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View Full Version : What's the difference between 300 win mag and 300 weatherby Mag


bigrebnc1861
February 19, 2010, 02:06 PM
I know a little bit about the 300 win mag but not real familar with the Weatherby Mag. Is there that much difference? The reason I am asking is that I can get a used Remington 700 .300 Weatherby Mag with slighty scratched woodstock no scope for $299.00 Or I can get a Salvage 111 .300 Win. Mag. 349.00. The 111 is what I have been looking for but I have heard sonme good thing about the 700.

Thanks in advance for any reply's

themusgrat
February 19, 2010, 02:12 PM
Ya the 700 is good but I wouldn't expect it to be any better than the Savage. The .300 Weatherby is basically just more powder, so a slightly heavier .30 caliber magnum charge. It's a great round, but I'd have to ask myself if it's in reality any better at all than the .300 winmag, which can kill anything in North America with ease. The Weatherby will shoot a little flatter, go a little faster, and carry a little more force. The downside is more recoil/noise than the .300 winmag. Also ammo is not nearly as widespread for it.

.300 Weatherby Mag
February 19, 2010, 02:29 PM
The ammo in plenty widespread in country in which it shines (Wyoming)...

uncyboo
February 19, 2010, 02:30 PM
Chuck Yeager described the 300 WBY as the perfect elk round.

The difference in performance between the Win and WBY is pretty small. Some people like the WBY for the longer neck, but the Winchester version has proven itself to be plenty accurate, despite it's short neck.

The WBY ammo will be a good bit more $, unless you handload. Then the difference will be nil.

So, the 50 bucks you save with the Remington will be negated very quickly unless you handload. However, I am a 300 WBY fan, as well as a 700 fan, and I handload. The choice would be a no brainer for me....

themusgrat
February 19, 2010, 03:15 PM
Ammo might be more widespread in places, but I'd bet that there's no place in North America that normally carries more 300 weatherby mag ammo than 300 winmag. But don't let that stop you. If you're going to casually use it to hunt a few times a year, you'll be going through 2 or 3 boxes anyways, so it's no big deal. If you're going to really get to know it, you'll prolly be handloading anyways. But the ability to go to any sporting store and pick up a box of cheap ammo is a plus for any gun, if just for the brass.

bigrebnc1861
February 19, 2010, 03:54 PM
Thanks for the help. Now I see why the Rem. 700 is so cheap. The price of ammo is more then I would have first thought. Hornady was the cheapest at 45.00 for 20 So due to ammo cost I guess I will pay a little extra for the Savage 111.

uncyboo
February 19, 2010, 04:07 PM
OK now tell us where this $300 Remington is.............

Please.

Big Bill
February 19, 2010, 04:09 PM
What's the difference between 300 win mag and 300 weatherby Mag?
Probably about $20 per box of 20 rounds. :)

bigrebnc1861
February 19, 2010, 04:53 PM
uncyboo It's at a pawn shop in Concord North Carolina. I may still get it. but I am leaningmore towards the Savage.

Billy Tasso
February 19, 2010, 09:00 PM
I can tell you one thing, the Weatherby magnum will not only rattle your teeth, it will curl your toes with its recoil. The recoil of the .300 win. mag. is considerably less than that of the Weatherby magnum and the difference in the performance is not enough to justify punishing yourself to that extent.
Just one man's opinion that has shot both and hunted with a Remington 700 in .300 win. mag. for about 26 years now. Besides, I've heard that the new Savages are fine shooting rifles and wouldn't hesitate to purchase one.

.300 Weatherby Mag
February 19, 2010, 09:48 PM
^^^

No whining.... It's not that much more recoil than a win mag.....

pwillie
February 19, 2010, 09:53 PM
300 Weatherby,you want be disappointed! Its a confidence builder when you know you have the best...Recoil is near same...Much faster!...and a lot flatter..

warbirdlover
February 20, 2010, 12:15 AM
But now Hornady is making .300 WM ammo that matches .300 Weatherby....

Superperformance .300 WM data.

http://www.hornady.com/store/300-Win-Mag-150-gr-GMX-Superformance/

Normal .300 Weatherby data.

http://www.hornady.com/store/300-Weatherby-Mag-150-gr-InterBond/

rantingredneck
February 20, 2010, 12:19 AM
Probably about $20 per box of 20 rounds.

