CZ 550 Lott feeding issue?

I took my recently acquired CZ 550 rechambered from WM to the Lott cartridge to the range today. When cycling cartridges through the action from the magazine, sometimes the Lott cartridge rims aren’t captured fully into the bolt face before the cartridge enters the chamber. The cartridge then hangs up on the side of the chamber before entering it? Doesn’t seem to happen when loading WM cartridges? Stiffer magazine follower spring needed? Thanks!

COElkHunter -

Things I could think of:

- Length of cartridge/catching the projectile - the feeding geometry is off (which probably leads to the next possibility)
- Feed rails now need work - if the bolt face is not capturing the head of the cartridge, that tells me it is not coming up out of the magazine correctly. Stronger follower spring is what I would try first - I was taught that one should not play with feed rails in a cavalier manner.

I bet the reason the projectile is hitting the side of the chamber is because it is not being captured on the bolt face, which would hold it straight for loading into the chamber. Try the spring first - least possible damage to rifle if it isn't needed. Does it do this on the last round, or the next to last (ones fed from the right or left of the magazine)? Have you played with COAL/verified it is proper? Is it the first round out the magazine (when it is lifting the most weight), or is it the last cartridge?

I fear it will be the feed rails though.

Hope this helps. Perhaps someone with better expertise will diagnose things for you?

USMA84DAB said:

COElkHunter -

Things I could think of:

- Length of cartridge/catching the projectile - the feeding geometry is off (which probably leads to the next possibility)
- Feed rails now need work - if the bolt face is not capturing the head of the cartridge, that tells me it is not coming up out of the magazine correctly. Stronger follower spring is what I would try first - I was taught that one should not play with feed rails in a cavalier manner.

I bet the reason the projectile is hitting the side of the chamber is because it is not being captured on the bolt face, which would hold it straight for loading into the chamber. Try the spring first - least possible damage to rifle if it isn't needed. Does it do this on the last round, or the next to last (ones fed from the right or left of the magazine)? Have you played with COAL/verified it is proper? Is it the first round out the magazine (when it is lifting the most weight), or is it the last cartridge?

I fear it will be the feed rails though.

Hope this helps. Perhaps someone with better expertise will diagnose things for you?

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Thanks for your reply. The WM cartridges feed smoothly, so I’m thinking with the longer Lott cartridge, a stiffer magazine spring might be needed to jam (assist) the cartridge rim into the bolt face quicker before the cartridge attempts to enter the chamber? Don’t know for sure? These are factory Nosler 500gr. Partitions so I don’t think the COAL is an issue? So, I just ran two cycles of ten Lott cartridges through it with no feeding issues? What’s up with that? Maybe it hasn’t been shot much?

Taking your last note into consideration......you may be causing the malfunction by not being forcefull in your recycling. Slow or hesitation in cycling can cause pickup problems ,particularly in new rifles

Luvthunt said:

Taking your last note into consideration......you may be causing the malfunction by not being forcefull in your recycling. Slow or hesitation in cycling can cause pickup problems ,particularly in new rifles

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That could very well be? The last two five round cycles I tried after the OPs post were fast and smooth. This rifle was bought used, but it doesn’t appear it has been shot much? The rails have very little visual wear to them. That also brings up another point. Who would have a rifle rechambered and then not shoot it much or at all with the new chambering?

Maybe someone who failed to recognize the added recoil altho as in many things the reasons for selling are endless.
Will add my Lott started to have feed problems after several years of usage and as suggested above the follower spring was replaced and the problem disappeared.

CoElkHunter said:

When cycling cartridges through the action from the magazine, sometimes the Lott cartridge rims aren’t captured fully into the bolt face before the cartridge enters the chamber. The cartridge then hangs up on the side of the chamber before entering it?

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1) Based on looking at rifle/pistol feeding of crf guns in the past, I’m thinking this is the cartridge getting loose as the bolt comes back. Likely this is a follower spring issue. The 458 Lott is hard on these parts. It just weighs a lot so it needs more spring force. The feed rails could be making that worse.

2) This is typically a crimp/ extractor adjustment issue. First, these rounds need good crimp to feed or the case hangs on the belt part of the chamber. Second, IMO the extractor doesn’t need to push that far over. It should be adjusted to allow the cartridge attitude to be more straight.

CoElkHunter said:

Who would have a rifle rechambered and then not shoot it much or at all with the new chambering?

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All kinds of folks. 458’s are cool & romantic until you shoot them....especially the Lott. I like the recoil, but it also tends to kick and slap like an ex-wife tied to an old mule! It’s an acquired taste for sure.

nksmfamjp said:

1) Based on looking at rifle/pistol feeding of crf guns in the past, I’m thinking this is the cartridge getting loose as the bolt comes back. Likely this is a follower spring issue. The 458 Lott is hard on these parts. It just weighs a lot so it needs more spring force. The feed rails could be making that worse.

2) This is typically a crimp/ extractor adjustment issue. First, these rounds need good crimp to feed or the case hangs on the belt part of the chamber. Second, IMO the extractor doesn’t need to push that far over. It should be adjusted to allow the cartridge attitude to be more straight.



All kinds of folks. 458’s are cool & romantic until you shoot them....especially the Lott. I like the recoil, but it also tends to kick and slap like an ex-wife tied to an old mule! It’s an acquired taste for sure.

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After two Ops stated their CZ Lotts have both Lott and WM stamped on the barrels like mine (maybe older CZs?), I’m convinced it’s a factory chambered Lott. The last few times I cycled rounds they didn’t hang up, but a stronger magazine spring would be better. The Lott does “slap” (actually more of a hard push) a bit, but for me it’s not unmanageable? And, off this thread a bit, but this CZ Lott has no receiver crossbolts. The stock seems tight to the receiver/frame. But I don’t see how the stock could crack as the recoil isn’t that atrocious? I give with the recoil, so unless you have the rifle in something like a lead sled which doesn’t move, I just can’t see the stock cracking? Maybe I’m just naive?

