Morning Gentlemen >> I have myself a Remington Sendero that is/was chambered for the .300 RUM. My intentions, with getting this rifle, were to turn it into 1000 - 1500 yd. (+) varminter. The factory 26" barrel was sold, as my plans always included a 30" Lilja. I'd like to have this gun built around the LRB 162 gr. J40. However, if that bullet doesn't pan out, the 1:9 twist recommended for it would still work well if I planned switch to the 162 gr. A-Max, 168 gr. VLD, 168 gr. MatchKing or 180 gr. VLD. After talking with Lilja, plans for the barrel included 30", 1:9 twist, 4-groove, #7 contour (similar to factory barrel) and fluted. Am I on the right track here?
Now, the big question I find myself getting stuck on is with cartridge selection. I had wanted this rifle chambered in either the 7mm RUM or 7.21 Firebird, to get some speed behind those high BC bullets in that .284 class. Barrel life really isn't a huge concern for me as this rifle will "not" see extended shooting sessions on a daily basis. We tend to take several rifles with us on a hunt and spread things out pretty well between them so that over-heating isn't allowed to happen. The guns are well maintained. Recoil concerns would be addressed with adding weight to the gun stock and a muzzle brake, if necessary.
Does this all sound like a reasonable thing to consider trying? I've seen my brother work with his 6mm-284 at extended ranges and while it works great, I've seen how the wind can affect those 100 +/- gr. .243 bullets and was looking to lessen this by using the 160 - 180 gr. .284's. Am I missing something? Any other cartridges that I should be considering that would work in this Sendero platform? I have considered the short magnum stuff but think I would rather have something with a tad more powder capacity.
The closer that I get to the finished product, I'll be back with questions about optics, but fear that I've already bored to many with all these questions. Any opinions and/or tips would be appreciated. Thanks for your time. >> klallen
After having several of the larger and smaller 7mm calibers in various barrel lengths, I can give you my opinion, for what it's worth.
Out of the two you mentioned, I would stick with the 7mm RUM Mag. or add to that, the straight 7MM mag as a consideration. The straight 7mm Mag will give you Less barrel wear and throat erosion.
Good brass is available for the straight 7 MM Mag but, not the 7mm RUM and you don't have to fool around and do a lot of fireforming of the cases. Load it and shoot it after picking the powder and bullet combination that works best.
I have a straight 7mm mag with a 30" barrel and it shoots very well. If you want to load it hot, you can stay with a 7/300 Weatherby with the right powder. The 7/300 Weatherby and the 7mm RUM are very close in ballistics.
I have proved that the straight 7mm Mag, with the correct powder will turn up 3200 to 3250 FPS with 162 gr and 168 gr bullets in a 30" barrel to some of my friends who said it couldn't be done and also own 7/300 Weatherby mags.
We matched them up side by side over the chronagraph.
I use 168 gr MK and 162 Gr Hornady Match and A-Max bullets in mine, exclusivly. The same bullets are used in my 7/300 Weatherby.
There are some very good bullets up to 180 gr available with high BCs and if you run out of reloads, factory ammo can be found everywhere. I have some custom bullets that are 176 gr and 186 Gr but, not available any longer.
If you like the 7mm bore and for your application, the 7mm Mag would be the way I would go especially with the 30" barrel you plan on installing. Necking down the 300 RUM case to a 7mm makes for a very inefficient case. That compares (almost) to a 378 Weatherby case being necked down to a 7mm.
We necked down a 378 case to 7mm and 6.5 long ago and found they were VERY inefficient in BOTH bore diameters.
Had to use a lot more powder to equal what a 7/300 or 6.5/300 Weatherby would give with the SAME bullet weights for each.
1000 to 1500 yards is NOT out of the question for the 7mm Mag, especially for ground hogs and whitetail deer plus the fact of longer barrel wear and case availability and quality.
The trick for the 7mm Mag is to have your smith chamber it so you can seat the bullets further out (not Weatherby Freebore) in the neck before touching the lands, to allow for the use of as much powder as possible.
Good luck to you.
PS---You might want to consider a brake for it also. I find that you can shoot a medium to heavy recoil rifle MUCH more accurately with a brake installed. Some match shooters put brakes on the 6.5/284 too.
as an add on here---If you don't want to overwork the straight 7mm Mag Brass to maintain a higher velocity, I would go with the 7/300 Weatherby Mag over the 7MM RUM.
I'm currently working on a 7mmRUM project myself. As Darryl stated, it IS overbore, 'inefficient', & a general pain to reload for.
With that being said, it is also: super flat, super fast, moderately recoiling, & very very wind resistant. From a 30" barrel, 156s (BC of .640) are going @3,550 & 180 class bullets (BC @ .740-.750) from 3,300-3,400 at safe pressures. They retain velocity well for the distances you describe. Still looking for the most accurate & consistent load though.
If you'd like, I can E-mail some loads & comments to you that take up quite a bit too much space for the forum....
I have a 34 inch Lilja tube in 7mm STW. Mine will not shoot 162 gr bullets in any other than VLD/J40 bullets. You are partially correct about the 1:9 twist. However that is only good for VLD style bullets and the 162 gr Hornadys do not have the length as the LRB do or a VLD style such as the Berger 180gr vld's. The length/twist ratio plays a big part in the reason the VLD's and LRB's stabalize, shorter bullets just will not work with mine. The Bergers are quite a bit shorter than the LRB 162gr and I suppose the weight helps with getting it stabalized. Maybe you've had some success with shorter 162gr, but for me it wants 180 or higher or longer.
