A RUM question

[Cowboyblaster]

Im relatively new to building long range rifle's. The 7mm remington ultra mag im working on now being my second. Im working with remington 700 actions because I know them to be excellent. My question though is this.
When a 7mm 168gr berger bullet has to be pushed furthe into the case neck than desired to be held in the magazine how can you load this case with say a 190gr or furthermore how can this action accept a 300 Rum shooting a 200+ grain bullet. I do realize that is a larger diameter bullet but only by 2 thou and a long action is what it is. The way it looks to me is if i wanted to use 180 gr bullets in my 7mm i would have to operate the rifle as a single shot . I know im probably wrong about this so please if you have the time and knowledge please educate me . Thank you

 

[adam32+P]

Wyatt's extended mag box.

 

[MagnumManiac]

I am in the same boat with my Rem 700's in 7STW and 300RUM.
I am new to both, but not new to building full size magnums on 700 actions.
As adam32+P states, the fix is a Wyatt's, but you must understand this requires fitting. The bottom of the action must be milled for it to fit. The 3.850" box would probably accomodate the longest bullets for the 7RUM.
This is what I am in the process of doing, getting parts has been a major hurdle for me.

Cheers.

 

[AZShooter]

I feel there is too much emphasis on worrying about a longer bullet impinging on powder space. Get the cartridge to fit and feed from the magazine regardless of bullet's seated depth in the case. There might be a tiny loss of velocity in some situations. It is not a big deal.

I posted a pic many years ago on this site where I seated a 230 gr Berger in a 300 WSM to fit and feed from a 2.8" mag box on my friend's Browning A bolt. Even with this long bullet buried into the case it still got 2735 fps in a 22" barrel! We joked that the bullet's base was sitting on the flash hole. My late friend Don shot his last elk with that combination and at 300 yds it flattened that cow elk!

As stated by previous poster, the modification can be done to your Rem's mag box via the Wyatt's mag box for a longer OAL. I did that to my 300 RUM in a post 64 model 70.

To further enhance accuracy capabilities a custom reamer can help. You decide the jump to the lands, throat angle, chamber neck dimension etc. Personally I own 15 reamers which were spec'ed out for my needs. IMO only way to go.

In my experience most bullets can be made to shoot accurately without them kissing the lands. The notable exception is a Berger VLD. They can be finicky. Berger suggests four seating depths which are quite far apart to see how your rifle will respond. While true that a VLD will generally shoot well close or into the lands, they can be made to shoot with a significant jump too. It can be a pita but it can be done.

A easier solution is not using VLDs but if you must use a Berger then use one of their hybrid designs. They tend to shoot well with just about any jump to the lands.

 

[Shane Lindsey]

Wyatt's extended mag box.

Be sure to buy the 4". Not the 3.85". Gives you a little more wiggle room to play with seating depths.

As mentioned by AZShooter the powder capacity I have recently found going from single loading to mag feed in a Wyatt's and an Accurate mag for a chassis was negligible. I ran them up single feed and came back to the shorter length due to accuracy. If it would have gained me 100 FPS, I may continue to look, but it did not.

I still like the option to seat long, IF the rifle likes it. In this case with the 245 Berger and the 215 in a 300 RUM it prefers them with a good bit of jump. Not as sexy looking, but accuracy was best there.

 

[Cowboyblaster]

Thank you this is the experienced knowledge i was looking for and yes for me it's all about the accuracy as i hope to make somewhat of a name so that i can sell these very capable rifles as something you can pack for a week and shoot a goat at 1200 yards with a single shot . Weve already chronoed the loads to 3240 to 3262 out of ten rounds fired very slowly. 1/2 hour between shots all were in this spread. And accuracy apears to be very good. 168gr berger VLD . Personaly id prefer a partition but im not building the 7RUM for methanks very much for your input

 

[cape cove]

There are several cartridges that are handicapped by short throats and short magazines. I have a 300 RUM and this is the case and my 300 Win mag is certainly in the same boat espically with heavy bullets ( 200 gr +)

 

[MagnumManiac]

There are several cartridges that are handicapped by short throats and short magazines. I have a 300 RUM and this is the case and my 300 Win mag is certainly in the same boat espically with heavy bullets ( 200 gr +)

Interesting, not one of my 7 300WM have short throats. I have both SAAMI and A191 chambers. The SAAMI throats run .220" or thereabouts and the A191 runs .245".
These are not short throats.
In fact, the 300WM SAAMI chamber is hindered in standard length actions because you can only load to 3.390" in their magazines and it takes 3.620" to get to the rifling with most VLD or hybrid bullets. If you want closer, then you single feed or buy a Wyatt's.
My new 300RUM does have a short throat in comparison. It is a Rem 700, and maybe that is why it's designed that way taking in regard to the 3.7" length of their mag box.

