help with 300 mag

[popwarlick]

shooting a 300 win mag sen.It has been accurized.Im shooting 180gr. accubond,75.5gr.re22,fed.primers,lapua brass.I am putting the bullet to factory OAL.6x24 burris black diamond w/target knobs.I cant get the groups out of it that i think the gun is capable of.What is a good group at 400 yds.Any advice on a different load or anything will sure help. thanks Terry

 

[tscott]

If I were you I would try both the 168 and 180 Berger VLD. My 300 Win Mag shoots the 168 the best with Ramshot Magnum. I've had great luck with Berger on game and paper.
Good Luck,
Tim

 

[geargrinder]

Your OAL. Are you loading to the book OAL? Or to the max OAL your magazine will fit?

I'll also tell you that bergers shoot great. My 300 likes 190's with 81-82g of H1000.

 

[mikebob]

Try changing your seating depth, when I shot 180 AB they liked to be around .010 off the lands. In almost all my guns they shot best groups for me around .010 - .015 off lands.

 

[squirrelduster]

My brother has a Sendoro and I have a Hart both in 300 win mag. My best groups are at 74.5 gr. RE22 with the 180 accubond and my brother is at 74.8 gr.
Try backing your powder charge down and see what happens.

 

[trueblue]

popwarlick,
To answer the other part of your question, a good group @ 400yds would be 3" or less.

 

[mikebob]

I was looking through my old load data and 75.5 rl22 was my brother and I same load, mine was .010 off lands his was .020 off lands. Both guns shot around 1.5" groups @ 300 yards. I dont have coal as they were measured with stoney point gauge but i think it was somewhere around 3.55 - 3.6. That was about 1/2 gr off max load if I remember right so be careful if loading any higher. Most guns shoot better if the bullets are seated closer to the lands than factory coal. I would start at .010 0ff and work your way out a few thousands at a time and i bet you find a sweet spot. AB are good bullets.

 

[johnnyk]

popwarlick,
Is this a sporter weight barrel and are you letting it cool in between shots? Also, did you work up this load in your rifle or just pick it from the manual? What kind of groups are you expecting? Four inch groups @ 400yds would be MOA, anything less would be gravy. That factory OAL probably isn't helping much. I haven't shot the AccuBonds out of my .300WM yet, but I do shoot the Ballistic Tips and I run them .010" off the LaG's. The AB and NBT's have the same tangent ogive. JohnnyK.

 

[LONGSHOOTER]

I have a 300 WM Sendero SF, about 10 years old. The factory rifles seem to come with SAMMI maximum chambers, with generous neck diameter, and long freebore. I find for mine to be accurate, I must fireform brass, then partial neck size only, and then seat rather long, but not fully as long as the magazine. I use a max charge of IMR 4350 behind a Nosler 165g or 180g BT with a cartridge overall length of 3.525", which is 0.020" off the lands. Mine groups 1/2" at 100. The magazine can take a cartridge of 3.600", which if you seat this long, you might be well into the lands, which could create excessive pressure. I think the biggest key for the factory barrel, is partial neck sizing, which helps to align the bullet with the bore, which helps to increase accuracy, and then of course, finding the right load.

The 300 WM can be quite versatile. I also load 110g Speer spire points, at 1800-2200 fps for small game and close varmints, and 3600 fps as fast movers. These loads, even tho' having a big jump to the rifling, are quite accurate.

hope this has been helpful,
longshooter

 

[popwarlick]

Thanks for the info,goingto get out there this weekend and trywhat yall said TERRY

 

[Michael Eichele]

While there are things you can do to help your accuracy using the components you have, you also need to keep in mind that a given rifle may or may not respond well to the components you put in it. To find her real potential, you may need to try different powders and bullets. Try the 180 AB's with another powder or 2 even. Then try the 200 AB's with the same 2 or 3 powders ect......H1000 is a tough one to beat. Also RL19 shouldnt be overlooked, especially with the 180's in a win mag.

Also have you checked the runout on your cases? (crooked necks)

 

[popwarlick]

I havent checked the runout.Thats 1 tool i aint got.What load do u shoot with the 1000.Iv e never turned the necks,checked the runout but i guess i need to start.How much does that affect accuracy.I talked with Sierra tech. and he said he shot a 190gr. matchking,even for hunting.Itsure has a better bc.What do yall think. TERRY

 

[Michael Eichele]

I have used the 190 SMK for hunting quite a bit and was more than satisfied with the inflight ballistics and always less than satisfied with it on game. I stopped using it for hunting altogether for big game.

Run out can cause a fair amount of trouble. how much it affects accuracy depends on how much RO there is. It doesnt work as good as a guage but if you roll them on a flat smooth surface you can see it with the naked eye if there is alot of it.

What kind of 400 yard accuracy are you getting?

 

[popwarlick]

Im shooting about a 5in. group