rear bridge and bolt root . Gradually raise bolt and use feeler gauges to see if the gap gets smaller . With a light touch or feel you should be able to actually feel it in its set backed lug imprint and move the bolt nearer the front receiver ring as its raised from the closed locked position .
Hope this makes sense .

Gary you are correct. After 45 years of gunsmithing I have seen this problem a number of times.

I concur that it’s most likely lug setback which is easy to see it you pull the barrel. I can usually feel the bolt pull forward a bit as it climbs the bump while gently opening the bolt that was closed on an empty chamber. When I have encountered it I have installed a new receiver as facing the lug seats and resetting the headspace will only be a temporary repair. I suppose you could have the receiver re-hardened to extend the life of the repair but I’ve only had a couple of rifles in here with this problem and replacing the receiver was cost effective.

What Im wondering is does this even need to be repaired, as a first firing would fireform to the chamber and proper reloading would correct the problem. Ive been shooting it as is..I see on other signs of pressure, but these are max loads...????????????

The rifle is a very nice Brno mod. 21 rifle with a mint bore..I also was wondering if the V in the cocking piece was softened when the bolt handle was lowered for scope clearance..If so that would simply require rehardening.

More likely than lug setback, which would be very rare on any CZ product; is one of two things that are usually overlooked.
1. Softened cocking cam. The cam is steep and must be hard to work smoothly.
2. Internal firing pin safety interlock interference. Most people do not even know that exists, but it is a feature of all 98 pattern Mausers.

DPcd,
Im thinking its a soft cocking cam as the bolt was butter knife bolt handle modified for low scope mounting and to remain looking original...That and the primers are Ok but flat, not cratering, no smudges around them no marks on the case heads except on occasion they mark on the openning, primers reloaded snug as new and slick thru the resizer, almost no expansion of cases...add to that that Im flying by the seat of my pants on pressure with the 8x60 that I decided to increase 8x57 loads 5%, and it appears perhaps a tad heavy, maybe as it shows a apparent amount of recoil over the 8x57...Just some ideas that go along with your post...I should probably rechamber both my 8x57 and 8x60 to the 8mm-06 or 06 Imp..

Another issue I have encountered with Mausers is the extraction cam on the bolt root not making contact with the rear bridge cam. This is described as being the primary extraction mechanism.

quote:

Originally posted by dpcd:
More likely than lug setback, which would be very rare on any CZ product; is one of two things that are usually overlooked.
1. Softened cocking cam. The cam is steep and must be hard to work smoothly.
2. Internal firing pin safety interlock interference. Most people do not even know that exists, but it is a feature of all 98 pattern Mausers.

That is very true; that makes you have to actually pull the brass out without any mechanical advantage. I have one here like that now; just a tolerance stack up, or when they welded the bolt handle on, they ground off more than needed on the top front of the shank. Solution is to weld more on there.
Good call.

When we were Savage repair center in the early 1980's we had a 110C in 243 come in.

No mater what ammo that was shot in it you had to use a soft mallet to pound the bolt handle up to open the action after firing.

This was only after firing the cartidge, the action would close and open just fine with ammo in the chamber the problem was not until you shot the cartidge.

Took us about a week to figure it out.

The parts had to be made on a Friday afternoon, and then assembled on a Monday morning.

Nothing about the receiver, bolt, or barrel was straight, centered or concentric.

So what we figured out was the chamber was offset, and oversize, when the cartidge was fired it then was tightly held in the chamber and the offset rim would then drag on the inside diameter of the bolt face recess.

The cure, to set the bolt head up in the lathe and open the rim recess diameter .008"

Worked like a charm after that.

JW

Thinking back and trying to absorb all this good information it dawned on me that I never had this problem until the bolt was lowered, at least not that I recall and Im sure I would have noticed it..then I noticed that the other Brno mod 21 and 22s have a not sticky but slightly heavy lift on the bolt, loaded or not, tried some others locally and it seems that most if not all are..Im going to harden that cam first of all and go from there.

JW; that is brilliant; and a scenario I never even thought about. Bolt nose rim rubbing on a cartridge rim...very interesting.....

