I'm wondering about the effect of the standard 458 Win Mag throat on accuracy when using lighter bullets such as 350 or 400 gr. It is my understanding that the standard SAAMI chamber is long throated to accomodate the long 500-510 gr bullets and to help with pressure issues in the heat of Africa. That can't be helpful if one wants great accuracy with the lighter bullets, which in such a throat will have a distance to travel before hitting the lands.

Anyway, I'm just theorizing, because I have little actual knowledge in detail on this. I'm just hopeful that someone does. I've never seen the actual SAAMI specs for the 458.

The specs and theory is one way of looking at it, but there is also practical experience. Someone has to have done some shooting for accuracy with a 458 with say 400 gr bullets, cast or jacketed. I would like to know what results you got.

Then, perhaps some knowledgable person can compare the 458WM and the 450 Marlin regarding the SAAMI throat, and its likely or actual contribution or determent to accuracy, specifically with the short bullets like the 350 gr Hornady or Swift or 400gr Speer or Swift.

Another way of asking it - - if a guy was interested in accuracy, more than speed and not shooting heavy bullets like the 500 gr, which cartridge would be better? Or would it matter which? For what I'm looking for, either cartridge will produce enough velocity. 400gr bullet at 1900 - 2000 fps will be good with me.

The 450 may be the better choice just from the point of more compact rifle, shorter barrel, handier, etc.

Oh yea, I'm talking about bolt action rifle comparison. Lever action is not part of this question.

KB

I have reloaded for 2 different 458 rifles.

The first was a post 64 Super Grade Winchester Model 70. It shot the Speer 400gr and the 350 Hornady RN just fine.

The second was an Interarms Whitworth.
It shot the 350 Hornady RN plenty good.

I have previously owned two M70s and one Ruger # 1.

I only used 400 grain Speers and with 70 grains of 4064, 70 grains of 2208 (Varget) and 70 grains of another Australian powder which I don't think Hodgdon sells but it is like 3031.

The Varget/4064 were right at 2000 and the other load at 2100. Accuracy was superb, continually shooting 1 inch groups.

The main problem with the big freebore is using lighter loads with 300 grainers, hangfires are the order of the day.

quote:

It is my understanding that the standard SAAMI chamber is long throated to accomodate the long 500-510 gr bullets and to help with pressure issues in the heat of Africa.

I had some original Winchester .458 510 grain soft points. They were two diameter bullets.
The parallel sided nose forward of the cannelure was .449.
Whatever the long throat is in a .458 it is not set up to clear these bullets since they were only full diameter inside the case.

I think the Winchester throat was designed to insure rounds would feed into the chamber under all circumstances. Outstanding accuracy was never a consideration.

quote:

Originally posted by SR4759:

quote:

It is my understanding that the standard SAAMI chamber is long throated to accomodate the long 500-510 gr bullets and to help with pressure issues in the heat of Africa.

I think the Winchester throat was designed to insure rounds would feed into the chamber under all circumstances. Outstanding accuracy was never a consideration.

That's what I'm talking about. For whatever reason - heat or chambering - as a DG rifle, accuracy was not the main consideration. So, I'm wondering about that, since I am interested in accuracy - not a match chamber, but with consideration to accuracy over the long throat.

Thanks,
AK

Sent you a PM with access to SAAMI standards.

I have never owned a .458 or .450 Marlin but have owned and reloaded many 45-70s with varying throats.
My longest throated .45-70 never shot particularly well with any 300 grain bullet jacketed or cast. It was throated to allow seating of the 400 Grn Speer in the rear cannelure. It shot spectacularly well with that bullet seated and crimped in the rear cannelure.