My thoughts exactly. Saw a box of Remington Express Corelokt .300 WBY Mag in a TN Walmart for 51.99 a box.

About twice what the equivalent .300 Win Mag ammo goes for I think.

.300 Weatherby Mag
February 20, 2010, 01:41 AM
The full power stuff is the weatherby factory ammo...

Compare the 180 grain superformance hornady stuff to 180 weatherby factory ammo...

Hornady: 3120

Weatherby (Norma): 3250

Most commercial 180 grain .300 win mag ammo is around 2960 FPS....

Scorch
February 20, 2010, 03:55 AM
I use a rule of thumb: any load for the 300 Win Mag, the Weatherby will beat by 200-300 fps. Takes 10% more powder to gain 5% more velocity. If the 300 Weatherby is worth the extra recoil and noise to you, it does shoot pretty flat. 300 Rem Ultra Mag runs about the same velocity.

handlerer
February 20, 2010, 04:49 AM
I have reloaded and used both 300 WM, and 300WBY. With bullet weights 180gr and under the difference is really insignificant. The longer case neck allows the Weatherby to seat and chamber longer heavier bullets and fire them faster. I am and always have been fascinated by the highest intensity rounds. I started reloading for 7mag and 300WM in 1976. I now reload for 300WBY, 340WBY, 6.5x55, 223, and 44MAG. I haven't tried the Hornady brass, but know the Norma made Weatherby brass to be much superior to the Rem brass which I have tried and is not durable at the pressures that Wby factory brass can be loaded to. My latest favorite load is the 190gr Hornady JSPBT, at 3100fps, chronoed. If you are going to reload you would be best served and satisfied going with the 300WBY,IMO.

Suwannee Tim
February 20, 2010, 08:23 AM
Looking at the ballistics you find the Weatherby uses a lot more powder to get a little more velocity and this is more true with heavier bullets, 180s and up. This extra powder which is not producing energy in the bullet causes substantially more recoil. I'd go with the Winchester magnum. Weatherby is notorious for overstating their velocities. Look in loading manuals for honest information.

earlthegoat2
February 20, 2010, 08:27 AM
Perfect elk round?

I guess I will take the 30-06 with half the amount of recoil not loss in hunting accuracy and enough effective range that 98% of all hunters would not be able to extend ethically with the 300 Weatherby.

crghss
February 20, 2010, 10:02 AM
For that price I'd have to buy both.

Fat White Boy
February 20, 2010, 11:34 AM
If you are going to shoot 180gr bullets, get a .30-06...My son has a Model 70 in .300 Win Mag. We reload for it using 200gr Sierra bullets. When we go to the range, he will shoot it 3 or 4 times then put it away. And he weighs 215lbs.

uncyboo
February 20, 2010, 12:36 PM
For that price I'd have to buy both.

This is the best idea yet.

uncyboo
February 20, 2010, 02:16 PM
Perfect elk round?

I guess I will take the 30-06 with half the amount of recoil not loss in hunting accuracy and enough effective range that 98% of all hunters would not be able to extend ethically with the 300 Weatherby.

I was just quoting Yeager. '06 is of course a great round, but the OP's question was based on 300 Win and 300 WBY.

handlerer
February 20, 2010, 05:10 PM
The loading manuals are always conservative, I have dozens of them and I can beat anything they show with my own handloads. Yes, Weatherby or any 30 cal magnum cartridge has considerable recoil. My 16 year old son, all 130lbs of him, fires 16-20 rounds through the 300 and has never complained about the recoil, he gets very good groups too. My point is you can learn to accommodate recoil, with practice. Having reloaded both, I find the WBY superior ballistically in every way. I have taken two large mule deer with the WBY using 180gr Triple shocks and the results are devastating! Neither moved a yard. The brass is cheaper for the 300WM, but also inferior to the Norma brass, you will get fewer reloads using WM brass, unless you use milder loads than possible. All said though, there is isn't enough difference to make an issue over, both will perform on any large game on this continent.

CarbineCaleb
February 20, 2010, 05:25 PM
Quote:
What's the difference between 300 win mag and 300 weatherby Mag?


