Gunsmithing 300 RUM Sendero accuracy question

ALLOUTIND

ALLOUTIND

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Minuteman
Apr 10, 2010
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Livermore Ca
www.billetclamp.com
#1
Kinda new to this reloading thing so bare with me.

I have a Rem 700 sendero 300 ultra mag , I started making loads for it and found a pretty good combo. I was shooting .50 at 100 yrds (5 shot group) also pulled a 1.25 group (5 shot)at 300 yrds. Everything was great.... Well i made a bunch of that same ammo and took the gun to 500yrds. I couldnt get any group better then 6 inches.
I WAS STUMPED!!
So i went home and made another 25 bullets. I went out with my buddy and shot 500yrds again.....
Same results!!
I dont know if it is possible to have a great reload fall apart at 500yrds or ?

The only thing that i changed.....

(After shooting great at 100 and 300.)

I swapped out my stock to see how another felt.I did not shoot the gun with the new one. I just swapped it to check it out. Then i put mine back on to shoot the next day.
im wondering if this could have caused accuracy issues?

Help?
 
#4
Re: 300 RUM Sendero accuracy question

A good load at 100 is not always a good load at 600. A good load at 300 is usally, but not necessarily, a good load at 600. Six inches at 500 is not a disaster: it's a bit more than 1 MOA, which could be simply a poor load plus shooter error - a quite common condition with lightweight magnum rifles.

I assume that the stock has an aluminum bedding block. Do you have a torque wrench? Did you torque the stock screws back to 55 or 65 inch pounds? Did you torque the front screw, then the back screw?
 
#5
Re: 300 RUM Sendero accuracy question

When putting back into the factory stock I very lightly tighten the action screws and then bump the butt on the floor to seat the recoil lug. Then torque up to 55 inch pounds. Reming actually puts a pretty nice barrel on the Sendero. They are pretty smooth out of the box. Try some 210 Bergers with a max charge of Retumbo. Testing a customers rifle last Thursday I shot a couple 5 shot groups rapid fire off a bipod and they all went 1/2 MOA. I would expect better off a mechanical rest.
 
#6
Re: 300 RUM Sendero accuracy question

Shooting a caliber like 3oo rum ultra at 100 yards tells you nothing unless shot over a chrono. Do your research on shooting load ladders. Try doing them at 300 yards. You'll be amazed at what you'll find done this way. As for what to exspect from that caliber.. I know it can do 5", 5 shot groups at 1000. But can you, or that barrel? That is a great long range caliber.
 
#7
Re: 300 RUM Sendero accuracy question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Hired Gun</div><div class="ubbcode-body">When putting back into the factory stock I very lightly tighten the action screws and then bump the butt on the floor to seat the recoil lug. Then torque up to 55 inch pounds. Reming actually puts a pretty nice barrel on the Sendero. They are pretty smooth out of the box. Try some 210 Bergers with a max charge of Retumbo. Testing a customers rifle last Thursday I shot a couple 5 shot groups rapid fire off a bipod and they all went 1/2 MOA. I would expect better off a mechanical rest. </div></div>

+1 on the Retumbo. It pushes 240 SMKs out of my 300 RUM Sendero giving about .5 MOA accuracy. It chronoed around 2730.

My first thought when I read your post was the action screws. Even though that stock comes with an aluminum bedding block, I would still recommend having it bedded.
 
#8
Re: 300 RUM Sendero accuracy question

It sure sounds like a stock related issue. The best way to resolve this question is with carefull range testing i.e. temp, dewpoint, winds, elevation in your optics ect.
 
#9
Re: 300 RUM Sendero accuracy question

168 gr barnes tsx..... everyone is telling me to step it up to 200 gr or so.....

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Baron</div><div class="ubbcode-body">What weight bullets? You need to try 210 Berger VLDs or 210 SMKs!
</div></div>
 
#10
Re: 300 RUM Sendero accuracy question

i have aprox 200 rnds through it....
not ready for a barrel yet...lol


<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Skunkeye</div><div class="ubbcode-body">How many rounds through the barrel? I had a .300 RUM where the groups about tripled in size after 1,200 rds or so. </div></div>
 
#11
Re: 300 RUM Sendero accuracy question

im use to sub moa on all my other guns... it may be the load but im new at the reloading and dont know if this norm. sendero does have aluminum block in stock... i might be bedding it soon. i did get a torque wrench for x-mas so im good there. my bud at the gun shop took it back apart and retorqued it..im taking it out sunday.. we will see im trying some box ammo and another load i had worked up prev.
thanks for the feed back...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Graham</div><div class="ubbcode-body">A good load at 100 is not always a good load at 600. A good load at 300 is usally, but not necessarily, a good load at 600. Six inches at 500 is not a disaster: it's a bit more than 1 MOA, which could be simply a poor load plus shooter error - a quite common condition with lightweight magnum rifles.

