This will be my last response in regards to barrel length. I think you need to do some more reading. Longer barrel length is good for everything from the 204R to the 6.5 Creedmoor and even more important in overbore cartridges. I could not care less what you think. The facts are the facts barrel length affects speed. The only reason I responded is for newer readers. The newer powders you are referring to actually exaggerate this topic. The slower the powder the more you can use(providing you have the case capacity) and the more velocity you can achieve and the longer barrel will help even more. Yes more powder needs more room to be used thus the benefit from the longer barrel. If this were not the case, if only pressure mattered I suspect we would all just be running the 6br case in our favorite caliber at max pressure. Bryan Litz has done a few barrel cut tests which are a great read. Rifleshooter.com has done quite a few. When you prove physics wrong let me know. I will be building an 16" 30 br throated for 215 Bergers and killing things 2miles away. In the mean time can we please get this back on topic?
Anyone own a 7mm 300 Win Mag?
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This will be my last response in regards to barrel length. I think you need to do some more reading. Longer barrel length is good for everything from the 204R to the 6.5 Creedmoor and even more important in overbore cartridges. I could not care less what you think. The facts are the facts barrel length affects speed. The only reason I responded is for newer readers. The newer powders you are referring to actually exaggerate this topic. The slower the powder the more you can use(providing you have the case capacity) and the more velocity you can achieve and the longer barrel will help even more. Yes more powder needs more room to be used thus the benefit from the longer barrel. If this were not the case, if only pressure mattered I suspect we would all just be running the 6br case in our favorite caliber at max pressure. Bryan Litz has done a few barrel cut tests which are a great read. Rifleshooter.com has done quite a few. When you prove physics wrong let me know. I will be building an 16" 30 br throated for 215 Bergers and killing things 2miles away. In the mean time can we please get this back on topic?
Are you using the 180 hybrids for hunting?
I'm just starting to work up loads for a new Fierce Edge 28 Nosler, and have some 180 HVLDs on hand. Looking for options....
Yes. Either will be fine.
Hello. I'm new to the site and found it while looking for some basic info on the 7mm-300 Win Mag cartridge.
I just acquired a very nice looking custom K98 chambered in this caliber. Actually, I got it by accident, as it was at an estate auction and I read the description too quickly and didn't realize until after I'd submitted my bid that it wasn't 7mm. After I realized the actual caliber and how little info there is out there on it, I hoped to be outbid, but no one else bid, so I ended up getting it for the low starting bid, so at least that's a good start. It has a 26" heavy target barrel marked P.O. Ackley. No dies, brass or anything ammo-related came with it.
From reading some of this thread (it's a LONG thread), I gather that 168 or 180 grain VLDs are a good choice for bullets. When I take possession of it, I'll have to measure the twist rate on it.
For brass, to neck down some 300 Win Mag brass, I see 3 ways - get a CH4D neck die for that caliber, a Lee collet neck die in 300 WM with a 7mm collet, or a Redding bushing neck die in 300 WM with a 7mm bushing and perhaps an intermediary bushing, too. How are you guys making your brass?
Thanks,
Brian
I just acquired a very nice looking custom K98 chambered in this caliber. Actually, I got it by accident, as it was at an estate auction and I read the description too quickly and didn't realize until after I'd submitted my bid that it wasn't 7mm. After I realized the actual caliber and how little info there is out there on it, I hoped to be outbid, but no one else bid, so I ended up getting it for the low starting bid, so at least that's a good start. It has a 26" heavy target barrel marked P.O. Ackley. No dies, brass or anything ammo-related came with it.
From reading some of this thread (it's a LONG thread), I gather that 168 or 180 grain VLDs are a good choice for bullets. When I take possession of it, I'll have to measure the twist rate on it.
For brass, to neck down some 300 Win Mag brass, I see 3 ways - get a CH4D neck die for that caliber, a Lee collet neck die in 300 WM with a 7mm collet, or a Redding bushing neck die in 300 WM with a 7mm bushing and perhaps an intermediary bushing, too. How are you guys making your brass?
Thanks,
Brian
yobuck
Well-Known Member
You will probably find that some of the die makers like RCBS for example make a set for that cartridge.
They do for the 7x300 Weatherby which I've owned for many years.
Just run the 300 case through the sizing die and that's it,
your all done.
You could use a standard 300 Win die for the case body, then any 7 mm die just for the neck also if you happen to have those laying around.
For a hunting gun it's advisable to full legnth size the cases.
Check EBay, you just might find a set listed.
They do for the 7x300 Weatherby which I've owned for many years.
Just run the 300 case through the sizing die and that's it,
your all done.
You could use a standard 300 Win die for the case body, then any 7 mm die just for the neck also if you happen to have those laying around.