If you are going with a bolt gun in a .450 you can have any throat you want. But you could do the same with a .450.
For me the most flexible rifle in a 45 cal is a Browning single shot. There is no feeding issues regardless of bullet weight or shape. There are no restrictions on overall length.
Especially with the tanged receivers you can use almost any conceivable sight. You can use vernier tang sights, folding Marble type tang sights. receiver sights (Williams makes a no drill receiver sight), open sight on the barrel and of course your choice of scope. And the high wall is probably a lot stronger than any bolt gun.

no effect . my 458 AR has a longer throat, and is usually sub moa .. don't overthink it

Yea, Jeff - I'm bad about overthinking stuff. Gives me a headache sometimes.

Looks like I'm committed to the 458 anyway. The gunsmith says he can have it finished by the end of the month. I suppose I'll get the chance to see what accuracy it will produce.

I sure like the thought of a bolt action 450 throated right for the 400 gr bullets.

KB

SR4759 - thanks for the link to the SAAMI site. That's useful.

The 458 sure does have a long throat, as I thought. Like Jeff said, thinking about this too much may cause a guy to just have to get a rifle in 458 and another in 450 Marlin, just to settle the issue.

I've sort of committed to having the 458 finished, and I already have all the parts, and dies, brass, powder and bullets. There are many suitable loads listed for the 458 too.

I think it would be fun to mess with the 450 Marlin too. Obviously it has all the potential of the 45-70 plus some more. That's saying a lot given the endurance of the 45-70 as a popular cartridge for such a long time.

I suppose the same could be said comparing the 458WM to the 45-70. It's just that damn long throat of the 458. I dunno about what you said SR4759 - about having whatever throat I wanted in a custom chamber. That's beyond my knowledge, but I believe the reamer my gunsmith has already has the throat portion built into it. A smith would have to have a special chamber reamer, then do the throat seperately. Then besides that, if a factory round could be chambered, and the throat was wrong, there may be a problem with pressure, etc. I don't know if it would be safe, and I don't know if I could get a gunsmith to cut a non-SAAMI 458 chamber.

I think I'll just go through with the 458, and get started with it. Meanwhile I'm working on the gun fund to build up the cash to buy a bolt action 450 Marlin, or have one made. Making one is just a question of what action to use, which has to be right.

KB

quote:

I don't know if it would be safe, and I don't know if I could get a gunsmith to cut a non-SAAMI 458 chamber.

I guess I have a completely different view.
I buy factory rifles if I am happy to live with a SAAMI chamber. If I am concerned about accuracy then I would make the chamber the way I want it and plan on knowing what brass, bullets and loads are going to be used ahead of time. I know that I would never buy factory ammo for a .458. The cost of getting the chamber opened up to SAAMI standards later is of no consequence.

Yea, I thought about having a chamber cut to my specs, but what specs would that be? Maybe a 458WM chamber with a 45-70 throat, or 450 Marlin throat? I don't know enough to design a throat, and consulting someone? Who - a gunsmith, a reamer maker? They may have different opinion. I don't just need opinion, I need data that I can count on if I'm spending the money. We know for sure that the SAAMI specs are safe. How to sort it out? Then there is the cost of a special reamer, and maybe a seperate throat cutter?

Then in my opinion there are two very basic and important questions which must be answered: Is it safe with factory loads? and Will it chamber factory loads? If it will chamber a factory load, and it's not safe or the safety is not known, then that's a problem. Technically that makes it a wildcat, and should be stamped on the barrel accordingly. That might be OK. I have no need to be shooting the factory loads with the heavy bullets anyway. I think there are some 400 or 450 gr factory loads which may be useful for me, so it might be handy if they were safe. I also want to use standard brass, and standard dies. I see no need to alter the case specs.

Well, I suppose I've talked myself into a potential answer. I'll call Dave Kiff tomorrow and see what he has to say about it. He may have done this before. I found that he was surprisingly knowledgable about stuff like this when I called him and asked about the 9.3 wildcat project I was working on. I may have something to report tomorrow.

