300 Norma Improved 35 degree

[Ledd Slinger]

Nice! Looks like a real shooter

I’m waiting on my revised “BD V2” reamer from JGS to arrive so I can complete my third 300 NMI build on a Bat HR. Though I will be using a 10 twist 26” barrel and the 220gr bullets. Should be some good info to add in the database because I know there aren’t many of us that have ran a 10” twist with the NMI. And although a world record 10 shot 10x group was shot at 1K with the 220gr in competition (using a 10 twist barrel) and I had excellent terminal results on big game with them last year, the 220 LRHT still has a ways to go before it can be considered fully proven for consistency.

 

[Bodhisafa]

What is the best reamer for this cartridge? And does any gunsmith have it?

 

[Ledd Slinger]

Alex has his own reamer and matching die sets and it shoots really well. My current rifle uses a design of my own and is also a 35 degree shoulder but differs from Alex’s design in a few aspects which gives it a hair more capacity. There are many other improved reamer designs as well with 30, 33, 37, and 40 degree shoulders and I’m sure all are capable of great accuracy.

Tho I felt my original reamer design needed some tweaking because the accuracy level seemed to be about the same in two completely different rifles. First was a Defiance single shot with a 30” 8 twist Broughton barrel. Second rifle that I am currently using is a Kelby Atlas action with 26” 9 twist carbon fiber Proof barrel. Both shot well but not quite at the level I would like. The Defiance rifle would shoot around 2”-2.5” at 500 yards. Current rifle with the Atlas action can post 1.5” groups at 500 yards on a good day and usually always under 2” (prone with a bipod). So it’s good, but I think I can do better.

My third rifle that is in progress will be based on a BAT HR action with a 26” 10 twist Hart barrel but will have my newly designed chamber. I believe the new reamer design coupled with the superior BAT action and a slower 10” twist using the 220gr will help dial in a little better accuracy to get me down in that 1/4 MOA area where I want to be.

The one thing I can say with a fair amount of confidence is to stay away from 8” twist barrels with anything lighter than the 245gr Berger. 9” twist will even shoot the 245s pretty well and any bullet lighter than that really good. With the 220gr and 215gr weight bullets at the high velocities the NMI can deliver, I think a 10” twist will make them shine best.

 

[Bodhisafa]

Does Alex Wheeler have an LE Wilson seater or do I provide one for him to ream?

 

[rhovee]

Provide a blank

 

[X-Caveman]

I went out yesterday and ran 199gr Hammer Hunters to pressure in Alex's chamber for the 230 class pills. I made a mess of things early. I don't know if it was me, the load, the barrel settling in (was squeaky clean to start). It was grim at first but maybe started to come together later. In the end, I didn't learn much with regard to accuracy potential, but I have a list of things to try differently next time out.

I figured I would share this here for the collective knowledge base. I haven't seen anyone try these bullets yet. They are available and the 110gr 6.5 bullet has performed well on 2 white tail and a few TX hogs for me. My goal is a nilgai (possibly elk?) hunting load that I can develop a lot of confidence in out to about 500M. I also want to see what it will do to a pig or two. For these purposes, I think there's potential. There's certainly plenty of speed. I stopped at 91.0 @ 3,280 FPS.

26" Proof 1-9
Pierce 5 Port
Stiller Tac338 single load
McMillan A5
Sightron SIII 6-24 FFP
About 13.5# as pictured. Not bad to shoot. Terrible to stand beside when someone else is shooting.

Here's the bullet at touch.


My Set up...



The data/ notes...


Last 6 at 200 yards...

 

[Ledd Slinger]

I tried the 200gr Sierras in my 300 NMIs but just never could get them to shoot very well. I think it may have been due to excessive freebore coupled with too fast of a twist rate. Like you saw with the Hammers, my speed was impressive but but neither of my last two rifles liked them. I did not test them extensively since early results on paper clearly indicated that I would probably end up searching for a needle in a haystack to find the accuracy I wanted. Ended up using the remainder of bullets for fouler rounds. No issues finding accuracy early on with 215s and 230s. I know Alex’s chamber will shoot both the Berger 215s and 230s very well since that’s what it is designed for and both of those bullets are proven to be very effective on elk. But I also believe Berger bullets just flat out shoot better than anything else on the market for 30 cals so I pretty much gave up trying anything else.