Since we basically have the same barrel cept for 4 inches yours should perform very close to mine. My barrel is a 4 groove what is yours?
Mine will shoot the Berger 180gr very well but anything else with that twist ratio will not shoot in mine and ive been through a lot of 7mm bullets and I have a lot left over that will just not shoot period. 6 different powder loads I cant even tell you how many different bullets ive tried from 140 up to 175 gr. Anything but Bergers and LRB will give me shotgun grouped size patterns at 100 yards. I am currently pushing the Bergers out of my 7mm STW at 3100 fps behind 74.5 grs of H1000.
At those velocities, you probably won't find the consistant, accurate loads your looking for.
If you dropped back 150 to 200 FPS, you might just find it.
That's the problem with most calibers and especially overbore calibers. The speed kills accuracy in them too.
I can drive the 7/300 Weatherby faster at the expense of downrange accuracy. At 3250 FPS with the 168 MK it works real well.
The straight 7mm Mag will get to that speed when using H4831 and 168 Gr MK also. That was a favorite loading for the 7mm Mags at Williamsport, years ago.
The 7/300 Weatherby shoots real well with 87 gr of H870 or WC 872 and the 168 Gr Sierra MK
Thank you all!!! Lots of stuff to think about here and a few more questions raised.
Mr. Cassel, you mentioned that there was a bit of a problem getting "good" brass for the 7mm RUM. Could you please explain further? I've been using Remington brass with my STW for a while now and found it to be of good quality (holding up to high pressure repeated loads). Can I not expect the same from Remington made 7mm RUM brass? Also, you mention the inefficiency of the 7mm RUM. That really doesn't concern me as much as having an accurate finished product. Can the RUM be made to shoot accruate at 1000 yds. and beyond with its increased velocities? Seems as though you're saying the lower velocities of a 7mm RemMag, while lacking the trajectory of the RUM, would increase the accuracy potential with the heavy bullets at 3250 - 3300 fps being the sweet spot, so to speak. Am I reading you correctly? As kind of a after thought, I have my 7mm STW that has only been thought of in the past as my big game rifle. Would it not give me the same results as say the 7mm/300 WbyMag you talked about? DAVEOSOK (thanks for your STW experiences) seems to be doing very will with his. With all the brass I have for this cartridge, is this an avenue that needs to be looked into? A long range varminter chambered for the 7mm STW so that the heavier bullets can be seated long? I suppose it's all a moved point if that 3250 fps is actually the perfect velocity and reachable with the 7mm RemMag. Seems like I'm going in circles here ;o) . I just want to get this right and appreciate the assistence. Thanks for letting me draw form your experience.
SPEEDBUMP, I'd love to hear about your RUM experiences. You can reach me at firstname.lastname@example.org at your convenience. Looking for all info I can get in putting this thing together. The velocity / to accuracy relationship mentioned above has got me a bit confused / concerned. I'm wondering if you are experiencing this in your own reload findings ???? I've heard of many a long range varminter succeeding with .257 STW's and .257 Banshee's in 30" barrels. These are their babies and we're talking heavier .257 bullets (100 gr.) at 4000 fps +/- and still getting all the accuracy they want and results they demand at 1000 - 1500 yds. Seems as though these things would be far more overbore then what the 7mm RUM or even Lazzeroni's 7.21 Firebird would be in same length barrels. Boy, I've got a lot to maul over here. Good thing I've got a great place like this to get ideas from. Chat with ya'll later. >> klallen
The problems with the Remington brass are many. For 1000 yard match shooting, it is a flop in any caliber that I have heard talk about and used myself.
You must weigh and mic 100 cases to get 10 that match in most cases, especially in the RUM cases. I have the 300 RUM IMP Tomahawk and wish I could get any brass other then Remington. The brass is very soft and simply does not hold up well in match shooting. The brass flows more and primer pockets expand more in Remington brass.
Hence, the potential for real good accuracy is not there.
As per the 7mm mag, 7/300 Weatherby -either of the two would be my choice over the 7 RUM, if only from the brass stand point. It is badly overbore and with a 4" shorter barrel expect 100 to 140 FPS less then the other poster stated.
I think you stated you wanted a 30" barrel. That in itself would warrent using cases no bigger then the 7mm Mag, 7STW or 7/300 Weatherby. Any bigger case and the barrel would not be long enough to burn some of the slower powders completely.
These are all suggestions but, keep in mind, if your after REAL GOOD accuracy, I don't think you will find it with Remington brass and the 7 RUM at full max power loads at 1000 yards.
That's what the other poster is experiancing now. He may end up loading down (in volumn) to equal a smaller case size to get that accuracy. Out of 227 shooters in two classes at Williamsport, I believe there are 3 or 4 still using the 7mm bore and not doing real good with it as per consistancy.
At speeds of 3150 to 3250 (168 gr MK) you may just find the accuracy level your looking for. When you say accurate, I think of shooting small groups at 1000 yards.
The 7/300 Weatherby and the 7mm Mag (loaded up) may just be the velocity range for good accuracy. The 7/300 Weatherby held the record at Williamsport for a short time, 20 years ago. The 7mm Mag won some aggs back then also.
"Top notch" accuracy is found with good brass plus lower velocities in just about any caliber.
Norma and Lapua brass seems to be tops.
Good luck to you.
Darryl Cassel [img]images/icons/smile.gif[/img]