Mauser Sticky Bolt

JFS0650 · December 14, 2012, 05:24 PM

Hi guys,

I have a Gustav 1920 Mauser that I fired for the first few times ever this afternoon. The last few rounds, the bolt became a little difficult to open...nothing that I really had to slam a hand on though. I've come across a few threads on this but I don't really understand the causes of this.

Any chance I just had some grit down in the bolt? Now that I'm home and I cleaned the outside of the bolt, etc, it's moving slicker than duck poo.

Most importantly, should I be worried about the safety of this rifle? I'll trash it before risking my face.

Thanks--

**4V50 Gary** · December 14, 2012, 05:25 PM

Examine the spent cartridges. Any flattening of the case head? Flattened primers? Cracked or ballooned case?

JFS0650 · December 14, 2012, 05:39 PM

Arghhh! I didn't bring any back. Crap. If so what would that tell me?

JFS0650 · December 14, 2012, 05:47 PM

Ok, I see on a site that the flattened primer indicates the load is too hot. These were factory (but old) Norma rounds. Any details on why this makes the bolt hard to open and the degree of safety concern? Thanks!

Dfariswheel · December 14, 2012, 06:43 PM

Causes could be the rifle has developed excess head space. This allows the cartridge to expand more and can cause hard extraction.
To detect this, have a gunsmith check the head space with a set of precision head space gauges.

The chamber may be fouled and/or rusty, pitted, or bulged. This will cause the case to stick and causes hard bolt operation.
Scrub the chamber with a chamber brush and inspect for any of the above.

A dirty bolt could be the problem. A full disassembly and cleaning, followed by a light coat of grease on the internal parts may fix it.

Always put a dab of grease on the cocking cam on the lower rear of the bolt body.
That's the slanted cam at the rear that cocks the rifle when the bolt is opened.
A little grease there is often all that's needed to smooth bolt operation.

A worn bolt cocking piece and trigger sear can cause hard operation.

Last, try a different brand of ammo.

**4V50 Gary** · December 14, 2012, 06:48 PM

Listen to Dfariswheel. He's a retired gunsmith.

If your gun has developed excessive headspace, it needs a trip to the gunsmith. Generally the barrel must be removed from the receiver. The receiver is then measured (distance from front of receive ring to bolt face) and distance from the receiver C-ring to the front of the receiver. You barrel shank may have to be turned down a bit to shorten the headspace.

Get the expended cases and examine them. Also inspect the fresh ones before you shoot them. Measure them for length and compare them to military specs.

JFS0650 · December 14, 2012, 08:03 PM

Great info; thanks to all. I may go back to the range tomorrow to put 5 rounds through just to get the cartridges and then go to the 'smith.

HiBC · December 15, 2012, 04:09 AM

All good info.I have one question.Did you put the rounds down in the magazine so they could feed up,or did you single load and just close the bolt on one round?

The way that rifle works you need to put them down in the mag box.

**4V50 Gary** · December 15, 2012, 11:36 AM

The gun was designed to be fed from the magazine. That is to say, you push five rounds down into the internal magazine.

However, since you're testing it, single shot it. You don't have to fire five either. Fire only one and examine the case. If there's any flattening of the case head or the primer, ballooning or cracking of the case, don't shoot it anymore. It's has excessive headspace and the barrel shank must be reduced (cutting down the shank reduces the length of the chamber and eliminates the headspace issue).

JFS0650 · December 15, 2012, 06:38 PM

Yes, it was only magazine fed. I dropped it off at the gunsmith today. I'll have it back in a week with the results of the headspace check...Will update.

James K · December 15, 2012, 07:59 PM

Another possible cause would be a battered lug seat, if the rifle was fired a lot or with heavy loads. The result is that the bolt lugs peen the lug seats and create dented spots. When the bolt is turned, the lugs have to be moved out of that "hole". Plus, the excess headspace allowed the case to back out slightly and so it is holding the bolt back, making it even harder to turn. Obviously, this suggestion is sight unseen, but if that is the problem, the action needs a really competent gunsmith to correct it, if it can be corrected at all.