Cheers.

 

[cape cove]

My 300 Win is a BSA Cf2. The mag restricts me to an OAL of 3.413 and with the 200 gr Barnes LRX single loading I'm limited to 3.570 because of the throating. With this OAL there is a lot of case capacity taken up by the bullet and even worse if it is to fit the mag.

 

[Cowboyblaster]

I feel there is too much emphasis on worrying about a longer bullet impinging on powder space. Get the cartridge to fit and feed from the magazine regardless of bullet's seated depth in the case. There might be a tiny loss of velocity in some situations. It is not a big deal.

I posted a pic many years ago on this site where I seated a 230 gr Berger in a 300 WSM to fit and feed from a 2.8" mag box on my friend's Browning A bolt. Even with this long bullet buried into the case it still got 2735 fps in a 22" barrel! We joked that the bullet's base was sitting on the flash hole. My late friend Don shot his last elk with that combination and at 300 yds it flattened that cow elk!

As stated by previous poster, the modification can be done to your Rem's mag box via the Wyatt's mag box for a longer OAL. I did that to my 300 RUM in a post 64 model 70.

To further enhance accuracy capabilities a custom reamer can help. You decide the jump to the lands, throat angle, chamber neck dimension etc. Personally I own 15 reamers which were spec'ed out for my needs. IMO only way to go.

In my experience most bullets can be made to shoot accurately without them kissing the lands. The notable exception is a Berger VLD. They can be finicky. Berger suggests four seating depths which are quite far apart to see how your rifle will respond. While true that a VLD will generally shoot well close or into the lands, they can be made to shoot with a significant jump too. It can be a pita but it can be done.

A easier solution is not using VLDs but if you must use a Berger then use one of their hybrid designs. They tend to shoot well with just about any jump to the lands.

My best man will agree with everything you are saying here i think and he's my reload guy but he loves those bergers and I dont i realize they are very accurate but i dont like the way they act inside an animal . My wife would agree with me in that she'd rather not bite into shrapnel But as far as the seat depth im glad to hear its ok to sink them a bit we still got 97.5gr of h1000 in there and not even close to a compressed load in that big case

 

[Earnhardt]

My best man will agree with everything you are saying here i think and he's my reload guy but he loves those bergers and I dont i realize they are very accurate but i dont like the way they act inside an animal . My wife would agree with me in that she'd rather not bite into shrapnel But as far as the seat depth im glad to hear its ok to sink them a bit we still got 97.5gr of h1000 in there and not even close to a compressed load in that big case

Cowboyblaster, is this load for a 7MM RUM?
Is your load of 97.5 grains of H1000
168 grain Berger
What is the length of your loaded cartridge?
Thanks

 

[Cowboyblaster]

My best man will agree with everything you are saying here i think and he's my reload guy but he loves those bergers and I dont i realize they are very accurate but i dont like the way they act inside an animal . My wife would agree with me in that she'd rather not bite into shrapnel But as far as the seat depth im glad to hear its ok to sink them a bit we still got 97.5gr of h1000 in there and not even close to a compressed load in that big case

Cowboyblaster, is this load for a 7MM RUM?
Is your load of 97.5 grains of H1000
168 grain Berger
What is the length of your loaded cartridge?
Thanks

Yes yes and yes and soon as the wife wakes up ill mic those loads for you haha

 

[Cowboyblaster]

My best man will agree with everything you are saying here i think and he's my reload guy but he loves those bergers and I dont i realize they are very accurate but i dont like the way they act inside an animal . My wife would agree with me in that she'd rather not bite into shrapnel But as far as the seat depth im glad to hear its ok to sink them a bit we still got 97.5gr of h1000 in there and not even close to a compressed load in that big case

Cowboyblaster, is this load for a 7MM RUM?
Is your load of 97.5 grains of H1000
168 grain Berger
What is the length of your loaded cartridge?
Thanks

Yes yes and yes and soon as the wife wakes up ill mic those loads for you hah

Yes yes and yes and soon as the wife wakes up ill mic those loads for you haha

Oh and its a 26" barrel with 1 in 9.25 twist

 

[Earnhardt]

I have one word of advice for you,

STOP!!!

STOP shooting that load immediately!!!

Quick loads says, that load that you're shooting in your 7 MM ultra mag, has 93,500 psi

The maximum pressure for a 7 MM ultra mag is approximately 64,000 psi

so you are approximately 50% over maximum

I am literally surprised that that gun has not blown up when your wife was shooting it

STOP Shooting that load immediately!!!