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Problems getting a tight group on my 300 Rem. Ultra Mag

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Unread 09-14-2008, 10:25 PM
Junior Member
Join Date: May 2008
Posts: 12
Problems getting a tight group on my 300 Rem. Ultra Mag

I am only shooting about 1 3/4" groups at best at 100 yrds. I've had the gun shecked by Remmington and they say it is within specifications. I have the model 700 SPS. I've tried custom loads and we are still working on them. Other than trying different loads is there anything else I can do to help with accuracy?

Does anyone have a load they would share with me for this exact gun they like and that is accurate? Like out to 400-500 yards? I would like to be shooting 6" groups at this range.

I have shot rifle for years and I have a Remington 700 SPS in the 30-06 and I can shoot 3/4" groups with a factory load at 100 yards. So, I am very comfortable with the Rem. model 700 and very cofident with my 30-06.

The 300 R.U.M. is new and I went through a break-in barrel process (which was then trumped by a lapping process by the company). The gun used to shoot 2 1/2" groups at 100 yards (at best) and then the guys at Remington did do a little work, they recrowned the barral, lapped it and one other thing with the end of the barrel. They shot 1 1/2" in groups (I'm guessing in a lead sled).

Since the work done I have shot three groups of five shells. The worst group was 2 1/2" and the best was 2 1/8" (I kept my paper and just measured it). I had no wild shots...they could have all been coverd by a small circle. The factory loads (before the work was done) were Remington Premier Core-Lokt Ultra bonded 180 gr. bullets, power level III. I also tried the scirocco bullets (Same info. as above). My trigger has also been adjusted to 2.75 lbs.

The loads I shot after the work were hand loads. Rem. casing, Hodgeden powder (92.5 grains seemed to be the best) 208 grain Hornady A-Max bullets (not the best for hunting but great coefficient for accuracy). and Winchester mag. primers. I use a concrete bench with a small adjustable Caldwell rest for the front of the gun and a sandbag in back. I let the barrel cool between shots and I do my best to squeez the trigger and let the shot suprise me. I have a Leoupold Gold Ring 4.5 X 14 power scope on.

I know my groups are not as tight and that could be due to not having a lead sled but even with the factory 1.5" group I'm looking for tighter.

My next step is to have the barrel floated and look at bringing the bullet out further in the casing but I should be tighter at this point in time.

Can anyone help?
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Unread 09-14-2008, 11:49 PM
Platinum Member
Join Date: Jun 2003
Location: Hermiston, Oregon
Posts: 2,030
Re: Problems getting a tight group on my 300 Rem. Ultra Mag

The following loads were all very accurate to 800 and 1150 yards from my Rem 700 LSS 300 RUM. Only thing done to it was trigger job.

92-94g of H1000 with 200g AB or SMK's was 3/4MOA or better out to 800 yards.

88g H1000 with 210g VLD's was also 3/4 MOA

89g H1000 with 220g SMK was also 3/4 MOA

Triggers good, good scope, good rests. I think you just need to work on finding a new load. Try a couple different powders. Most 300 RUMs love H1000 or Retumbo. Load the bullets to the max length of your magazine. In my Rem LSS it was something like 3.660" for the AB's and I loaded the SMK's and VLD's to the lands but used it as a single shot.

Forget about doing 5 shot groups for a factory sporter contour hunting rifle like the 300 RUM. 3 shots is good enough. How many times do you get an animal to stand around for more then 3 shots???

Hope it works out for you. The 300 RUM is capable of very very good accuracy. My personal bests were 1.5" at 525, 3.5" at 800, and about 60-70% hit ratio on a 15" steel plate at 1150.
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Unread 09-15-2008, 12:07 AM
Platinum Member
Join Date: Jan 2004
Location: Blackfoot, Idaho
Posts: 8,876
Re: Problems getting a tight group on my 300 Rem. Ultra Mag

Don't know if these suggestions will help but they can't hurt.

First free float that barrel. Take those two pressure points off flush with the surrounding wood. Seal these later.

Next take 5 one-dollar bills. Stack 'em and grip the ends. Slide them from the down the barrel channel all the way to the recoil lug. They should slide very easily and together.

If they don't remove wood from the appropriate spots.

After this is completed and the rifle is fully assembled, hold the rifle vertically with on hand around the barrel and fore arm gripping firmly the butt is on the bench. With your other hand and proper tool, alternately loosen and tighten both receiver mounting screws. If you feel movement between barrel and stock with the hand holding the gun, have it bedded.

You seem thoro and particular so I'd recommend pillar and skim bedding if bedding is indicated as necessary. For the intended use of the rifle, I'd have it pillar and skim bedded as a matter of course.

Another indication would be if your receiver mounting screws cinch up "all of a sudden" or torque down with several turns. My thoughts are that they should cinch up quite quickly. If they do you a good fit between wood and metal is indicated. If not the action is being squished into the stock which is usually not a good thing.

After the above it would be a myriad of variables to test. Bullets, powder, primer, seating depth, an on and on and on........

If would have been nicer if the groups were stringing in a particular direction. Symmetrical groups that size at 100 yds are a bit worrisome.
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Unread 09-16-2008, 06:30 PM
Junior Member
Join Date: May 2008
Posts: 12
Re: Problems getting a tight group on my 300 Rem. Ultra Mag

Thanks for the input, suggestions, and loads you have tried. I'm getting the gun free floated and glass bedded. It sounds like alluminum pillars are prob. not necessary with the synthetic stock. What are your thoughts on the pillars?

As far as load changes. I will look into different loads. I do use Retumbo powder (I wasn't clear on that before) and I am going to try set the bullets out farther as well.

I'm also putting a vias break on to take some kick out, which will help me be more accurate on the range.

I'll keep an eye on the post in case new info or suggestions come in.

Thanks again and that is where I am at for now. Happy and safe unting everyone.
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Unread 09-16-2008, 09:33 PM
Platinum Member
Join Date: Jan 2003
Location: The rifle range, or archery range or behind the computer in Alaska
Posts: 3,830
Re: Problems getting a tight group on my 300 Rem. Ultra Mag

Also had great success with RL-25 in the 300 RUM.
Long range shooting is a process that ends with a result. Once you start to focus on the result (how bad your last shot was, how big the group is going to be, what your buck will score, what your match score is, what place you are in...) then you loose the capacity to focus on the process.
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Unread 09-17-2008, 04:33 PM
Junior Member
Join Date: May 2008
Posts: 12
Re: Problems getting a tight group on my 300 Rem. Ultra Mag

What is RL-25?
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Unread 09-17-2008, 05:39 PM
Bronze Member
Join Date: Sep 2008
Location: Spokane, Washington
Posts: 76
Re: Problems getting a tight group on my 300 Rem. Ultra Mag

RL-25 is an alliant powder, This is the powder my sendero likes best as well

98 gr behind 168gr Berger, 215m federal primer.
.5" to .75" groups all day

I recently switched to a Barnes bullet and it actually consistently groups tighter than the Berger’s.

My barrel has severe throat erosion and I still get 1" to 1.25" groups @ 100yards
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