It may be worth this trouble, if I can get it right. After all, this barrel was initially cut for a 450 Marlin, which didn't work out. It was finished but I never even fired it because it wouldn't feed right. This was one of those deals where the gunsmith said no problem - feeding would be a non-issue because the action was initially barreled in 350 Rem Mag. I agreed because it was logical. but even after he butchered the feed rails and ramp, it would jam. I was so disgusted that I took it apart with a barrel vice and sold the action and stock, but kept the barrel. I sold a bunch of 450 brass and the dies too.

So there - Jeff - is that over-thinking it enough for you. Can't help myself I suppose, and SR4759 made me do it - it's his fault.

KB

P.S.
After writing the above, I went to Pacific Tool web page, but didn't see anything there for help. I'll have to call. But I looked under wildcat chambers offered on Pac Nor's web site and see 458 Winchester Magnum - no throat. So, at the minimum that tells me that it has been done. The barrel I have is a PacNor. Hummm

Hello Kabluewy:

We provide chambering reamers with special throats on a regular basis. Typically, a customer will send in a dummy round for--in your case--a 458 Win Magnum and ask that we alter the throat of the standard reamer so that the bullet in the dummy will lie just off the rifling when the round is chambered. We'll measure the dummy and will usually be able to get within .005" of the requested throat location.

Keep in mind that when the throat of a chamber is changed from industry-std to a shorter/ tighter configuration, pressure levels and rise time will change. This means that factory ammunition MAY no longer be safe to shoot in the modified chamber.

There are other considerations, as well, and I'd be happy to discuss them if you'd call me at 810-953-0732.

Dave Manson

Dave,
I believe that answers my question. Right on.

Incidentally, you made the 9.3x74R reamer for me that was used to make the bullberry barrel. I was very happy with the reamer, and the chamber, and the barrel. That is a very good shooting rifle, and accurate too. As I remember the specs were CIP minimum, which gave a long throat. That was a bonus in the single shot platform because it allows me to seat the Barnes TSX 286 gr way out there, and still have a little space before it hits the lands.

Thanks for the info.

KB

It is true that the 458 WM is one of those cartridges that has a funnel-shaped throat? From reading the A-Square book, this is one of the throats that prompted the 'load close to the lands' method of increasing accuracy that has been so common over the years. This section of the manual was pretty interesting. In this case, I believe that the _potential_ for reduced accuracy when loading shorter bullets is there, and I think kabluewy has a valid concern (even if in practice it is not apparent in all rifles).

What could it hurt by cutting a .459" or maybe even a .460" parallel throat to this chambering instead of the funnel throat? That throat would accept all bullet types with equal results. Factory ammo would still chamber and fire without any pressure differences, and I bet accuracy would be better for all bullet weights across the board.

I can see where shortening the standard funnel-shaped throat would definitely be a problem. Factory ammo with heavy/long bullets may not even chamber, and if they do, pressures would certainly be higher. I wouldn't want to do this at all myself. A parallel throat cut long enough to accept the longest factory loading without the bullet engaging the rifling would avoid the problem and you wouldn't have to worry about what ammo the next owner might use. Just pondering this question further...

The proper throat for good shooting in 45 caliber rifles is well know in BPCR circles. Pedersoli uses a version in their production rifles that works well.
Because of the expense of jacketed bullets in 45 caliber anyone shooting in much volume will probably need to shoot cast bullets. The cast bullets can be varied to match the throat. There are very good mold makers such as Paul Jones, Steve Brooks and others that can make a mold to work with your throat too. However the standard .458 throat is a poor one for optimum accuracy.
45-70s often have little or no throat from the factory yet they use and often give spectacular accuracy with the long 500 gain parallel sided cast bullets, while still having a throat that works fairly well with short bullets. The "throating is often in the bullets". That is the long parallel sided bullets are only .449 to .450 on the nose.
Most modern .45-70 land diameters are a little bigger than .450 due to the shallow modern rifling. A custone mold will have a .450 nose diameter and the driving bands step up from .452/.454 to .456 to finally .459 or .460 at the base.
This effectively puts a/the gradual lead in on the bullet.
There is no reason to live with the standard .458 throat if you prefer something that will give better accuracy.

