a good load for 300 ultramag

BLooDTRaCKeR · Mar 12, 2013

I've got a rem. 300 ultramag sendero, 26" barrel. I'm tired of shooting factory loads through it. I would like to see the guns true potential especially after missing a 6x6 bull elk at 236 yards with a dead rest only to find out that my factory loads were all different lengths afterwards. So I am getting into reloading this year to create the perfect load and see what my gun really "eats".

Anybody have this gun? and if so, what have you found to work best for powder type/bullets? I have studied a few books and have plenty of powders to choose from as well as bullets suggested. However, I would really like to hear what some of you RUM owners are using as a gage for my starting point before I go and dump a bunch of money into bullets and powder.

PS, I know that what works for your gun may not work for mine, but I would like feedback for a starting point.

Thanks in advance.

sageadvice · Mar 12, 2013

The old "blame it on the Factory Load" trick! lol

Good luck! Several guys here got it down with the 300UM, i'm sure you'll get some good help!

Joey

"It's all about knowing what your firearms practical limitations are and combining that with your own personal limitations!"

beech18 · Mar 12, 2013

RL-25 90 Gr
Barnes Triple Shock 168 Gr

RL-25 88 Gr
Barnes Triple Shock 180 Gr

Those shoot good for me.

Cahunter805 · Mar 12, 2013

200gr accubond and retumbo or h1000 is where id start.

Browningbar23 · Mar 13, 2013

215 berger Hybrid or 210 berger vld
93.5 gr Retumbo
Federal 215

freebird63 · Mar 13, 2013

I had good results with 180gr hornady SST's with retumbo powder and 215M primers. H1000 is a good powder.
180gr Barnes TTSX are also a good choice.

Chuck in Boise

mtmuley · Mar 13, 2013

If I were you (I've been shooting and hunting with a .300 RUM for 13 years) I'd start with the 200 grain Accubond and RL-25 and Retumbo. Between those two powders, you should be able to find an accurate load in the 3100 to 3200 fps velocity range in your 26 inch barreled rifle. With the case capacity of the RUM, I'd bypass 180 gr or smaller bullets. I use Remington brass and Federal 215 primers. (Remington was the only brass 13 years ago, and I've never had a problem) Keep an eye out for the new Nosler Accubond LR. As far as Bergers, if you think you will never have a close range shot, have at it. Otherwise expect a mess. mtmuley

brdhuntr · Mar 13, 2013

Mt Muley is right on, the bigger the better,especially for long range, i too load Remington brass,and can't wait to try the new Nosler ABLR bulletts!!

lip_curl · Mar 13, 2013

210 berger vlds and retumbo...should group out to at least 800.

sandbagger · Mar 13, 2013

+1 on what mtnmuley said. Retumbo and 200 gr Accubonds are what I would start with. This combo shoots sub MOA out of my factory barreled M70.

BLooDTRaCKeR · Mar 14, 2013

Guys,
I appreciate all the feedback. It is all very good information. I already have the Retumbo powder, My dad has some 180 grain boat tails, I felt like I needed to go a little heavier so I'm glad some of you mentioned the 200 and 210 grain.

I do have one other question for you "edjumacated" gun owners.

After a powder and bullet is chosen, how critical is the measurement between the bullet and the lands once the shell is chambered? I have heard of people going into the lands a few thousanths and people backing off of the lands a few thousanths.

I know bottom line is "the shell has to fit in the magazine". The reason I ask is because a buddy of mine clued me in on my factory ammo being ALL different lengths and I'm not talking about thousanths of an inch either. There is one bullet that has a difference of 1/8" OAL!

How critical is this measurement? Should the bullet infact be touching the lands when fully chambered or should it be slightly off the lands? Is OAL one of those variables you play with along with grains of powder/bullet selection?

Thanks.

Cahunter805 · Mar 14, 2013

Making sure the bullets are all the same length is important for consistency. With your factory RUM you probably wont be able to get close to the lands and will be limited to mag length. 3.650 is where I would start or whatever length cycles in your mag.

greyghost · Mar 14, 2013

I own the same rifle as you. I use 88g of H4831 with 180g Barns TSX or 180g Nosler AB. Those two bullets shoot identical as one another in my gun @ 3300 fps with under .5" MOA at 100 yards. My OAL is set to the max length my magazine will allow.

sandbagger · Mar 14, 2013

Starting around 3.600" is a good place to start if this is the max length of your magazine. At this stage I would forget about worrying about the perfect OAL and focus mainly on finding the right powder charge. To find the right powder charge you'll want to do a ladder test, looking for your rifles sweet spot. Watch for your groups to shrink and open up; when the groups shrink you know your "in the neighborhood". Start fine tuning the powder charge around the powder weight that shoots best. Consistency in your reloading and shooting is key.

ishootaRUM300 · Mar 17, 2013

You asked about seating. If I understand you right you are asking if you should load the in to the lands i.e. so you are pushing the unfired bullet into the rifling. You do not want to do this you will cause a spike in pressure and you could have a huge problem i.e. wrecking your gun