I have a custom FN actioned 270 that does the same thing. Each cartridge case after firing has a slightly burnished spot on the cartridge case. The cure is as been discussed but the rifle is a real tack driver and I don't want to mess with it .

Mark

Yes I have a 1916 Spanish Mauser that had the bolt nose interference problem. Normally on a Mauser that extension below the ejector slot has a eased portion next to the case rim. On mine it was sharp and pointed. When a case was fired bolt lift was hard and brass was shaved off the rim. Ground it back to match another specimen and now works perfect.

like Jim I have found radically excentric bolt face issues at times compounded by excentrically cut receiver threads at the same time, then toss in a misaligned firing pin hole and you got a birds nest

The last 4 Small Ring Dovetailed Brno actions I worked on were all soft in my opinion. One Rockwell tested at 27 "C" the others much lower. These were made in 1950 and 1951. Blanchard got all 4. Nipped that in the bud early so we wont have the ejector ridge appear on the upper lug seat later on.

I have an arisaka in 257 Roberts that acted the same way.
probably why I got it so cheap [plus it is double butt ugly] but it is stupid accurate so I investigated a bit further.

the extractor was binding up against the bolt face and jamming against the side of the case, and that was causing my sticky hard to open bolt issues.
once that got carefully filed down it now operates with all the smoothness an arisaka can operate with.

quote:

Originally posted by dpcd:
More likely than lug setback, which would be very rare on any CZ product; is one of two things that are usually overlooked.
1. Softened cocking cam. The cam is steep and must be hard to work smoothly.
2. Internal firing pin safety interlock interference. Most people do not even know that exists, but it is a feature of all 98
pattern Mausers.

Not on all 98 Mausers , Mexican 98s don't have it neither do some Parker hale 98s .
I recently had a Brno 7mm Mauser that was absolutely beautiful , but had lug set back , bad . It was a large thread small ring std length in a MANNLICHER stock , double set triggers and a beautiful 1950s commercial rifle . Receiver was soft . A friend insisted on mounting a scope , after many unsuccessful attempts of changing his mind I finally drilled . I was afraid as usually they are hard , this was too soft . After I'm done he tells me of his hard bolt lift , great , so now with my drilling info and a bore scope I could clearly see the lug imprint then stripped the bolt and confirmed its movement on opening .
Ashame , I think these commercial guns were large rings that they ground down and never heat treated properly . I found some adds of these rifles for sale in the early 50s from Kleins I think .

quote:

Originally posted by Atkinson:
From time to time over the years Ive run into guns that have sticky bolts with very mild loads as well as very warm loads..

Im told this has to do with the bolt face, and its necessary to pull the barrel and resurface the locking lug area, the split lug on a Mauser is usually the culprit..

Ive never seen this mentioned on AR, but the one I had fixed worked like a charm..

This can be disturbing much less sending a wrong message to the reloader, when trying to load up max loads for a rifle..

Anybody got additional information on this would be appreciated in as much as its a common failure for lack of a better word.

Would this be a commercial small ring ?

Gary,
Yes the Brno mods 21 and 22 are commercial version of the G33-40 small ring Mauser, came in double square bridge or round top..Probably the finest factory rifle ever..Original guns actually used the German Customs Service mod. 35? as I recall, its also a G33-40 for all purposes but sans the rail slot..

Also early on they came in the very rare LR Mauser round top..other than that they are clones of each other..I have one LR and several small ring...Came in 8x57, 6.5x57, 8x57, 7x64, and 7x57..Fantastic rifles, the 21 is a rifle and the 22 is a full stock manlicher type that came in 20 and 24 inch,as did a few rifles btw, well in European measurement, that's close enough...The LR came with a round barrel, full rib with integral sights and strangly enough will fit the 21 or 22 stocks. Ive made a couple of switch barrels using only original factory barrels, and they all went together in the factory inletting, amazing.. they have the same demensions down to the wire..Interesting history behind these guns, and that history is a bitch to pull up.I still run down every thing I can on them, most of which is from collectors and Europeans note books and some German records, and its hard to separate fact from fiction, but do the best I can. Its worth it on such a Quality plus rifle..Alf, who posts here is a good source of information on these fine guns, and has some nice ones in his collection. I got most of mine when they were in the $300 price range now $1500 is a fair deal..