If you decide to go the way of a custom chamber ask the shooters here to measure the nose of all of their parallel sided African type .458 bullets. I think you will find they are .448 to .459 on the nose and as such are just bore riders ahead of the the cannelure. Thus the .458 has little to no rifling engagement for over an inch of jump.

SR4759,
It’s interesting that you use the name SR4759, because that’s the powder that I’m planning on using for load development. This idea of the 458 WM got momentum as a specialty rifle from the get-go. So it might as well be really special. My experiment is to develop a load that is sub-sonic, using 350 – 405 gr. Bullets. Part of the “problem” is that the barrel I have is 20” twist. I got it figuring the 45-70 worked well with low velocity loads for over 100 years, so where is the issue requiring a faster twist? I could be wrong about that, but what’s new about that? It certainly won’t be the first time, and I’ll get over it. Hopefully it won’t be a problem at all.

So, basically that rules out the use of any bullet over 405gr anyway. I have a better chance of stability success with lighter bullets, but I don’t want to go lighter than 350 gr.

The next thing is that I’m considering a suppressor for the rifle, with a 16-18” barrel. So, that pretty much excludes cast bullets – I think. That’s because I don’t want to have to worry about baffle strike from a piece of lubricant or lead.

That narrows it down - it’s jacketed or solid bullets. I think that even if the throat was really short, that would still leave lots of options, including near full power loads with something like the Barnes 350 gr TSX or the Swift 350 or 400 gr, or maybe the Speer 350 gr. That’s a lot of versatility. I saw a hunting show on TV recently about hunting Africa planes game,and they had suppressors on their bolt action rifles. The rifle could be servicable in Alaska with near full power loads and 350 - 400 gr bullets, without the can. Mostly it's a hog rifle for hunting from a stand with shots 100 yds or less. And cast bullets could be used too, but just not with the suppressor attached.

I don’t know whether the suppressor could or should be used with full power loads or not. That’s something I’ll have to ask the can maker about. It may be moot anyway since I think it's not practical hauling around in the Alaska bush with the can attached, mostly because of the weight of the can. Also, I haven't checked but it may not be leagal to hunt with a suppressor in Alaska anyway. So versitility is important to get enough use out of this rifle to justify putting it together. For the next few years I'll get to hunt down south maybe average once a year. I suppose it's possible to get a muzzel brake that fits the same threads as the suppressor, and switch.

I called my gunsmith and told him to hold off chambering the barrel until I got a handle on this issue.

The thing about this barrel with the 20" twist is that I know it will work with some bullet/load combo, perhaps near full power, so I'm not too worried about it being the wrong twist rate for the sub-sonic project. Just in case it doesn't work out, I won't be cutting the barrel shorter or messing with the suppressor until it has well established with a good accurate sub-sonic load. If I can't get to do what I want, then I can think about a faster twist barrel, if I want to continue with the sub-sonic/suppressor idea. If necessary I'll use 350 gr bullets, or maybe the Barnes 300 gr designed for the 45-70. They will provide plenty of power for what I'm wanting to do with this rifle, and I can't imagine that such short fat bullets won't stabalize with a 20" twist, even sub-sonic. There are several examples of similar bullets used in the black powder sabots, and as I remember the twist on those rifles is generally 1 in 28", and the 45-70 has been used with apparant success for a long time.

KB

I use a lot of SR4759 in the 45-70 and 40-65 with cast lead bullets at 1000 to1300 FPS (black powder velocities). The combination is very accurate in multiple rifles and is a lot of fun at the range. The loads are fired just for the sake of fun and nothing else.

quote:

so where is the issue requiring a faster twist?

