I've got an old Mossberg Model 800A Bolt action in 308 Win. I got the thing dirt cheap many years ago and when I first got it about a third of the time the bolt lift would be hard to VERY hard on the thing after firing a round. I set the thing aside for several years and after read some decided to re-evaluate the situation. I fired a few more cases and carefully inspected them, noticing what looked to be too much of a bulge where you typically see the pressure ring in front of the case head. I took it into a local shop where I trusted the proprietor. He looked the thing over and told me that it had excessive headspace and that was what was causing the buldge and the heavy bolt lift/sticky extraction. With my permission he sent it out to his preferred smith who supposed set the barrel back a thread and recut the chamber on it. This was about 4 years ago. At the time I kept thinking I NEED to get this thing out and test fire it and make sure all is well and right with the world. Well long story short, it didn't happen. Fast forward to about three weeks ago. I was out at my grandmothers farm and was going to give it a run through and try to sight it in with some Win. factory loads. Only got a chance to squeeze off 7 rounds. Everything seemed O.K. no buldges just the normal pressure rings, granted the thing feeds rounds out of the magazine like crap, but the 2 groups I fired looked decent under 2" at 100 yds. Move ahead to last weekend I take the thing out to get serious about working the bugs out of the thing, see what it REALLY CAN do see if there is anything that I can do about the feeding. I was considering taking the thing out for deer this fall. Well I started using a different box/lot of the same Winchester 180grn. Power Point loads and shot a group of 3 which was nothing to write home about, but not bad. I decide to fire another group and on the second shot of the second group of three the case extracted a little heavy and I'm instantly thinking NOT GOOD felt almost EXACTLY like I remember things being before. I fire the third shot and go to extract and eject the empty case from the chamber and bolt lift is SLIGHTLY heavy, BUT WORSE IS THAT I can't seem to get the bolt to pull open!!! I tried using pretty stout hand force and it just seems to be all locked up in a BIG WAY!

Here's what's odd. Last weekend the thing seemed to be feeding considerablely better. After the bolt stuck I started going through my fired cases from the day. I started with the second to last shot and noticed what seems to be a LARGER bulge in front of the case head than I had before having it worked on. I then stepped it back and it seems like each shot got a bigger and bigger bulge in it on Sat. until the thing locked up. Upon inspection I also noticed that most of the cases seem to be bulged on one side considerablely more than the other, some to the point where one side doesn't look like it has expanded at all with an almost scary bulge on the other. I find this strange since the cases from a couple weeks earlier this doesn't visually appear to be the case.

My question is does anyone here have any ideas on what is going on here?????

Next question is what should I do from here? Should I try to get the empty out of the rifle? Take it to the smith? Chop it up for scrap? Has anyone ever heard of something like this happening to a Mossberg 800?

Thankfully it was the last round in the gun, so there are none trapped under in the mag.

All thought are appreciated.

Thanks in advance.

Tom

sounds to me like you might have an egg shaped chamber. Did this mystery Smith run the reamer in by hand and not get square pressure on the reamer resulting in an egg shaped chamber? You might check you case length and see if it isn't maybe pinching the neck around the bullet and crimping it tight, thus causing extreme chamber pressures. It could have a short neck from a reground reamer. It could also be that the one thread that the mystery Smith wasn't enough to clean up the chamber. How about action itself, is it dry and causing metal to be galled from the bolt and mating parts?

A picture of the brass here would be worth a thousand words, from what you describe to me it sounds like the bolt is setting back into the lugs? Is this bulge all the way around the brass, like a small donut?

Now what to do from here, that depends!

The smith doesn't know if you've only shot this thing 10 times or you've run a couple cases of over pressure phillipine surplus machine gun ammo through it, so hopefully you have some relationship with the smith. 1 round or 1000, 4 years is a long time to warranty.

I think I'd suggest bringing it to the smith with the empty still in it, he might be able to notice a clue when getting it out as to what the actual problem is.

