Hi! Looking at the .338-06 amazing effectivness and ability to work well with fast powders and short barrel I just thought it must be a way to do this with a 7mm. Im thinking of necking up a 6 or 6,5 caliber to 7mm and get velocitys around 2800-2900 with 140-160 grain bullets using a 20-22 inch barrel. Im so tired of all overbore 7mm calibers there must be a way to do a effective 7mm?
Searching for a effective 7mm
- Thread starter TheSwede
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In the 30-06 length cartridge you have the 280 rem which is a 30-06 neck to accept 7mm bullets been around a long time for some reason it never caught on well, however many custom hunting rifles have been built on this cartridge along with a slew of factory offerings which are still available. Then we have the 7mm-08, I have had two rifles chambered for this cartridge an outstanding cartridge with a 308 win parent case being necked to accept 7mm bullets.. this makes an ideal short action hunting rifle while nipping at the heals or mirroring many long action cartridge ballistics/performance. 284 win, 7rsaum, 7 rem mag (maybe most popular) 7wsm(had a win feather weight very nice combo) as you can see 7mm has a loyal following you can find lots more info google 7mm cartridges.
I almost forgot what started it all the 7x57 Mauser which is comparable to the 7mm-08 only in a long action... I would never ever hesitate to pick up a nice rifle in 7x57 which has been around since 1892...seems they knew what they were doing as to the case capacity etc...this is a outstanding cartridge.
I almost forgot what started it all the 7x57 Mauser which is comparable to the 7mm-08 only in a long action... I would never ever hesitate to pick up a nice rifle in 7x57 which has been around since 1892...seems they knew what they were doing as to the case capacity etc...this is a outstanding cartridge.
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ironworkerwill
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I agree on post #2 AND 3. OP I believe you are describing either 7x57 or 7mm08. The 7mm08 is a true short action cartridge and operates at a little higher pressure than the slightly longer 7X57. The ballistics are virtually identical for both. If a hand loader was to match the 7x57 to the 7-08 pressure then I'm sure 100fps gain would not be out of the question. The 7x57 will be better at pushing heavier bullets due to its larger case capacity.
Well, if you want that kind of velocity with those weights of bullets, what's wrong with being "overbore?" The cartridge is either more overbore or longer. The gas is all going out a 7mm tube, either way. Shorter and fatter just happens to be more accurate than longer and skinnier.
Post is kind of confusing. You have necked up the 30-06 to .338 to make it more efficient with faster powders and a shorter barrel. Yeah, you could "neck up" a 6.5mm, but most of the cartridges are necked down from their parent case, and in many of them there is already a 7mm version. And if you want to use faster powders and shorter barrels, you aren't going to get those kinds of velocities with those weights of bullets. The 7mm 150 grain bullets is kinda long, not something you're gonna get to 2900 fps with a fast powder or a small cartridge.
Fast powder and short barrel in 7mm is talking like 7mm TCU and 7mm Waters. Gonna get maybe 2000-2300 fps.
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Ok i might been off regarding velocitys but what I ment was a 7mm caliber using fast powder. There are tons of nice 7mm caliber. 280 remington is my favourite! But all of them 280/284/7-08/7x57/7x64 work best with 24 inch or longer barrels and with slow powders.
I was looking at how good the .223 cartridge handles 6mm bullets (6x45 or 6tcu) also how great the .30-06 handles .338 when necked up. I just thought there must be something for the 7mm. Maybe necking up the 6,5x55 or the 6,5x47 lapua?
I was looking at how good the .223 cartridge handles 6mm bullets (6x45 or 6tcu) also how great the .30-06 handles .338 when necked up. I just thought there must be something for the 7mm. Maybe necking up the 6,5x55 or the 6,5x47 lapua?
You are trying to have your cake and eat it too. 0.338 is bigger than 30 cal. 7mm is smaller. The only way you're going to use a similarly fast powder is by using lighter bullets with similar sectional density. Maybe 100-120 grain bullets. And/or using a smaller case. 7mm TCU, or whatnot.
If you want the same velocities with the same weight bullets, you can use any shape case you want, and it won't make a difference. You will still need just as slow a powder! The 160 grain 7mm bullets have a high BC, high SD. There's only so much you can do to get those pills up to speed.
CarJunkieLS1
Member
OP you pretty much described the 7mm-08. I have a custom 7mm-08 w/ a 23" barrel it shoots a 140gr bullet at 2870fps. I'm using a stiff charge of Varget seated out at 2.860" and it still feeds from my magazine.
As far as necking up or down you can take .243 and neck up or take .308 and neck down. A premium 140gr bullet (partition, ttsx, scirrocco, etc.) will take any game animal in North America.
As far as necking up or down you can take .243 and neck up or take .308 and neck down. A premium 140gr bullet (partition, ttsx, scirrocco, etc.) will take any game animal in North America.
WestKentucky
Member
Lighter 7mm... 7-30 waters 30-30 case necked down and blown out a bit. Gets near but not all the way into your velocity range. I love mine.
Gloob has a point your 30-06 necked to 338 gives you the option of a faster powder burn because of bore size... however using same BC I would bet the 30-06 using similar fast powder would get speeds similar.
Bullet BC makes a difference, not to mention anything over 30 cal will not be very high bc unless specialty bullets. Slow burning powders is not a bad thing, it is the saving grace on most of the cartridges today.. If your just wanting a 200 yard cartridge you might look at a 223 case necked to 7mm stick with light bullets (under 120 gr)... all this said if your wanting around 3000 fps with even 140 gr bullets there is no replacement for displacement, short fat, long tapered, in between does not matter you will be in the same burn category of powders.
Bullet BC makes a difference, not to mention anything over 30 cal will not be very high bc unless specialty bullets. Slow burning powders is not a bad thing, it is the saving grace on most of the cartridges today.. If your just wanting a 200 yard cartridge you might look at a 223 case necked to 7mm stick with light bullets (under 120 gr)... all this said if your wanting around 3000 fps with even 140 gr bullets there is no replacement for displacement, short fat, long tapered, in between does not matter you will be in the same burn category of powders.
Yes I've been way out with 140-160 bullets 
been reading alot now and there is no way, just like you said Gloob. I guess 7mm-08 is the nearest I will come. Found some interesting data on 7-30 waters ackey improved is a neat round but I want to take deer/elk sized game so I need alittle bit more power. Im still keen on finding load data on necking up 6xc/6,5x55/6,5x47L cases. I think they could perform well with bullets up to 140 grain. 6,5x55 should handle 140-160 grain pretty well dont you think?
been reading alot now and there is no way, just like you said Gloob. I guess 7mm-08 is the nearest I will come. Found some interesting data on 7-30 waters ackey improved is a neat round but I want to take deer/elk sized game so I need alittle bit more power. Im still keen on finding load data on necking up 6xc/6,5x55/6,5x47L cases. I think they could perform well with bullets up to 140 grain. 6,5x55 should handle 140-160 grain pretty well dont you think?Jim Watson
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How would a necked up 6.5x55 be any better with "fast powders" than the standard 7x57 already recommended? If a 7x30 Waters Improved is too small for you, there is not much in between. Even if you designed a wildcat to fall in that very narrow gap, it would be hard to tell a difference.
CarJunkieLS1
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If you are thinking the 7mm-08 is the closest thing to what you want...which is a fine choice BTW. And you are obvioulsly a handloader then how about the 7mm-08AI it offers 75-125fps over the standard 7-08
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