Howa 300 Mag Load Help.

71.0grs of IMR4350 with a 180gr Sierra BT shot well too.This was a 200yd group with those.

Other option is the Howa comes in 300 Weatherbee lol as well. You might be able to get the parts to allow a 300 Bee magazine follower and box to facilitate longer loads fitting in the rifle. Just an option

Try some of these if you wanna spend a little moola on some premium bullets.

https://cuttingedgebullets.com/308-180gr-rifle-maximus-50ct

Start loading at 78.0 gr. H1000 and work up from there.

The mono metal bullets like Barnes typically like a good deal of jump. Hammer bullets are advertised as being fairly jump insensitive.

I'd load what you have closer to the lands and single feed them before I handicapped accuracy. No guarantees that closer is better, but you need to try it.

Rechamber to 300 prc?

Have you shot some Hornady 300wm précision hunters in that howa? Just to establish a base of what is potential.

D-mon said:

Rechamber to 300 prc?

Have you shot some Hornady 300wm précision hunters in that howa? Just to establish a base of what is potential.

Click to expand...

No I have not. Federal GMM 190gr were the top of the line ammo I have shot and it was like 1.75MOA with those

Let me give you a couple of first steps to consider.

Have you tried factory match loads 4 groups of 5 at 100 yards. What is your average group size? What is your variation?

Do you have any hints of scope failure like flyers that you cannot call or difficulty making adjustments? You should be about to dial 1" left and move your group exactly 1" left.

What is your twist rate? What bullets have you tried? Have you tried Berger or Hornady? Specifically 180gr to 200gr.

Have you tuned your fl die to deliver consistent CBTD measurement and bolt close force?

With a given bullet, have you shot the full range of load data for given components?

Personally, I pick my bullet by use and twist rate.

Then I load 25 rounds at CBTO=lands-0.030" and vary the charge into 5 even groupings.

I had a 300 WM that loved 165, 180 and 200 Accubonds. 165 and 180 BTs too.

Shot barrel out and tried same loads as before in my new barrel... no dice!! After fighting through powders, primers, etc finally decided to try a group with some Sierra 180 GK and Prohuntersvwith my old charge of 75 grs of R22. Bingo!! Both shot 3 shot groups right at .500-.600.

Also my OAL with the GK was 3.490 and 3.510 with the Prohunters; both .015-.020 off the lands. That's where I ve most always had good luck with multiple calibers and cup and core Bullets. I ve been loading over 50 years so have some trigger time.

Lastly, both the Sierras fit and function comfortably in my R700 magazine.

Usually most guns will group a number of reasonable burn rate powders well; I ve found bullets to typically be more temperamental in some guns.

Good luck

Wolf76 said:

The mono metal bullets like Barnes typically like a good deal of jump. Hammer bullets are advertised as being fairly jump insensitive.

I'd load what you have closer to the lands and single feed them before I handicapped accuracy. No guarantees that closer is better, but you need to try it.

Click to expand...

nksmfamjp said:

Let me give you a couple of first steps to consider.

Have you tried factory match loads 4 groups of 5 at 100 yards. What is your average group size? What is your variation?

Do you have any hints of scope failure like flyers that you cannot call or difficulty making adjustments? You should be about to dial 1" left and move your group exactly 1" left.

What is your twist rate? What bullets have you tried? Have you tried Berger or Hornady? Specifically 180gr to 200gr.

Have you tuned your fl die to deliver consistent CBTD measurement and bolt close force?

With a given bullet, have you shot the full range of load data for given components?

Personally, I pick my bullet by use and twist rate.

Then I load 25 rounds at CBTO=lands-0.030" and vary the charge into 5 even groupings.

Click to expand...

I think you guys need to re-read the OP. He clearly stated that he has an extremely long throat.

What you two are suggesting is that he convert his rifle to a single loader, cause if he does what you suggest, there is no way the cartridges will fit the magazine.

wonderman4 said:

I think you guys need to re-read the OP. He clearly stated that he has an extremely long throat.

What you two are suggesting is that he convert his rifle to a single loader, cause if he does what you suggest, there is no way the cartridges will fit the magazine.

Click to expand...

I've read the original post and suggested an appropriate response.