In the 45-70 and such there is no requirement since the 45-70 was just designed to kill humans. The 458 was designed for African use and I am sure the designers were hoping to insure the bullets did not tumble during penetration of large game. I think this is the cause of many of the bent banana shaped FMJs recovered from large game. Your use of the 20" twist may compromise the original design of the 458 if it is used with long heavy bullets intended for deep penetration. For light bullets use the 20" twist is probably much better but so would a smaller case.

For subsonic use you might look at IMR Trail Boss and a smaller capacity case. In this regard you could chamber with a shorter belted round and if you were not happy make it longer.
If you decide on a 458 case your smith could start you out at .45 X 1.75 or so. He just chambers shallow and then bores the belt recess.
If you don't like it you can increase the case length.
For reference a 45-70 gives about 1200 fps with 24 grains of 47-59 and a 500 grain bullet.
This is a little more than 50% of the case capacity. I would guess that pressure is under 20,000 PSI. Accuracy is excellent when I have a good day at the range with groups getting down in the 1.5" range. My barrel has an 18" twist.
These loads would shoot to 1000 yards without tumbling.

Thanks for the info SR4759.
If you can get a 500 gr bullet starting at 1200 fps to be stable out to 1000 yards, surely I can get a 350 or 400 gr bullet to be stable to 150 yds. I doubt penetration will be a problem on deer and hogs, with sub-sonic loads, but the bullet will probably act like a solid, except for maybe the Barnes 300 gr with that huge hollow point. If I use the rifle on Alaska stuff such as moose or bear, it will be with near full power loads 350 - 400 gr, and at close range, so again I doubt stability or penetration will be an issue.

Hornady web page load data shows some cast bullet loads for the 458 using Trail Boss. Since they are low pressure, I suspect that substituting jacleted bullet of about the same weight would be OK.

I have given this smaller or shorter case a lot of thought. Sure, by some margin a smaller case would technically be better. That's why I'm not wanting to use the Lott. Going with the 458 caliber bullet came after a lot of thought, since good bullets in the right weight range and at the right price are readily available. Also, a .458 still has enough thump at 100 yards, starting sub-sonic, to do the job on deer and hogs. Versitility is there by using faster loads with well constructed premium bullets, for the situations of hunting really big game.

I think a lot of guys make the mistake of thinking of only the technicalities of the cartridge, and just don't think about the platform or the whole package until later. I have made that mistake, hence the flopped 450 project. Single shots simplify this issue, but I don't want a single shot rifle.

So, simply I'm not willing to experiment with short 458 brass. It's just too much trouble. I picked the 458 WM because it practically jumps into the chamber slick as glass, feeding from my Ruger action. Take a 450 Marlin and try the same thing - same action - and it jams. It's the angle of the dangle. And the magazine would have to be blocked at the rear, or at least the cartridges loaded so they stack up front. What's needed IMO for the 450 Marlin in a bolt action is a push feed type bolt. I just don't have one. I suppose I could sell what I have and buy one.

Anyway, I just figured the advantage I would get by trying to use a shorter case, such as the 450 Marlin, would be offset with other problems. Besides the 458 WM seems to adapt well to a great varity of reduced velocity loads.

I'm still willing to consider using the 450 Marlin case, if I can come up with a great platform - rifle - to use it in. I think the 450 is the only alternate option.

KB

The first 45 caliber rifle that I fired was a .458 X 2" built on a FN98 commercial action by Atkinson & Marquart for lead bullet shooting. Basically all it was/is a belted 45-70 and precursor to the 450 Marlin.
The only thing Marlin did was use that odd ball belt to prevent it from being loaded into something like a 300 Weatherby chamber. The owner of the A&M rifle was at the range a lot and he never had any feeding problems with it.