I assume that the stock has an aluminum bedding block. Do you have a torque wrench? Did you torque the stock screws back to 55 or 65 inch pounds? Did you torque the front screw, then the back screw? </div></div>
 
#12
Re: 300 RUM Sendero accuracy question

I have never used that method but its sounds great. here is a link to a load ladder. is this how you do it?
http://www.6mmbr.com/laddertest.html
I have a lot to learn.....:(

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Bubb</div><div class="ubbcode-body">Shooting a caliber like 3oo rum ultra at 100 yards tells you nothing unless shot over a chrono. Do your research on shooting load ladders. Try doing them at 300 yards. You'll be amazed at what you'll find done this way. As for what to exspect from that caliber.. I know it can do 5", 5 shot groups at 1000. But can you, or that barrel? That is a great long range caliber. </div></div>
 
#13
Re: 300 RUM Sendero accuracy question

That is a good link for a ladder test. It is definitely the best way to get optimum accuracy.

As far as bullets, If you wanna shoot 168's then get a 308. The 300 RUM is a long range and big game cartridge designed to push the heavy bullets. I wouldn't bother shooting anything lighter than 208/210's. Some guys will use 190's and 200's but the 208 AMAX's or 210 VLD's with their high BC's along with their 3000fps velocities makes them the ideal bullets for the RUM.

If you have a Factory Sendero, then you have the HS stock, it has an Aluminum bedding block. Just skim bed it and shoot the shit out of it.
 
#14
Re: 300 RUM Sendero accuracy question

Alot of people have been telling me to shoot a heavier bullet, I do understand the whole thought behind it.
I told my (ex marine sniper instructor) buddy i wanted to go to the heavier bullet. his reply was there is not enough difference in bc to make a big difference for what i want to do with the gun.
He told me to print up the ballistics on each bullet out to the yardage i want to use it for. so i printed up 4 reports up to 1200 yrds .
i put a barnes 168 gr tsx up against a 200 gr barnes (no lead for california) and the difference was so close it really didnt matter.
I even added a little wind to the mix and the 168gr held it own up to about 1000yrds.
Even at a 1000 yrds in a 10 mph wind it was still acceptable. so im gonna stick with the 168gr for now .. maybe work a bigger gr later for target shooting out to farther distance...
thanks for the feedback.
 
#15
Re: 300 RUM Sendero accuracy question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ALLOUTIND</div><div class="ubbcode-body">Alot of people have been telling me to shoot a heavier bullet, I do understand the whole thought behind it.</div></div>

If you will take note, most of the suggestions have been 208 Amax/210 Berger. Why? Because they work. We know they work becasue we shoot them. A lot. 1/2 the wind to 1200 yds of your 168. If you're watching trace the difference is quite startling. The 208/210's shoot like a laser.

But most also missed your lead-free requirement. The 200 TSX is a pig, so you're right. Pick one that meets your accuracy or energy needs and shoot it.

John
 
#16
Re: 300 RUM Sendero accuracy question

Not much difference????????? My calculator shows a small difference. You are right the Barnes heavies are pretty weak. Please post your ballistic comparison at 1000 yards. Compare Barnes bullets to a 210 Berger at 1000 yards starting out at 3100 fps. Since you are lead free the next best thing is going to be the 180 grain Nosler E-Tip with a .523 bc. Those should easily be launched at 3350fps. Another thing to consider is Barnes bullets have a minimum impact velocity window of reliable expansion. I have heard somewhere around 1800 fps.

 
#19
Re: 300 RUM Sendero accuracy question

I agree with the above. If a bullet isnt going fast enough, beyond 500 will give you a sign without a chrono. I dont have a chrono yet, but I get good consistent shots out to 700+.
 
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