Just screw in a .375 barrel, those shells might feed better.

So I worked on my CZ quite a bit to get it feeding properly. Not an expert but a fair amount of analyses of the action. I actually changed mine to Lott recently because the Win Mag works through tighter angles to get into the chamber so I think the Lott is more reliable feeding wise. The camming action that you talk about is normal. By the time the front of the bullet is in the chamber, the magazine springs job is all but done. The round cams up off the feed ramp and chamber mouth and slides up the bolt face. If it hangs up there, it is likely to be three possibilities. The bolt face is not smooth, the claw extractor is not smooth or the little rim around the top of the bolt face is not smooth. These three surfaces will work if you run the bolt vigorously but I was amazed at how much easier that little part of feeding smoothed up when I polished these surfaces. The bullet actually forces itself under the extractor and you can polish off the corner to make it slip under more easily. But it is a fine line, that tension is what makes it a controlled feed, to much space and the cartridge is not held, too much tension and rough edges and you have rough and hard feeding. I marked the contact points on this pic of my CZ 550 bolt. Also check the bolt face is smooth. If there is a bump or rough surface on those key points, it will make that lttle bit of the load cycle feel harder. With the different angles of the Lott, it may even hang up as the rim slips under the claw. I took the claw off and polished those 3 surfaces with 600 grit paper. I was amazed how much easier it made the loading. Or just shoot 500 rounds and it will wear smooth.

Nhoro said:

So I worked on my CZ quite a bit to get it feeding properly. Not an expert but a fair amount of analyses of the action. I actually changed mine to Lott recently because the Win Mag works through tighter angles to get into the chamber so I think the Lott is more reliable feeding wise. The camming action that you talk about is normal. By the time the front of the bullet is in the chamber, the magazine springs job is all but done. The round cams up off the feed ramp and chamber mouth and slides up the bolt face. If it hangs up there, it is likely to be three possibilities. The bolt face is not smooth, the claw extractor is not smooth or the little rim around the top of the bolt face is not smooth. These three surfaces will work if you run the bolt vigorously but I was amazed at how much easier that little part of feeding smoothed up when I polished these surfaces. The bullet actually forces itself under the extractor and you can polish off the corner to make it slip under more easily. But it is a fine line, that tension is what makes it a controlled feed, to much space and the cartridge is not held, too much tension and rough edges and you have rough and hard feeding. I marked the contact points on this pic of my CZ 550 bolt. Also check the bolt face is smooth. If there is a bump or rough surface on those key points, it will make that lttle bit of the load cycle feel harder. With the different angles of the Lott, it may even hang up as the rim slips under the claw. I took the claw off and polished those 3 surfaces with 600 grit paper. I was amazed how much easier it made the loading. Or just shoot 500 rounds and it will wear smooth.

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Great points about the polishing of those surfaces. What is interesting with this rifle’s feeding issue with the Lott cartridges, is that WMs feed smoothly through it? It seems with the shorter WM there is an instant more of time for the rim to be captured into the bolt face before the cartridge attempts to enter the chamber? That’s why I questioned whether the magazine spring should be stiffer? Although, I wouldn’t know where to find one? Are they rifle brand, model specific? Or maybe Mauser action specific? I’m going to continue to work the action with the cartridges from the magazine for awhile and see what happens. If the feeding issue persists, I’ll have a gunsmith I know check it out? Thanks!

You smoothed the BACK side of the extractor, right? Doesn't the dish shape on the front of the extractor control the angle the shell is thrown out when ejected?

CBH Australia said:

Just screw in a .375 barrel, those shells might feed better.

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Actually, I might keep my eye out for a .416 barreled action cause I’m about to run a Lott case through my .416 Taylor die and have a .416 Lott or something? Maybe a .416 Remington or .416 Hoffman barrel would work? Maybe I should forget the entire idea and eventually just buy a .416 Barrett! Ha! Ha! Ha!

postoak said:

You smoothed the BACK side of the extractor, right? Doesn't the dish shape on the front of the extractor control the angle the shell is thrown out when ejected?

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There is a tutorial on line that I followed. If you take a case and slide it into place up the face of the bolt, you will see the contact points,basically the three points that I highlighted with an arrow on my pic. The main part on the extractor that needed smoothing was actually the bottom edge and mostly that bottom corner. It rides in the slot of the rim. I must stress that this effects how tightly the cartridge is held so remove material at you own peril. I used 600 grit paper and simply polished the edges that come into contact with the brass. The dish shape that you refer to on a CZ allows the claw to pop over the rim if you drop a cartridge into the action (not a good plan-you have to be really forceful and probably not good for your gun-if something large and nasty is trying to squish you then ram away but otherwise avoid doing it) The very edge of the claw-the sort of S bend rides up the brass rim as the cartridge comes out of the magazine. When you polish it up, that part of the bolt cycle gets a lot smoother and it is right at the time CoElkHunter was experiencing the hesitation.

I thought I better clarify. In the pic you can see the orange edge. This affects how easily the cartridge slips under the claw and is the source of the slight hesitation or tightness in the bolt as the cartridge rides up. The purple portion is how tight the cartridge is held under the claw. This entire front edge sets the tension with which the claw holds the rim so be careful what you do to it.. I gently removed a bit of material from the orange bit and polished all of the edge as well as the back side of the claw. 600 grit and hand sanding.