Being a broke college student my first attempt at a 45-70 was a Siamese Mauser about that same time period - 1972. It was relatively easy to get the Siamese Mauser to feed the large rimmed 45-70 case. I probably worked on it less than 2 hrs going slow. My point is that any decent gunsmith can make the .458 X 2" or 450 Marlin feed from your action.
I personally feel the .450 Marlin is a bastard round and the 458 X 2" is the more legitimate to use. I have shot some sort of 45-70 for more than 35 years and I have never fired a single round of factory ammo. I can't even imagine buying factory ammo for a 45 caliber rifle. That being said, for me it comes down to the comes down to brass availability. Brass for the 458-2" is was more available than any other 45 caliber rifle brass. Even more available than the 45-70. All you do is cut off any common belted magnum brass...
Brass for the 450 Marlin will always be an odd ball, hard to locate and expensive. A good example is another Marlin offering the .444 Marlin. Brass for the .444 now expensive and hard to find.

These are the kind of conversations that have cost me money in the past. Many years ago, I had a couple of the Siamese actions and planned on using one at least for a 45-70. Just couldn't get it going. Incidentaly, it didn't feed worth a darn as it was but that doesn't mean it couldn't have been skillfully altered to feed good. Since then I have handeled several "custom" 45-70 Siamese Mausers, and checked out the feeding, and everyone of them was crap for feeding. They would jam, or the cartridges would pop out of the feed rails, or fail to eject, or all the above. There may be some good feeding Siamese Mausers out there. There are lots of guys who say theirs is good. It's just that I have never seen one. I have seen some that guys say their rifle fed good, but when I tested it I could not see how they could truthfully say that. It's a mystery to me - something I can't reconcile.

I have heard this conversation many - many times about any decent gunsmith can get it to feed. I have spent a lot of money over such words, and was dissappointed. As I'm writing this, I'm trying to think of one instance - just one - where success was achieved on any rifle I have ever had in fixing a feeding problem. That's odd - I can't remember one. I'm really trying -- but I can't remember one. Whads zup wid dat bro??? Maybe bad memory. Humm. But I do remember the failures. And I clearly remember the guns that the owner said fed good, which clearly didn't. It's an odd thing, because I'm sure the guys were not lying, but it just looked to me that they didn't know what they were talking about. In some cases, when I showed them, they said they had not noticed that before. In maybe one or two cases the rifle did appear to feed for them, but had hitches when I tried it.

Could be my first success is in the making, since I've got one rifle being put together that will require some finess on feeding. We shall see...

One may think I'm very picky about feeding. I don't think so. It either feeds well, or not. To me it's a black and white issue. If I can cause it to jam, or fail to eject (which is a jam) under normal operations, then in my book it doesn't feed well. Some rifles will feed with pointed bullets and maybe jam with round nose or flat nose. That maybe OK, if a guy is willing to live within its limitations.

On the Mauser, with the 458x2", could be that it fed good in that rifle. Personally I've never seen a Mauser that fed a 458 WM good enough for me. There is always some little hitch, maybe with the second one down, or the final cartridge. Maybe the one against the right feed rail is just barely hanging on and on the verge of poping out of the magazine pramaturely, or actually pop out sometimes, or as with many Mark X magnum actions, fails to kick out the fired case with authority. Most guys seem to not notice it, or don't mind, but I do, and it annoys me. All my rifles feed very well, or they take a hike.

The thing is that it would cost me a lot of money to get a Mauser action modified to feed a magnum cartridge properly in my judgment, and I would have to actually see it and test its feeding before proceeding with the project. My confidence level on that is obviously low, based on experience. On the other hand, I can take a Ruger action with factory magnum bolt face and magazine , or a CZ 550 medium magnum, or a Winchester 70 with factory magnum bolt face, and I can test them and I can clearly see and feel the flawlessness of their function, and clearly see that no gunsmith work is needed for feeding. Why in the world would I take something that has issues and try to make it work out, when I have actions already with no such issues?

This way, my probability of being pleased with the gunsmith's work is not deminished with a bum action, and I know it will feed before hand, and the gunsmith can concentrate on other aspects of the project.

