7mm/300 Weatherby

[Burmman]

I bought a Rem 700 from a friend's wife. He had just passed away. So looking at the gun it has no markings on the barrel. She thought it was a 7 STW. Before casting it I did also but the bolt wouldn't close on the STW. What we have figured from a chamber casting it is a 7mm/300 Weatherby Mag. The my friend also has a 6.5x300 wby for sale. So I guess the 7mmx300 wby would make sense also. I looked online to see if I could find some info on this cartridge and couldn't find much info. Does anyone here shoot it ? I would like to know more about it.

 

[Steveb]

I had one years ago before the 7mmSTW came out. After it did, I found that the published loads were the same as mine for the same velocity. One other interesting thing with mine is that it shot the 150 and 175 Nosler Partitions to the same POA at 200 meters. Fantastic long range sheep cartridge!!

Steve

 

[Burmman]

Thanks Steveb. You don't happen to have any brass or loaded ammo laying around ? If anyone has some brass or loaded ammo I would like to confirm that this is indeed what it is. From the casting it looks and measures up but I would just like to know for sure before buying dies and such.

 

[bheadboy]

R W HArt of nescopeck pa, has 30 hart and 7 hart that are based on the Wtby case, check them for brass and info

Bob

 

[glo]

I would expect you wouldn't even have to measure it. If it has the double radius shoulders and is magnum length (2.825”), it's a 7mm x 300 WM. I don't remember any other non-Weatherby wildcats that has the double radius shoulder, but I could be wrong.

MidwayUSA offers 7mm x 300 WM brass http://www.midwayusa.com/product/283926/quality-cartridge-reloading-brass-7mm-300-weatherby-magnum-box-of-20.

Remember this is a wildcat even if the above brass is commercially drawn. Check the neck thickness with a bullet seated and case length to the casting. Most reamer maker will grind the reamer at the neck about .016” over max case length for safety. Also the chamber casting should be about .002” min. over the seated bullet in the case at the neck; .004” over would be better.

Also, get a set of headspace gauges. (Go and No-Go) Any .300 H&H type will do ( .300 WM, .300 Win Mag. 7mm STW etc...). They all headspace on the belt. I if the Go gauge goes and the No-Go gauge doesn't, then you have a .300 H&H Grandchild or .375 H&H Great Grandchild.

If the headspace, case length and loaded neck diameter is good and if the brass chambers, then the cartridge will safely fire. Even if you get the wrong reloading die and set the shoulders back on the brass so the cartridge will chamber, it will safely fire. This is because the cartridge headspaces on the belt not the shoulders.

Finally, if you are reasonably sure it is a 7mm x 300 WM get the barrel stamped or do it yourself.

 

[dennisinaz]

I helped a friend put one together this year, he had Mike Bryant chamber it for him. We are having great luck with Retumbo and 180 Bergers. R25 is decent too. We are crowding 3200 with the 180s.

 

[GNERGY]

I have had my 7mm/300Wby for a long time. I would just neck down Remington 300Wby brass and after the second firing anneal the necks. I also use a 7mm wby fl. sizer die and adjust it higher in the press so I only resize a 1/4 inch of the neck so I don't have to resize the whole case.
My rifle had a 28 inch Hart Stainless bull bbl. I built it for long range grounghog hunting back in Ohio where I used to live. I have been playing with some moly coated 140 gr. Nosler ballistic tips with 86 gr. Imr 7828 SSC with fed mag primers loaded to 3.825 OAL. They average 3560 fps. It shoots under 2 inches at 500 meters. One of these days I'll load up some Bergers and see what it will do at longer distances.
If you have any more questions fire away.
Tarey

 

[drags]

Howard Wolfe invented the 7/300wby (570-996-0449) give him a call and he can fill you in. He has built several 7/300's for us and they are very good guns. My longest kill is 850 yds. on a whitetail with a 168 gr. SMK, we do not use bullets lighter than 162 gr. in the 7/300, the lighter bullets are said to be harder on barrels, I don't know but we don't use the lighter bullets for that reason.
Drags

 

[dennisinaz]

Howard Wolfe invented the 7/300wby (570-996-0449) give him a call and he can fill you in. He has built several 7/300's for us and they are very good guns. My longest kill is 850 yds. on a whitetail with a 168 gr. SMK, we do not use bullets lighter than 162 gr. in the 7/300, the lighter bullets are said to be harder on barrels, I don't know but we don't use the lighter bullets for that reason.
Drags

I have found just the opposite to be true with most calibers. This is one of the main reasons why the 6.5-284 has such a bad reputation as a barrel burner; all anyone shoots in competition is the 140 grain variety.