For a hunting gun it's advisable to full legnth size the cases.
Check EBay, you just might find a set listed.
Overkill338
Well-Known Member
I wonder if it has an Ackley shoulder. I like the idea of the caliber, I like the unique things. Power wise I guess it should be in between a 7mm RM and an STW. Congrats!
smack
Well-Known Member
I shoot a 7mm-.300 Win Mag Improved. I had CH4D make me a set of custom dies.
Weaselthis
Well-Known Member
Congratulations on the purchase, Brian. I hope the miscalculation turns into a happy find for you! Not too many folks have a rifle w/ P.O. Ackley stamped on the barrel!
Your post struck me and I thought if it were me, meaning I'd be somewhat hesitant to pull the trigger before I found out for sure, but I think I'd have a chamber cast made.
Could this barrel be an improved version of the 7-300WM perhaps? If so, I would want to be sure and seat the bullet out far enough and be conservative on the powder charge to insure that the bolt face was flush to the case head for the first loading to get it fire formed to the 40 degree shoulder if that was indeed the case.
Hope the rifle does well for you.
Take care.
Kiwi Nate
Well-Known Member
Hi Brian, on your unknown, I suggest you start with a Hornady 7mm Mag neck die. this differs to the regular Hornady 7mm neck die. The 7mm Mag neck die has both body and shoulder clearance to cope with a range of case styles. Its not the most ideal die for match level concentric ammo but it is the correct die for this task.
Once you have the die (or die set), you can tentatively set about necking down a few .300 WM cases. size the necks down until the case fits snuggly in the chamber of the rifle. Do not simply try to wind the die down to the shell holder as this die is designed for shorter cases like the 7mm WSM. Perform this task incrementally until the case fits the chamber.
Following this, I suggest you fireform using Trail Boss Powder. this will ensure that you are able to form a case without any risk to yourself. 28 grain TB behind a 160-162gr bullet will produce about 1700fps.
Once you have fire formed cases, you can try sizing a case again. Ideally, the case should then be run over a concentricity gauge such as a Sinclair, just to see how much distortion occurs within the case. If the die (and seating) works for you, producing concentric ammo, you can carry on with it. If not, you will most likely now need to move on to another brand of die. However, you must take stock of the fact that the Redding for example, only partially sizes the neck of the .300 WM. If your case has a 40 degree shoulder, you will end up sizing even less of the neck after fitting a 7mm bushing to the .300 die.
It is important to understand what dimensions you are dealing with first before going too much further ahead. A cerafide cast would be ideal but this is the modern internet / forum world where folk are just as likely to say thanks for the advice and then do nothing about it. The Hornady die is the easiest way for you to get into this.
Once you have the die (or die set), you can tentatively set about necking down a few .300 WM cases. size the necks down until the case fits snuggly in the chamber of the rifle. Do not simply try to wind the die down to the shell holder as this die is designed for shorter cases like the 7mm WSM. Perform this task incrementally until the case fits the chamber.
Following this, I suggest you fireform using Trail Boss Powder. this will ensure that you are able to form a case without any risk to yourself. 28 grain TB behind a 160-162gr bullet will produce about 1700fps.
Once you have fire formed cases, you can try sizing a case again. Ideally, the case should then be run over a concentricity gauge such as a Sinclair, just to see how much distortion occurs within the case. If the die (and seating) works for you, producing concentric ammo, you can carry on with it. If not, you will most likely now need to move on to another brand of die. However, you must take stock of the fact that the Redding for example, only partially sizes the neck of the .300 WM. If your case has a 40 degree shoulder, you will end up sizing even less of the neck after fitting a 7mm bushing to the .300 die.
It is important to understand what dimensions you are dealing with first before going too much further ahead. A cerafide cast would be ideal but this is the modern internet / forum world where folk are just as likely to say thanks for the advice and then do nothing about it. The Hornady die is the easiest way for you to get into this.
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Thanks for the tips. When I get my hands on the rifle next week, I'll cast the chamber first, just so I know what I'm dealing with.
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Overkill338
Well-Known Member
That's exactly what I was saying. With Ackley stamped on the barrel, I'd expect it to have an Ackley shoulder.
Weaselthis
Well-Known Member
Brian, that is a SWEET looking rifle.
Congrats.
Hope is shoots as good as it looks.
Take care.
Congrats.
Hope is shoots as good as it looks.
Take care.
Overkill338
Well-Known Member
@Broz I accidentally ran across this post, and seen where I was estimating velocities for you in 2010. How did things turn out with the rifle?
KIWI NATE: Back on pages 5 & 6 of this thread, you posted a link to your article on your 7mm Practical. The link is bad now. Do you have a current link to that article?