You only have 4 choices when you have a long throat and nothing shoots well at mag length.
1) load long and single feed
2) add an extended box mag
3) use bullets that often work well with a big jump (Barnes recommends starting 50 off)
4) set back the barrel to correct the throat
The suggestion to load longer than mag length is to establish if the gun will shoot well at all. If it does, then maybe the mag box extension is the answer or perhaps single feeding it.

After shooting thousands of bullets in Magnum cartridges, most cup and core bullets shoot best from slight jam to .050 off. Many times magazines won't get you within .1"

Most factory rifles are throated long. Trying bullets with a tangent ogive such as a Nosler BT rather than a secant ogive like a VLD bullet reduces the need to seat closer to the land. Bullets like a Sierra Match King give me good results from box mag length seating, or from COAL from reloading manuals. Also some factory barrels will prefer pressure bedding. So you may need to pressure bed the tip of your fore end

nksmfamjp said:

Let me give you a couple of first steps to consider.

Have you tried factory match loads 4 groups of 5 at 100 yards. What is your average group size? What is your variation?

Do you have any hints of scope failure like flyers that you cannot call or difficulty making adjustments? You should be about to dial 1" left and move your group exactly 1" left.

What is your twist rate? What bullets have you tried? Have you tried Berger or Hornady? Specifically 180gr to 200gr.

Have you tuned your fl die to deliver consistent CBTD measurement and bolt close force?

With a given bullet, have you shot the full range of load data for given components?

Personally, I pick my bullet by use and twist rate.

Then I load 25 rounds at CBTO=lands-0.030" and vary the charge into 5 even groupings.

Click to expand...

With the GMM I shot I think 3 groups of 5 the other five shots were used to establish zero. All groups were of similar size but I did not record them for statistical analysis.

I have tried mainly hornady and sierra bullets. 195 gr ELDs and and the 212 gr ELDx for hornady. Sierra I believe I tried some 180gr game king and a 165 gr game king I believe. All were between 1.5-2MOA. I dont have any Berger bullets in my stash as of yet was hoping to find something a little less pricey that had acceptable accuracy.

I have not noticed any scope issues. Scope has tracked very true with all adjustments and I have verified torque on all associated mount screws. The twist on the barrel is 1-10 as well.

I have not done full ladder testing on any bullet yet. Tried 2 loads of H1000 and 2 loads of 7828SSC for the 195 gr ELDs. In the past I try a few middle of the road test loads and find what seems to show signs of working and then ladder test from there. So far haven't found anything that's super impressive as of yet.

Reloading has been using once fired federal brass from this rifle, trimmed to length and only neck sizing.

I think if I believed that seating closer to the lands would help my accuracy I'd just seat them long and shoot to see my rifle would group. That would be easier than modifying the rifle or loads. There could be other issues causing the problem like a poor crown, loose mounts, or loose reticle. Some barrels won't shoot better than 1.5 MOA or worse. When that happens I generally start from scratch and check the whole rifle from scope mounts to action screws first.

JKRamsey1991 said:

With the GMM I shot I think 3 groups of 5 the other five shots were used to establish zero. All groups were of similar size but I did not record them for statistical analysis.

I have tried mainly hornady and sierra bullets. 195 gr ELDs and and the 212 gr ELDx for hornady. Sierra I believe I tried some 180gr game king and a 165 gr game king I believe. All were between 1.5-2MOA. I dont have any Berger bullets in my stash as of yet was hoping to find something a little less pricey that had acceptable accuracy.

I have not noticed any scope issues. Scope has tracked very true with all adjustments and I have verified torque on all associated mount screws. The twist on the barrel is 1-10 as well.

I have not done full ladder testing on any bullet yet. Tried 2 loads of H1000 and 2 loads of 7828SSC for the 195 gr ELDs. In the past I try a few middle of the road test loads and find what seems to show signs of working and then ladder test from there. So far haven't found anything that's super impressive as of yet.

Reloading has been using once fired federal brass from this rifle, trimmed to length and only neck sizing.

Click to expand...

Given all of this new info I think I'd do this. I'd check the crown, or have a trusted smith check it. If that looks okay I'd try a proven scope. If that doesn't change anything I'd try pressure bedding the fore end. That's what I would do because it looks like you've done the work trying different loads. I hope that helps.