Probably about $20 per box of 20 rounds. :)



Another plug for the more common and cheaper cartridge. :)

Suwannee Tim
February 20, 2010, 07:30 PM
For every additional grain of powder you put behind a particular bullet you get less result in bullet energy. For example, a 30 carbine is very efficient, a 30-30 somewhat less efficient, a 30-06 even less so, the magnums even less efficient. The powder energy not transformed into bullet energy goes several places, flash, blast, barrel erosion and most notably, recoil. The point where more powder is not worth ever smaller increase in bullet energy is subjective and will vary by individual. For me that point comes between the Winchester magnum and the Weatherby magnum. I loves my Winchester magnum:D. Don't wants no Weatherby:eek:.

SeekHer
February 20, 2010, 07:57 PM
Recoil is relative to stock design, rifle weight, retardation and redirection of the energy...

Kicks a little too much for you, stick a Mercury Tube in the butt and/or forearm and/or wear a recoil shield like a McCoy or a PAST and/or add a good new material LimbSaver, KickEeze etc. recoil pad and/or put a little less powder in the case or lastly get a whole new stock...

Wow, $20 a box more...two boxes would be $40 then or $1.00 per round more...Say 10 rounds to sight in, 5 rounds in case of jars to the system later on that leaves 25 rounds and then even if you used two rounds per hunting season that's 12½ years of hunting...Ok, if I was shooting long range precision matches it would make a difference but for Joe Average hunter, no! Then again if I was shooting matches I'd be reloading so it really wouldn't matter one iota to me...

My question to the OP is why either cartridge? Are you in a locale that long range shots for game are common? In mean if the longest shot that ever would present itself to you is 200 yds then any .25,.26, .27, .28 calibre would do it and with lots less recoil and noise...

GeauxTide
February 20, 2010, 09:50 PM
The 700 won't have the Weatherby 3/4" freebore, so there goes the 150fps difference over the Win Mag. Cases for the Win are much less expensive. In a 700, the recoil of the WBY will be the fastest you've ever experienced. Have a scope with almost 4 inches of eye relief and a big neoprene ring.

sc928porsche
February 21, 2010, 02:31 AM
The 300 WBY is a bit faster than the 300WM with all things being equal. The WBY seems to like the heavier bullets better. It is similar to comparing the 308 to the 30-06.

Weatherby ammo is very expensive compared to the winchester, but the cost can be dropped by reloading. Once you have the brass, the WBY only costs a penny or two more per round because the components are the same and its only the difference in the amount of powder.

With either chambering, stay away from short barrels. Both of them need the length to burn the powder.

There isnt a lot of difference in the recoil of the two. Just make sure that the rifle is held snugly into the arm pocket and you press your cheek firmly against the stock. If you dont, you will get 300 magitus.

Suwannee Tim
February 21, 2010, 01:29 PM
I'm working from memory here as I am renovating the room where I reload and my reloading manuals are all packed away, you can refer to your manuals to confirm what I say. The "overbore" magnums, the Weatherbys and the like shoot heavier bullets at about the same speed or slightly faster than the "mainstream" magnums, the Remingtons and Winchesters. Where the overbore magnums gain an edge is with the light bullets. Example, the 300 Weatherby magnum will shoot a 110 grain bullet several hundred fps faster than the Winchester but they shoot a 220 grain bullet at about the same velocity. Away from the extremes, the Weatherby will shoot a 150 somewhat faster and a 180 a little faster than the Winchester. This is true of 7mm Remington versus 7mm Weatherby, 264 magnums and others. Who wants a 300 magnum to shoot 110 grain bullets from? They are fine for some fun but have little practical application. The serious bullets, the 180s and up you get little or no gain from an overbore magnum. See for yourself look up various calibers in reloading manuals.

mr.matt
February 21, 2010, 03:32 PM
velocity is not everything in hunting. either round will kill deer and elk just fine. Buy the gun that's cheaper to shoot - the whole point here is to go shoot and have fun hunting. If you can (and want to) afford to spend the extra on a silly 100-200fps then go for it.

For reference I own a 300WM, 270WSM, had a 300WSM, and some other smaller round guns. In comparing the ballistics and the intended use there really isn't any "good" reason to get the WBY.

bamaranger
February 21, 2010, 10:03 PM
I haunt a public range near my home frequently. On more than one occassion, I've picked up 300 Win cases, that have been fired in 300 Weatherby rifles.

I've dubbed the resultant fire formed cases the 300 Mag Shortneck.

uncyboo
February 21, 2010, 10:11 PM
If you can (and want to) afford to spend the extra on a silly 100-200fps then go for it.