Jim

December 14, 2012, 05:24 PM	#1
JFS0650 Junior Member Join Date: September 7, 2012 Posts: 10	Mauser Sticky Bolt Hi guys, I have a Gustav 1920 Mauser that I fired for the first few times ever this afternoon. The last few rounds, the bolt became a little difficult to open...nothing that I really had to slam a hand on though. I've come across a few threads on this but I don't really understand the causes of this. Any chance I just had some grit down in the bolt? Now that I'm home and I cleaned the outside of the bolt, etc, it's moving slicker than duck poo. Most importantly, should I be worried about the safety of this rifle? I'll trash it before risking my face. Thanks--

December 14, 2012, 05:25 PM	#2
4V50 Gary Staff Join Date: November 2, 1998 Location: Colorado Posts: 21,831	Examine the spent cartridges. Any flattening of the case head? Flattened primers? Cracked or ballooned case? __________________ Vigilantibus et non dormientibus jura subveniunt. *Molon Labe!*

December 14, 2012, 06:48 PM	#6
4V50 Gary Staff Join Date: November 2, 1998 Location: Colorado Posts: 21,831	Listen to Dfariswheel. He's a retired gunsmith. If your gun has developed excessive headspace, it needs a trip to the gunsmith. Generally the barrel must be removed from the receiver. The receiver is then measured (distance from front of receive ring to bolt face) and distance from the receiver C-ring to the front of the receiver. You barrel shank may have to be turned down a bit to shorten the headspace. Get the expended cases and examine them. Also inspect the fresh ones before you shoot them. Measure them for length and compare them to military specs. __________________ Vigilantibus et non dormientibus jura subveniunt. *Molon Labe!*

December 15, 2012, 11:36 AM	#9
4V50 Gary Staff Join Date: November 2, 1998 Location: Colorado Posts: 21,831	The gun was designed to be fed from the magazine. That is to say, you push five rounds down into the internal magazine. However, since you're testing it, single shot it. You don't have to fire five either. Fire only one and examine the case. If there's any flattening of the case head or the primer, ballooning or cracking of the case, don't shoot it anymore. It's has excessive headspace and the barrel shank must be reduced (cutting down the shank reduces the length of the chamber and eliminates the headspace issue). __________________ Vigilantibus et non dormientibus jura subveniunt. *Molon Labe!*

December 14, 2012, 05:39 PM	#3
JFS0650 Junior Member Join Date: September 7, 2012 Posts: 10	Arghhh! I didn't bring any back. Crap. If so what would that tell me?

December 14, 2012, 05:47 PM	#4
JFS0650 Junior Member Join Date: September 7, 2012 Posts: 10	Ok, I see on a site that the flattened primer indicates the load is too hot. These were factory (but old) Norma rounds. Any details on why this makes the bolt hard to open and the degree of safety concern? Thanks!

December 14, 2012, 06:43 PM	#5
Dfariswheel Senior Member Join Date: May 4, 2001 Posts: 7,478	Causes could be the rifle has developed excess head space. This allows the cartridge to expand more and can cause hard extraction. To detect this, have a gunsmith check the head space with a set of precision head space gauges. The chamber may be fouled and/or rusty, pitted, or bulged. This will cause the case to stick and causes hard bolt operation. Scrub the chamber with a chamber brush and inspect for any of the above. A dirty bolt could be the problem. A full disassembly and cleaning, followed by a light coat of grease on the internal parts may fix it. Always put a dab of grease on the cocking cam on the lower rear of the bolt body. That's the slanted cam at the rear that cocks the rifle when the bolt is opened. A little grease there is often all that's needed to smooth bolt operation. A worn bolt cocking piece and trigger sear can cause hard operation. Last, try a different brand of ammo.

December 14, 2012, 08:03 PM	#7
JFS0650 Junior Member Join Date: September 7, 2012 Posts: 10	Great info; thanks to all. I may go back to the range tomorrow to put 5 rounds through just to get the cartridges and then go to the 'smith.

December 15, 2012, 04:09 AM	#8
HiBC Senior Member Join Date: November 13, 2006 Posts: 8,283	All good info.I have one question.Did you put the rounds down in the magazine so they could feed up,or did you single load and just close the bolt on one round? The way that rifle works you need to put them down in the mag box.

December 15, 2012, 06:38 PM	#10
JFS0650 Junior Member Join Date: September 7, 2012 Posts: 10	Yes, it was only magazine fed. I dropped it off at the gunsmith today. I'll have it back in a week with the results of the headspace check...Will update.

December 15, 2012, 07:59 PM	#11
James K Member In Memoriam Join Date: March 17, 1999 Posts: 24,383	Another possible cause would be a battered lug seat, if the rifle was fired a lot or with heavy loads. The result is that the bolt lugs peen the lug seats and create dented spots. When the bolt is turned, the lugs have to be moved out of that "hole". Plus, the excess headspace allowed the case to back out slightly and so it is holding the bolt back, making it even harder to turn. Obviously, this suggestion is sight unseen, but if that is the problem, the action needs a really competent gunsmith to correct it, if it can be corrected at all. Jim