I feel that the 450 Marlin cartridge makes the wildcat 458x2" the bastard. There are lots of cartridges in use that brass is somewhat uncommon. I think the 450 Marlin is a good idea, and a good cartridge for what it is. The 376 Steyr is a good example too. Some people really like it, and brass is limited in source, but there is no denying that it is a good cartridge. It's just not on my menu, since I like the 9.3x62 better.

KB

P.S. All that said, I am listening to you. So, I'll ask my gunsmith to try feeding the 450 Marlin cartridge in the action he has. It's a Ruger long action, and I know it feeds the 458 WM very well, but I have no problem using the 450 Marlin in that action - if it feeds well. He can actually screw the barrel into place, since the previous action was also a Ruger, just it was a short action. In that case I made the assumption that surely "a good gunsmith could make it feed", and it didn't work out. One would think that a Ruger short action that had a factory barrel in 350 Rem Mag would be very close to a no-brainer for rebarreling to 450 Marlin. Well it ain't that simple. The fat round nose or flat nose bullets cause a problem, and no shoulder causes a problem, and the short length of the cartridge causes a more extreme angle as the cartridge gets at that critical point of poping out from under the feed rail, while the rim stays behind the extractor claw. The angle is not so much with the 458 WM, and it seems to glide out of the feed rails, and the rim cleanly slips under the extractor. When I tried it, the flat nose or round nose bullets don't seem to make much difference with the 458 in that action, because by the time they get to the place where they may hit the breech of the barrel, they have already kicked out of that angle, and are aligned close with the bore. Also with the 458 WM, the rim of the case and the lip of the extractor don't argue - they mate - because the angle as it slides in is not too much. That's why I said a push feed short action may be the best choice for the 450.

This morning, before getting busy with other things, I decided to try something. I have a FN bolt with a magnum bolt face that I had been thinking about selling, but it's really a good one - like new. I also have a new Charles Daly receiver which I had also been thinking of selling because it doesn't feed standard cartridges such as the 8x57 or 30-06 very well.

Anyway, I put the two together, and a standard FN bottom metal, and tried feeding some 338 WM shells. I'll be darn - they feed really well. I'm surprised. They stay in the magazine as they should, and as pushed forward they pop up at just the right place, and the tips stay well aligned with the center of where the chamber will be when it has a barrel. I can see this action will work pretty darn good with a magnum.

So, your silence, and my curosity has proven me wrong. Now I have an example of a Mauser action that feeds magnum cartridges good, and potentially very well with a little work. The extractor is a little tight for example, but the feed rails look good.

Regards,
KB

The Atkinson & Marquart rifle was also built on an FN commercial action so I am sure they started with the short magnum version (as opposed to the version made for H&Hs). I would have no reason to doubt that A&M did not make a rifle that worked perfectly. They even made the barrel used on it.

Any project requires:
1.Good research and planning.
2.Perseverance to see it through.

There are a lot worse combinations than the .45-70 in the Siamese Mauser.

SR4759,
Agreed on all stated above.

Sometimes we just luck out despite the lack of good research, planning and perserverance. But often lack of planning and research, causes perserverance to become the most important factor, hence the concept of "making it feed". However, experiencing a few aggrivating mistakes, I have learned the value of all three, but also that's part of the fun to me. I'm sure that I over think it as Jeff said, but that's ok too. Mostly, lately I have been trying very hard to stay close to the motto of keep it simple. I know that feeding is an important issue for me, and poor feeding will cause the whole project to crash for me. That's why now I make sure (as much as possible) the action will work well with the chosen cartridge before proceeding.

Yea, I surely agree that there are lots of worse combos. Take the 45-70 on a Mosin Nagant or Lee Enfield for example. At least the Siamese is a real 98 Mauser action.

I have a friend who likes odd cartridges, and he has some 450 Marlin ammo. So, I took the firing pin assembly out of the bolt, and tried feeding some 450 ammo through the Mauser action with the magnum bolt face. Although it feeds the std magnum ammo like 338 WM very well, with the 450 just terrible is adequate description. Nevertheless, it's good to have a Mauser action around with a magnum bolt face, and it feeds std magnums well, just in case some must-have project comes to mind.

