Reloading the BIG 7mm's (RUM or STW), just curious.

[jtoews80]

I've been wondering for a little while how the 7mm RUM is to load for. I've know it's freebored 0.4" from Remington, so does this round have some interesting load characteristics??? I've only used the 7RM not the bigger STW or RUM, so my curiousity has been caught. I've wanted a 7mm Sendero in STW or RUM for awhile, but can't quite justify it with the 264 in the safe. A 28-31" barrel would do crazy things with either caliber, but I'm wondering if I've missed something. I know there is a curious lack of data for the RUM(Nosler #6 only listed 3 powders) & Sierra doesn't offer data at all, so I'm curious as to why. It is a seriously overbored round, but heck so are the 264 wm, the weatherby's, STW's, 22-250 & 220 Swift. Any one have a 7mm RUM and load for it??? I know there are a few STW guys on here and those are supposed to shoot well, what loads work in the STW??

CC

 

[FOTIS]

Retumbo is the powder for the Rum. I have had 3 or 4 of them, and I can tell you that the 160 is the bullet of choice. Launch it at 3300 fps and you're done.

 

[big rifle man]

jtoews, I've been shooting a 7STW for some time and found that either RL22 or IMR7828 works well with 160 grain bullets. I had a match 28 inch barrel installed on a 700 action and am able to get 2 1/2 inch groups at 300 yards when I do my part. I've shot 140 grain handloads using 7828 and have gotten 3475FPs through my chronograph. The 7STW is a speedster but needs a long barrel. I haven't pushed for max velocity and feel I don't more.

 

[jtoews80]

What had gotten me thinking about the big 7's was:

I had ordered a 270 wby for my wife, she put up a fuss about not needing it, so I had to change the order to a model 700 XCR 338 RUM. Meanwhile, she will still want to claim my 30-378 :? for deer hunting.

Initially, I was going to build a mauser 6.5mm RM or 264 with a palma barrel, but the costs of doing that equal a new rifle's price on an a 60 year-old action or more.

If I start with a savage action and decide on a production chambering like a STW or RUM I wouldn't need custom dies, reamers, etc. Nor would I need any gunsmithing done besides checking headspace. I'm not saying the build is on, just that it could be fun and not bad for price.

AS Always, thinking, but not building yet :evil:


CC

 

[wingnut]

I've been wondering for a little while how the 7mm RUM is to load for. I've know it's freebored 0.4" from Remington, so does this round have some interesting load characteristics??? I've only used the 7RM not the bigger STW or RUM, so my curiousity has been caught. I've wanted a 7mm Sendero in STW or RUM for awhile, but can't quite justify it with the 264 in the safe. A 28-31" barrel would do crazy things with either caliber, but I'm wondering if I've missed something. I know there is a curious lack of data for the RUM(Nosler #6 only listed 3 powders) & Sierra doesn't offer data at all, so I'm curious as to why. It is a seriously overbored round, but heck so are the 264 wm, the weatherby's, STW's, 22-250 & 220 Swift. Any one have a 7mm RUM and load for it??? I know there are a few STW guys on here and those are supposed to shoot well, what loads work in the STW??

CC

Supposedly, Nosler did not include the 7mm RUM in their #5 because they could not get realiable/consistant pressures. Might have been that they were trying powders that were too fast. Seems they worked it out for #6.

To get a good comparision between the 7mm STW and the 7mm RUM, take a look at the Hodgdon data. However, they don't seem to give a barrel lenght: http://data.hodgdon.com/main_menu.asp

If I were to do a 7mm RUM:

It would have a barrel lenght of 32 inches to take advantage of a slow powder.

I would load it with at least 175g bullets to, again, take advantage of a slow powder. Remember, this is a magnum's magnum.

I would load it with a slow powder that filled the case to at least 95%, perferably 100%. Overbore has nothing to do with it. Its how slow the powder is. See:

http://www.24hourcampfire.com/ubbthread ... #Post87621

YMMV.

Edited to change 34 inches to 32

 

[Richracer1]

To get a good comparision between the 7mm STW and the 7mm RUM, take a look at the Hodgdon data. However, they don't seem to give a barrel lenght: http://data.hodgdon.com/main_menu.asp.

Per Hodgdon's 2006 Annual Manual:

7MM RUM - 24" Barrel and 1:9.5" twist

7MM STW - 24" Barrel and 1: 10" twist

 

[Antelope_Sniper]

Wingnut has some good things to say.
I've been shooting the 7mm STW for over 10 years now with jaw dropping results. My rifle from the factory had a 26" barrel, and after 2700+ rounds, I put a new 30" tube on it.
My standard load launches a 160gr AB at 3475.
Last time out I broke 3700 with 150 BT.