As for using Remington 300 Wby brass- unless they have completely revamped their brass, it has always been pure junk to me (in 300 WBY). I have built a number of 300 Wbys and have tried every type of brass that I could get my hands on. I had the best luck with the PMC bulk brass and Wby brand/Norma were also quite good. The Remington stuff was not worth loading; off center flash holes, .003+ variance in wall thickness and a high percentage of culls in a lot. I haven't tried it in the past 7-8 years so my experience is somewhat dated but I wouldn't try it again.

We are using WBY brand brass and it is pretty consistent and uniform. No complaints about the brass quality.

 

[sritz05]

Lots of great info for sure any thoughts on who to re-chamber a Vanguard into a 7x300 I have sitting collecting dust.

 

[kendoka66]

I have a thread open also on the 7x300 Weatherby . I had one in 1980s and loved it, The only powder back then was H870 and it gave good velocity and accuracy with the 160 Nosler PT. Mv was 3350. I have posted some new loads on it. So check it out.

 

[kendoka66]

I have a Remington 700LR that I had re chambered to the 7x300 Weatherby.
Since I had one back in the 80,s I thought I would try it out with new powders and the new long range bullets that are available now. I think The 168 ,175 and 180 are the best to use. Us869 and 50BMG,Retumbo all work well so far in my testing. I listed some loads on my thread so check them out.
I have been using 300 weatherby brass in Norma and Nosler they weigh about the same. I one pass through through the F.L. die is all that is needed.

 

[savagedasher]

Ackley and Mashburn was very popular wildcat year back Larry

 

[Hans Gruber]

I would expect you wouldn't even have to measure it. If it has the double radius shoulders and is magnum length (2.825”), it's a 7mm x 300 WM. I don't remember any other non-Weatherby wildcats that has the double radius shoulder, but I could be wrong.

MidwayUSA offers 7mm x 300 WM brass http://www.midwayusa.com/product/28...ding-brass-7mm-300-weatherby-magnum-box-of-20.

Remember this is a wildcat even if the above brass is commercially drawn. Check the neck thickness with a bullet seated and case length to the casting. Most reamer maker will grind the reamer at the neck about .016” over max case length for safety. Also the chamber casting should be about .002” min. over the seated bullet in the case at the neck; .004” over would be better.

Also, get a set of headspace gauges. (Go and No-Go) Any .300 H&H type will do ( .300 WM, .300 Win Mag. 7mm STW etc...). They all headspace on the belt. I if the Go gauge goes and the No-Go gauge doesn't, then you have a .300 H&H Grandchild or .375 H&H Great Grandchild.

If the headspace, case length and loaded neck diameter is good and if the brass chambers, then the cartridge will safely fire. Even if you get the wrong reloading die and set the shoulders back on the brass so the cartridge will chamber, it will safely fire. This is because the cartridge headspaces on the belt not the shoulders.

Finally, if you are reasonably sure it is a 7mm x 300 WM get the barrel stamped or do it yourself.

I have a similar issue. I thought my Enfield was chambered 7stw, but action wouldn't close. Inspected the cast vs the nosler 7mm stw round and the shoulder is at a different length. Went to the ammo shop to investigate rounds and believe the 300 wby mag to be close, except my cast doesn't have a rounded shoulder. Thoughts?

 

[rickiesrevenge]

I have a similar issue. I thought my Enfield was chambered 7stw, but action wouldn't close. Inspected the cast vs the nosler 7mm stw round and the shoulder is at a different length. Went to the ammo shop to investigate rounds and believe the 300 wby mag to be close, except my cast doesn't have a rounded shoulder. Thoughts?

Its a wildcat so... it could be anything. The reamer grinders will make whatever your heart desires.

Aaron

 

[tgoss]

I bought a Rem 700 from a friend's wife. He had just passed away. So looking at the gun it has no markings on the barrel. She thought it was a 7 STW. Before casting it I did also but the bolt wouldn't close on the STW. What we have figured from a chamber casting it is a 7mm/300 Weatherby Mag. The my friend also has a 6.5x300 wby for sale. So I guess the 7mmx300 wby would make sense also. I looked online to see if I could find some info on this cartridge and couldn't find much info. Does anyone here shoot it ? I would like to know more about it.

I have

 

[tgoss]

I have

I have one built in mid 70's by C.C. Johnson in Bakersfield. Ca. Pre-64 Model 70 26" Hart 1:9. Shoots 168 Barnes LRX avg. .275-.325 5 shots w/80 gr. Reloader 25 Fed 215. 3275fps. Only complaint cases don't last.