So, I still don't have an alternate plan besides the 458WM with the special throat, on the Ruger action. Considering the whole package, it's still the best option IMO.

I did learn recently that Steyr offers the 450 Marlin in their so-called Big Bore, with a 14" twist. That could be really interesting. Costly, but good to go right out of the box, trigger and all.

The bonus of trying the feeding of some of my actions today is that I also made another discovery. Over time, I had previously tried the 376 Steyr cartridge in several Mauser actions that I had, and couldn't find one that looked like it would feed right, without some serious tweeking, and I could get only three down. Well, I have a Blackburn bottom metal unit, std 30-06 size, that I have been trying to figure on what to use it on. I want it to be something special. My friend also had some 376 ammo, so I put the Blackburn box on an early Mk X action, (Herters J9 I think) and it feeds the 376 ammo great off the rails and ramp. Of course the bolt face will have to be opened. And it allows 4 down, with barely but enough room to easily close the bolt over the top of that 4th round. That's something I didn't expect, and had written off the 376, although I really like the cartridge. Maybe I'll reconsider. I just have too many projects, so hopefully I'll get to it.

I wonder how it feeds the 9.3x62? Humm

KB

The dia of the throat is much more important than the length. If the throat dia is .001" over bullet dia, within reasons you could have a very deep throat and still get excellent accuracy. Whereas if you have a sloppy throat, the gun might only group when the bullets are crowding the lands.

My first 458 lott had a very long throat, I never mesured it, but when I seated some 450 gr X bullets way out there, I never hit the lands. That said, I loaded both 350 gr speers and hornadies to 458 win mag velocities, and they would group 3 shots into 1 1/2" at 100 yds, which isn't bad for iron sights.

quote:

Originally posted by Paul H:
The dia of the throat is much more important than the length. If the throat dia is .001" over bullet dia, within reasons you could have a very deep throat and still get excellent accuracy. Whereas if you have a sloppy throat, the gun might only group when the bullets are crowding the lands.

That's good to know. I can get my gunsmith to measure his reamer's throat as well as the length. Chris at PacNor said he could cut the chamber, then make the throat match whatever handload dummy round I sent him.
KB

quote:

Originally posted by Paul H:
The dia of the throat is much more important than the length. If the throat dia is .001" over bullet dia, within reasons you could have a very deep throat and still get excellent accuracy. Whereas if you have a sloppy throat, the gun might only group when the bullets are crowding the lands.

My first 458 lott had a very long throat, I never mesured it, but when I seated some 450 gr X bullets way out there, I never hit the lands. That said, I loaded both 350 gr speers and hornadies to 458 win mag velocities, and they would group 3 shots into 1 1/2" at 100 yds, which isn't bad for iron sights.

A lot of people say this when many rifle chambers have no real throat with a diameter. The 458 SAAMI throat is a long cone. The 45-70 is a short chamfer to short cone. If you happen to have a large diameter parallel sided throat at least with cast bullets you can often use a bigger bullet to take up the slop since the soft bullet just sizes itself in the barrel.
What you find with 45 caliber rifle jacketed bullets is often the 400 FN bullets (Speer, Rem and Win) have a longer bearing surface than the 500 grain bullet. The 500 grn bullets at least those from Winchester were 2 diameter bullets and only had a short shank that was groove diameter. The nose of the big Winchester bullet was under bore diameter. This resulted in the bullet have very little nose support for more than an inch of travel.

Planning the bullet you want to use and then having the right throat reamed will give you the best chance of accuracy with short jacketed bullets.

I have about made up my mind to let PacNor have another try with the chamber and throat. With that issue settled, it's just deciding on which jacketed bullet. That's a best guess at this time, without having tried a variety. I'm thinking the Speer would be a good bet.

KB