I have one in 243 which has way to much headspace too. I haven't shot it much because of the headspace and because only accurate rifles are interesting! I haven't measured the fired case diameters but they do seem to expand a lot.

I would be suspicious of the chamber too. The barrel shank diameter is .875" on the Mossberg and it is possible the shank has swelled from a past overload.

Several good point already made. Thanks!

Yes, when I first noticed the off center bulging on Sat. Egg shaped chamber came to mind. I seems odd though that the first set of shots didn't seem to have the problem, but I haven't gone back yet to CLOSELY double check that nor have I gotten around to taking any measurements. Work has me back in the same situation that caused me to put it on the back burner in the first place.

As for pictures I'm still in the dark ages as far as posting pics. on the internet or I'd love to put some up to help.

And YES Mark you are MOST CORRECT 4 years is a VERY long time. Much more than I ever wanted to slip away. As far as a warranty I don't know if I can even track down said mystery smith let alone make him make it right. The shop owner is now on the other side of the state having followed his wife's much more lucrative medical career and I know the smith he was using is somewhere half way between us. I'm thinking I will have to find a 3rd actually I guess it would be a 4th party to clean up this mess if I decide to play further. I'm just not sure who I'd go to or should trust with it.

As far as how the chamber was recut I admit to being too ignorant to have asked those kinds of questions and like I said don't know if I could find out at this point so I'm afraid I'm of no help on that point.

I was wondering about lug set back myself, especially since the problem seemed to grow back.

The barrel shank diameter is something that I hadn't given any thought to, not knowing my situation.

I agree only accurate guns are interesting,, to shoot. I really find some of the design feature on this rifle interesting and I'm still kind of hoping to get it to a point where it's interesting to shoot to boot. Looks like I've got some thinking and soul searching to do.

Keep the thoughts coming. Thanks!

Tom

I dug mine out of the safe to take a look at it. It is out of the stock right now. I see a couple things that could be the problem.

One is that the nose of the bolt is rubbing on the back of the barrel in one spot. The extractor also protrudes beyond the bolt nose. The extractor is spring loaded so contact with the back of the barrel pushes it back into the bolt. If there is a burr or some other irregularity on the back of the barrel it could hang the extractor up and make it hard to turn the bolt.

The other thing is that these have about a 60 degree bolt lift so the angle on the cocking cam in the bolt is fairly steep. Mine cocks fairly hard even when it is empty. You might try taking it out of the stock and removing the trigger and try getting some lube on the cocking cam in the bolt. There is one screw and one pin holding the trigger housing to the action. There aren't any loose parts to fly out when you take it off so don't worry about that. There is a long slot through the bottom of the receiver where the trigger fits so you might be able to see if it is the cocking cam hanging up. With it out of the stock and looking up through the magazine you might be able to see if one of the six locking lugs is hanging somewhere too.

I also measured some fired cases from mine. The maximum diameter is a hair over .471" and nice and round so that isn't to bad. The base to shoulder is about 1.575" which is a little over the 1.560" measurement the loading manuals show.

I agree they are an interesting action and that is why I still have it. The barrel is pitted on mine so I am going to rebarrel it and play with it some more. Since it has the small shank just about any takeoff barrel can be rethreaded to fit. The trigger needs work and I don't know who that stock fits-he probably isn't human, but I don't see any reason it won't shoot.

Another thought is that maybe the scope base screws are to long and binding the bolt. Both front base screws go into locking lug recesses.

quote:

Originally posted by Marc:
I dug mine out of the safe to take a look at it. It is out of the stock right now. I see a couple things that could be the problem.

One is that the nose of the bolt is rubbing on the back of the barrel in one spot. The extractor also protrudes beyond the bolt nose. The extractor is spring loaded so contact with the back of the barrel pushes it back into the bolt. If there is a burr or some other irregularity on the back of the barrel it could hang the extractor up and make it hard to turn the bolt.