Looking at the commercial loading books, you might think I'm crazy (ok the 3700 is a little spicy, and will not be a standard load), but as wingnut suggested, the secret is barrel length, and sloooooooow powders. Almost all the of the canister powder is really too fast for the 7mm stw/untra mags. In order to exploit the true cababilities of this rifle you need Military suprluss powders, WC872 (20mm powder) WC860 (50 cal powder) and WC868 (new surpluss powder, perhaps used in both). With 95+ grains of a hard starting ball powder, you will also need a HOT primer. Think Fed 215, and Fed 215gm. I don't think it matters much, they both work well, but very little else does when it come to these powders in these rifles.


So there it is. Great cartridge when used with a long barrel, slow powder, and a hot primer.

 

[boomer68]

I just picked up a 7mm STW, and am thinking of trying the 160gr AB. What would be a good powder to try first? Mine is a Ruger #1.

 

[jtoews80]

Anybody use US 869 in these 7mm's?? It is a 20mm powder and is availible up here in Canada. I've never tried it because Retumbo always posted higher velocities in the rounds I load, but it is very slow.

CC

 

[wingnut]

Anybody use US 869 in these 7mm's?? It is a 20mm powder and is availible up here in Canada. I've never tried it because Retumbo always posted higher velocities in the rounds I load, but it is very slow.

CC

From Hodgdon (I suspect 24 inch barrel, too short!)

7mm STW-

160 GR. SFT SP Hodgdon US 869 .284" 3.565" 85.0 2922 46,400 CUP 90.0 3041 50,800 CUP
160 GR. SFT SP Hodgdon H50BMG .284" 3.565" 88.0 2929 46,100 CUP 90.0C 2970 46,600 CUP
160 GR. SFT SP Hodgdon H5010 .284" 3.565" 84.0 2762 41,600 CUP 86.0C 2877 45,700 CUP
160 GR. SFT SP Hodgdon Retumbo .284" 3.565" 75.0 2909 46,700 CUP 80.2 3056 53,600 CUP
160 GR. SFT SP Hodgdon H1000 .284" 3.565" 76.0 2930 44,300 CUP 80.7 3084 51,500 CUP
160 GR. SFT SP IMR IMR 7828 .284" 3.565" 72.5 2900 48,400 CUP 77.0 3085 54,200 CUP
160 GR. SFT SP Winchester Supreme 780 .284" 3.565" 69.0 2838 45,800 CUP 73.0 2976 51,500 CUP
160 GR. SFT SP Hodgdon H4831 .284" 3.565" 70.0 2884 45,900 CUP 74.0 3037 52,300 CUP
160 GR. SFT SP Hodgdon Hybrid 100V .284" 3.565" 64.0 2850 46,300 CUP 69.0 3013 52,500 CUP
160 GR. SFT SP IMR IMR 4831 .284" 3.565" 65.0 2730 41,600 CUP 69.5 2926 51,800 CUP
175 GR. NOS PART Hodgdon US 869 .284" 3.585" 84.0 2908 50,100 CUP 88.0 3020 53,200 CUP
175 GR. NOS PART Hodgdon H5010 .284" 3.585" 81.0 2758 44,300 CUP 85.0C 2921 51,600 CUP
175 GR. NOS PART Hodgdon H50BMG .284" 3.585" 85.0 2851 46,900 CUP 89.0C 2973 52,300 CUP
175 GR. NOS PART Hodgdon Retumbo .284" 3.585" 72.0 2819 48,300 CUP 77.0 2967 54,200 CUP

7mm RUM-

160 GR. NOS PART Hodgdon US 869 .284" 3.600" 97.0 2928 50,400 PSI 103.0 3192 62,900 PSI
160 GR. NOS PART Hodgdon H50BMG .284" 3.600" 94.0 2985 55,600 PSI 100.0 3144 63,400 PSI
160 GR. NOS PART Hodgdon Retumbo .284" 3.600" 88.0 3003 53,700 PSI 94.0 3212 62,800 PSI
160 GR. NOS PART Hodgdon H1000 .284" 3.600" 85.0 3007 56,500 PSI 91.0 3167 63,500 PSI
160 GR. NOS PART IMR IMR 7828 .284" 3.600" 84.5 3140 62,000 PSI
160 GR. NOS PART IMR IMR 4831 .284" 3.600" 76.5 3050 61,000 PSI
162 GR. HDY SPBT Hodgdon US 869 .284" 3.650" 100.5 3075 58,700 PSI 103.5 3173 62,800 PSI
162 GR. HDY SPBT Hodgdon H50BMG .284" 3.650" 94.0 2979 56,000 PSI 100.0 3119 62,600 PSI
162 GR. HDY SPBT Hodgdon Retumbo .284" 3.650" 89.0 3009 53,100 PSI 95.0 3223 62,700 PSI
162 GR. HDY SPBT Hodgdon H1000 .284" 3.650" 84.0 2993 55,600 PSI 89.0 3127 62,500 PSI
168 GR. SIE HPBT Hodgdon US 869 .284" 3.650" 96.0 2899 53,100 PSI 101.5 3089 61,900 PSI
168 GR. SIE HPBT Hodgdon H50BMG .284" 3.650" 94.0 2942 55,600 PSI 100.0 3118 63,400 PSI
168 GR. SIE HPBT Hodgdon Retumbo .284" 3.650" 89.0 2986 54,400 PSI 94.0 3171 63,300 PSI
168 GR. SIE HPBT Hodgdon H1000 .284" 3.650" 85.0 2988 57,500 PSI 90.0 3116 63,500 PSI
175 GR. SFT SP Hodgdon US 869 .284" 3.600" 95.0 2851 51,800 PSI 102.0 3077 63,000 PSI