To a lot of us, there's nothing silly about 200 FPS............:D

For reference I own a 300WM, 270WSM, had a 300WSM,

You bought 2 of the Winchester short-mags and then tell someone to buy whatever is cheaper to shoot???

I'm just jackin' with ya I hope you know that...:D

okiefarmer308
February 21, 2010, 10:59 PM
My first post here. A couple or 4 years back I was at a gun show and saw one of the prettiest custom stocked rifles ever. The guy said make me an offer,I popped off($200) and was the proud owner of a supposedly 300 win mag built on a 1917 Enfield action. Worse yet it was left handed stock,I can shoot either handed but am primarily right handed. Took it home prepared for mule like kicks. It did not kick as bad as many 30-06's I have shot. It is a very heavy stock,I will admit. After 3 shots I noticed the shoulders looked funny,yep it was stamped 300 win mag but is a 300 Weatherby magnum. It took a couple of trips to an old gunsmith that was sloooooow before it was figured out. Eddystone action so he magnifluxed it to be sure it was safe. My question is,I have a buttload of 300 win mag brass,would it be safe to fire form and just use them? I know the neck would be shorter but would it be feasible?

uncyboo
February 22, 2010, 11:34 AM
My question is, I have a buttload of 300 win mag brass,would it be safe to fire form and just use them? I know the neck would be shorter but would it be feasible?

If my math is correct, you would have almost no neck left. The neck on a 300 Win Mag is .264, (already shorter than caliber). The difference in total length of the 2 cartridge cases is .205. So no, I don't think this would work at all.

WIN71
February 22, 2010, 01:06 PM
Cost, Speed, and Pain with the nod going to Roy.

okiefarmer308
February 22, 2010, 01:55 PM
Unckyboo(hope I spelled it right).thanks for the opinion. The blown out shoulders leave about 3/8 inch neck to try to seat a bullet, so it would have been a problem with seating.

glazer1972
February 22, 2010, 02:53 PM
.300 Weatherby is good but I would stick with the .300 Winchester.

precision_shooter
February 22, 2010, 03:01 PM
All of this, weatherby is 200 fps faster.... and weatherby can handle heavier bullets stuff sounds a lot like the 30-06 vs .308 debate. And we all know how that turns out...

The 300 win mag (.308) will work just fine for anything you need in North America. Ammo is cheaper and more plentiful than the weatherby.

It really comes down to personal preference....

uncyboo
February 22, 2010, 04:16 PM
The blown out shoulders leave about 3/8 inch neck to try to seat a bullet

This just does not sound right at all. The Weatherby case is 2.825 long. The Win case is 2.620 long. That's a difference of .205. The neck on the Win. case is .264. Shade-tree math says that leaves .059 neck left after you blow out a Win. case in a WBY chamber. I say shade-tree because it does not take into account the slight differences in body diameter at the shoulders, the venturi radii on the Weatherby case, etc. My point is, the Winchester case is just barely as long as the Weatherby case is at the neck junction of the latter.......

uncyboo
February 22, 2010, 04:20 PM
All of this, weatherby is 200 fps faster.... and weatherby can handle heavier bullets stuff sounds a lot like the 30-06 vs .308 debate. And we all know how that turns out...

The 300 win mag (.308) will work just fine for anything you need in North America. Ammo is cheaper and more plentiful than the weatherby.

It really comes down to personal preference....

While all of this is spot on, the OP's question was was it worth the screamin' deal of $299 for a Rem. 700? You'll have to admit, that's a great price. If nothing else, I'd pick it up just for the action. You could always get a little for the barrel and stock if you just use the action for a new build.....

And the biggest detriment to the WBY chambering is the cost of factory ammo (and brass).

okiefarmer308
February 22, 2010, 04:55 PM
Uncyboo,here is a link showing what a 300 win mag looks like with the shoulders blown out,thats what mine look like.Hate to doubt the math but seeing is believing.

http://www.larrywillis.com/caution.html

precision_shooter
February 22, 2010, 04:56 PM
While all of this is spot on, the OP's question was was it worth the screamin' deal of $299 for a Rem. 700? You'll have to admit, that's a great price. If nothing else, I'd pick it up just for the action. You could always get a little for the barrel and stock if you just use the action for a new build.....