The other thing is that these have about a 60 degree bolt lift so the angle on the cocking cam in the bolt is fairly steep. Mine cocks fairly hard even when it is empty. You might try taking it out of the stock and removing the trigger and try getting some lube on the cocking cam in the bolt. There is one screw and one pin holding the trigger housing to the action. There aren't any loose parts to fly out when you take it off so don't worry about that. There is a long slot through the bottom of the receiver where the trigger fits so you might be able to see if it is the cocking cam hanging up. With it out of the stock and looking up through the magazine you might be able to see if one of the six locking lugs is hanging somewhere too.

I also measured some fired cases from mine. The maximum diameter is a hair over .471" and nice and round so that isn't to bad. The base to shoulder is about 1.575" which is a little over the 1.560" measurement the loading manuals show.

I agree they are an interesting action and that is why I still have it. The barrel is pitted on mine so I am going to rebarrel it and play with it some more. Since it has the small shank just about any takeoff barrel can be rethreaded to fit. The trigger needs work and I don't know who that stock fits-he probably isn't human, but I don't see any reason it won't shoot.

Another thought is that maybe the scope base screws are to long and binding the bolt. Both front base screws go into locking lug recesses.

If the action had setback then it would have manifested itself right from the get go after the mystery Smith. But it went away and then came back after the barrel was heated up. The bulge on just one side of the spent case tells me that the chamber is not round but egg shaped. If the scope base screws were protruding into the bolt recess it would show all the time. I'm of the impression that the cases are in dire need of trimming and are being crimped into the chamber tight enough that they don't want to let go causing dangerous chamber pressures. This could be the reason for the bulging. How many times have the cases been fired? I thought there were some new factory rounds also fired. At this point I would point a finger at extreme chamber pressures. As for the bolt binding in the action, it would bind all the time if there was interference. I suspicion that the cases are too long. Just my two pennys.

In today's era of undersized brass you can have a concntric chamber of mimimum dimensions and still have brass exhibit a bulge on one side.

Definitely check brass length if using reloads. Otherwise, a chamber cast is probably in order as is inspection by a competent gunsmith.

quote:

Originally posted by tdobesh:
<SNIP>

And YES Mark you are MOST CORRECT 4 years is a VERY long time. Much more than I ever wanted to slip away. As far as a warranty I don't know if I can even track down said mystery smith let alone make him make it right. The shop owner is now on the other side of the state having followed his wife's much more lucrative medical career and I know the smith he was using is somewhere half way between us. I'm thinking I will have to find a 3rd actually I guess it would be a 4th party to clean up this mess if I decide to play further. I'm just not sure who I'd go to or should trust with it.


Tom

Hey don't feel bad! I bought a Marlin 57 lever action 22 Magnum that had been rebarreled and shot it a couple times and put away for about a year, Next time I took it out the first 3 rounds loosened the barrel up to where it would wobble! Since then if a gun is a shooter I made it mandatory to shoot a box of shells through it in the next day or two after I buy it.

PS, while I'm on the subject if anyone has a Marlin 57 or 57M barrel send me a PM.

olcrip,

It was all winchester power point factory loads. 180grn From two different boxes from two different lots. If the cases are too long I'd be a little surprised, but not shocked. Obviously all first firing, AT LEAST I SHOULD HOPE!

If its case neck tension from running the neck into the lands, I would suggest it's likely the new chamber was cut too short.

quote:

Originally posted by tdobesh:
olcrip,

It was all winchester power point factory loads. 180grn From two different boxes from two different lots. If the cases are too long I'd be a little surprised, but not shocked. Obviously all first firing, AT LEAST I SHOULD HOPE!

If its case neck tension from running the neck into the lands, I would suggest it's likely the new chamber was cut too short.

If the chamber is short cut the cases should show a slight ring around the mouth almost like a military tye crimp. If there are no signs of a tight shamber induced crimp then it's time for a cerrosafe chamber cast. Have you actually measured the empties from that chamber? Does the bolt close snug or with effort when you put it into battery?