 

[Antelope_Sniper]

Here's a good powder source:

http://www.patsreloading.com/patsrel/prices.htm

 

[jtoews80]

I went to a gun sale & show in Red Deer today. Drove 4 1/2 hrs to find that there was little to no reloading supplies there and that most of the merchants there had upped the prices or were just heniously overpriced to start with their store prices.
I was 30 seconds to late on a NIB 8mm Rem Mag for $650 CaD. I kept looking and found a Browning A-bolt synthetic in 7mm STW for $550 CaD, which is cheap. I haven't seen an A bolt magnum in a years since they are 1100 new.

I checked the barrel and it looks alright(a little throat wear), Registration card says new in november 2005 and the bluing wear on the reciever looks like minimal wear. There is alot of bluing wear on the barrel, but supposedly that is from scabbard use on a saddle. So, now I've got to determine if the barrel will last this year and if not get a new tube on the way so I can use it this season. There has been a few adjustments made to the mag, so that may have caused problems, but I'll have to wait on dies, brass and more days off to load up a few and get back with a range report.

CC

 

[jtoews80]

HAHAhahaa, ok, they're 720 new. Not that great of a deal, but try and find a 7mm STW or RUM. either they aren't around or I wasn't seeing them.

CC

 

[boomer68]

Welcome to the STW club!
I am just waiting for brass and dies to arrive for mine, and will start some load development.
Glad to see another Albertan

 

[Antelope_Sniper]

Glad to hear you found one. Welcome to the club.
I Imagine you will really like that Browning.
After a range test, let me know if you need a recommendation on a barrel maker.

 

[jtoews80]

Tried the browning 7mmSTW at the range on the 100 yd line. Started with a bore sighted 3.5X10 VXIII Leupold scope. 6 inch groups at best with Fedral Premium 160 grn Gamekings.

There is a slight mark in the blueing on the barrel from the forearm so it could be a stock issue, but more likely a bad chambering job when it was turned into a STW from the original Rem Mag.

I missed the target completely with 3 or 4 rounds. I will remount the scope and make sure nothing worked loose, make sure the windage adjustment is as close to center as possible and bore site it with the rear mount screws. And try to make sure the stock isn't rubbing. The bore is clean and looks almost new, so that isn't the problem. I may have the local smith check headspace too. I'll try measuring a couple cases too to see if they stretched any amount.

I haven't made it out to buy dies and brass yet, so I may try opening up the chamber to 7mm RUM to save the barrel or just putting a new tube on it. A longer barrel won't hurt the ballistics at all and a little more weight may make it more fun to shoot off the bench. These shotgun patterns really frustrate a shooter.

CC

 

[jtoews80]

Upon further inspection of the barrel clearance on my 7 stw I found a couple tight spots where the pinch was serious enough to wear the blue down to shiny steel. I did notice that the recoil lug has been glass beded as well, so this rifle has had accuracy issues before this. Be a sweet deal if I can make it shoot.

CC

 

[Antelope_Sniper]

Sorry to hear about the shotgun patterns, but as you suggested, freefloat that barrel first. Just an interesting note, my STW DID NOT LIKE Sierra Matchkings. I haven't tried them again since I rebarreled it. If I was zeroed with noslers, they would hit the paper at 50 years, and grouped about 2 1/2 feet at 25 yards. So, I would freefloat, and try some balistic tips.

 

[Guest]

Also of note, Browning actually started glass bedding the lug at the factory several years ago, so yours may be one of those, and not as bad as you think.

 

[jtoews80]

I did a little research, something that I should have done prior to buying a rechambered rifle.

The Browning A-bolt 7mm Rem Mag has a factory 1-9.5" twist, this was a Rem Mag reamed out to STW. I will try loading 120, 140 & 150 grain bullets to see if the lighter bullets stabilize better. I'll remount the scope before I proceed, but time will tell if I have to rebarrel.

CC