Yes, it is a good deal as far as just the price of the rifle is concerned. As long as the bore and rifling are good.

And the biggest detriment to the WBY chambering is the cost of factory ammo (and brass).

This is why I would go with the Savage. The cost savings alone in ammo cost will more than pay for itself. May be 1 year or 5, but saving $20 a box on ammo will add up in a hurry. Say you shoot 5 boxes a year between practice/range time and hunting, then you already saved the $100 difference in the cost of the rifles. Plus, with the Savage you are getting a brand new rifle and know it has not been abused...

uncyboo
February 22, 2010, 08:15 PM
The cost savings alone in ammo cost will more than pay for itself. May be 1 year or 5, but saving $20 a box on ammo will add up in a hurry. Say you shoot 5 boxes a year between practice/range time and hunting, then you already saved the $100 difference in the cost of the rifles. Plus, with the Savage you are getting a brand new rifle and know it has not been abused...


All very good points. I tend to take for granted that serious shooters usually handload. I didn't go back and read every post, so I'm not sure if the OP does or not. Handloading usually takes the ammo cost out of the equation, at least to a huge degree. Yes, some brass is initially more spendy, but averaged over several loadings this is a relatively small cost.

I have handloaded almost as long as I've been shooting, over 25 years. I know I have saved enough in ammo costs to buy a couple of rifles, and got to shoot more along the way.

warbirdlover
February 22, 2010, 08:30 PM
If you don't like these two choices you can always get the .300 Rem Ultra Mag or the Weatherby .30-.378 (OUCH!!)... :D

bigrebnc1861
February 22, 2010, 08:32 PM
Thanks to all who has responded.

There was a question asked about reloading. I don't reload I may start since what happen last year. I do not wishh to see it happen again. Now I may end up getting both using the whetherby only on certain times and Mainly as a "I have one of those type guns" Something I could pass down to the grand kids.. But the savage would be my main gun to shoot with.

One more thing if I get both I will be missing out on the Ruger GP 100 357 mag. that I have been looking for almost two years. 399.00 it looks like it just out of the box. no scratches on it. I think the guys who sold these guns were hard up for some money with the economy the way it is.

Im looking at
Remington 700 299.00
Savage 111 349.00
Ruger GP 100 399.00

That will almost complete my gun wish list.

uncyboo
February 22, 2010, 09:31 PM
If you look that Remington over real good, and the bore looks OK, you can put that 50 bucks toward your handloading set-up......

Once the initial equipment is bought, the caliber specific stuff isn't too bad. Dies, trim pilots, shell holders, etc.....

bigrebnc1861
February 22, 2010, 09:40 PM
If you look that Remington over real good, and the bore looks OK, you can put that 50 bucks toward your handloading set-up......



Once the initial equipment is bought, the caliber specific stuff isn't too bad. Dies, trim pilots, shell holders, etc.....

I did and the bore looked in real good shape. The reason I believe they are saling it so cheap is that the original owner couldn't offord thwe ammo and needed the money. And the pawn shop that has it, believe it or not are not trying to rob people to make a sale. Do you know of a good handloader?

uncyboo
February 22, 2010, 09:48 PM
Lee Anniversary kit is probably the most economical way to start. RCBS, Hornady, Lyman, any of the major players are OK. I started with the RCBS starter kit many years ago. It's still what I use.

uncyboo
February 23, 2010, 12:59 AM
Uncyboo,here is a link showing what a 300 win mag looks like with the shoulders blown out,thats what mine look like.Hate to doubt the math but seeing is believing.

http://www.larrywillis.com/caution.html

Thanks for the link. That was what I was trying to say. There is almost no neck, and nowhere near 3/8 of an inch, which would be .375.

pwillie
February 23, 2010, 07:19 AM
It all comes down to how much money you want to spend.Weatherby is big money,and then all the rest....No one spoke of a lighter load,like a 150 gr.BST.Great Elk cartridge. I know people who hunt year end and out with a 7MM Mag,hooked up with a 139 gr. Hornady,and take Elk regularly.Flat and fast...Weatherby! Why do you think Weatherbu ammo cost more? Could it be because its the best?

hagar
February 23, 2010, 12:06 PM
I shoot its bigger brother, the 340 Weatherby. Now THAT thing rattles your teeth..:eek:

I actually buy 300 Weatherby brass for it, its exactly the same brass as 340 but necked down, but normally the 300 brass is quite a bit cheaper. Stuff about 90 grains of your favorite powder behind a 250 Sierra, and be prepared to be impressed!;)

U.L.Grant
September 21, 2012, 08:12 AM
QUOTE:
okiefarmer308
Member

Join Date: February 21, 2010
Location: SE Oklahoma
Posts: 20

300 mag short case
My first post here. A couple or 4 years back I was at a gun show and saw one of the prettiest custom stocked rifles ever. The guy said make me an offer,I popped off($200) and was the proud owner of a supposedly 300 win mag built on a 1917 Enfield action. Worse yet it was left handed stock,I can shoot either handed but am primarily right handed. Took it home prepared for mule like kicks. It did not kick as bad as many 30-06's I have shot. It is a very heavy stock,I will admit. After 3 shots I noticed the shoulders looked funny,yep it was stamped 300 win mag but is a 300 Weatherby magnum. It took a couple of trips to an old gunsmith that was sloooooow before it was figured out. Eddystone action so he magnifluxed it to be sure it was safe. My question is,I have a buttload of 300 win mag brass,would it be safe to fire form and just use them? I know the neck would be shorter but would it be feasible? END.


old question but hot topic lately, with the rising cost of 300 Weatherby ammo, and the economy the way it is

yes, if the necks dont' split upon fire forming, and you get a good neck-only resize die from Hornady, you can just resize the necks, reload them to Wby specs, and use them. The neck will just be shorter, that's all. It would help to soften the brass necks for longevity, by annealing them- but that goes for any 300 mag brass, HH Wby or Win Mag- the 300 belted mag family of cartridges is hard on brass to begin with, regardless of specific cartridge chambering.

Norma made a brass headstamped "300 Re Special" that was basically a generic brass 300 mag, with a 300 Win Mag shoulder, but 300 H&H and 300 Weatherby length. It can be fire formed to either 300 H&H or 300 Wby Mag. Or, it can be trimmed and used as 300 Win Mag.

what most don't realize, but is becoming evident now with the advent of the internet and message boards such as this, when you buy a 300 Wby Mag rifle, you really have in effect, a multi-cartridge firearm. It will fire 300 Win Mag, 300 H&H, or 300 Wby mag ammo. The only difference will be, the first 2 smaller magnums, will have slightly less velocity- and once that brass is fire formed to the 300 Wby mag, it will no longer fit in H&H or Win Mag chambers, unless it is resized back again in a full length sizing die.

The 300 Wby Mag will also chamber and fire 308 Norma Mag ammo, but at that point the brass is so short in the neck area, it would be useless for reloading, once fire formed to 300 Wby Mag.

the reason it's not popular to do is, less velocity, and it works the brass more, and less reloads from the brass. Most guys who buy a 300 Wby mag, do so for the ultra-high velocity. And one would look kind of silly loading up their Mark V 300 Wby Mag, from a box of new 300 Win Mag shells from Walmart for $25. So firing 300 Win Mag in a 300 Wby, sort of defeats the purpose.

It would be like putting a Chevy hood ornament, on the hood of a Cadillac. Sure it will bolt on, and it's still a GM, but it's not the right hood ornament.

but to anser your question, yes, you can re-use the Win Mag brass in the Wby Mag, as your findings showed, the neck is still long enough to seat a bullet. Norma knew that when they created the "300 Re special" brass.

U.L.Grant
September 21, 2012, 08:21 AM
QUOTE:

okiefarmer308
Member

Join Date: February 21, 2010
Location: SE Oklahoma
Posts: 20

thanks
Unckyboo(hope I spelled it right).thanks for the opinion. The blown out shoulders leave about 3/8 inch neck to try to seat a bullet, so it would have been a problem with seating. END



exactly, there's plenty of neck left on a 300 Win Mag brass, once fire formed to 300 Wby mag, to seat the bullet- after it is neck sized. Some cartridges only have that much neck, as designed, such as the 300 Savage.

the downside is, now you have 300 Wby mag sized cartridges, with a 300 Win Mag headstamp on them.

and somewhere down the road, someone may try to force-feed that cartridge into a 300 Win Mag. It won't fit, but you can see where this may lead.

it's something you only try for your own personal firearm and use, don't put resized ammo with wrong headstamps into the general circulation, by trading it off or selling it.