But it does look like you might have a node there with the Hammer bullets so will be interesting to see how it turns out at longer ranges.

 

[Ledd Slinger]

And PS: No offense to Ryan, but the Pierce brake is probably one of the least effective brakes I’ve used. The straight 90 degree ports in the rear seem to nullify the recoil reducing effects of the other ports facing to the rear.

Switching to a brake with all ports facing rearward will manage the recoil much better

 

[Dm6]

And PS: No offense to Ryan, but the Pierce brake is probably one of the least effective brakes I’ve used. The straight 90 degree ports in the rear seem to nullify the recoil reducing effects of the other ports facing to the rear.

Switching to a brake with all ports facing rearward will manage the recoil much better

I have found the exact opposite I much prefer them over the mbm beast brakes.

 

[ranger0787]

2 very different bullets. You have to pick one. The 230 will work with others in the 260-280 range the 250 is all by it self.

Thinking of running 250gr ATips with 1:8" twist barrel. What is the recommended freebore?

 

[Alex Wheeler]

I have found the exact opposite I much prefer them over the mbm beast brakes.

Ledd is right. The beast is more effective for recoil reduction. I have run them both on the same rifle. I even went from a smaller beast to a bigger muscle. But they have a slightly different design goal as far as I know. The muscle is supposed to have less blast on the shooter because of the 90 degree port, the beast is designed to be as effective as possible. There is a trade off there.

 

[Alex Wheeler]

Thinking of running 250gr ATips with 1:8" twist barrel. What is the recommended freebore?

About .400

 

[ranger0787]

After reading and sifting through a LOT of posts & information here, I've decided to re-think my plan; Now I'll set up to shoot 215gr-230gr from 1:9" twist heavy varmint tapered barrel, 26" long. I really don't like the idea of having a barrel set up to shoot 1 bullet, single feed, no magazine feed. I think I'll still go with the 35° Improved shoulder version as well. I'll take your advice and go with the Borden Bigfoot. I have a gunsmith checking the MDT ACC Chassis to see if it's possible to inlet for that action.

 

[Ledd Slinger]

I have found the exact opposite I much prefer them over the mbm beast brakes.

That’s fine if you prefer the Piercision. Whatever makes you happy is all that matters.

But no doubt there are other brakes more effective at reducing recoil. That’s just a fact. And MBM isn’t the only option. I recently found a new brake option that does one hell of a great job. Could even be slightly better than a mbm beast, but it’s too close to tell. One thing that is better is that there is not as much muzzle blast in the face from this new brake I’m working with. The mbm beast does send blast down at a pretty steep angle. This one not quite so bad. Have had 4 different brakes on the same 338-375R rifle so far. Brake before the current brake was a piercision. The difference in recoil reduction is night and day after removing the piercision and going with this new option which uses an all rearward port design very similar to the mbm beast.

I hear the bastard brakes are pretty good but I’ve never tried them because they are too expensive and too ugly! Lol

 

[Tucker65]

A question for the guys that have tried different brakes on their rifles. Say you work up a great load and have it all dialed in and verified out to the farthest distances you plan on using the rifle. When changing to a different brake have you found that now you need to redo all your load development, or has the different brake, and or weight of the brake not affected you previous great load.

John

 

[Alex Wheeler]

John, any time you change something hat has an effect on barrel harmonics just assume it will have an effect on the load. It may not have a huge effect in some cases, but may in others.

 

[Ledd Slinger]

A question for the guys that have tried different brakes on their rifles. Say you work up a great load and have it all dialed in and verified out to the farthest distances you plan on using the rifle. When changing to a different brake have you found that now you need to redo all your load development, or has the different brake, and or weight of the brake not affected you previous great load.

John

What Alex said is spot on.
In my limited experience, changing brakes results in having to make small adjustments to loads. My few rifles I’ve done this with always shoots the same powder and bullet really well after a brake change, and generally using the same charge weight area. So I wouldn’t say that I’ve ever had to “redo” or start all over on load development. More just make some tweaks to it. It seems like it makes the node shift. That would be the change in harmonics Alex is talking about. So where I was charging the cases right in the middle of a node before, now that same charge weight might be riding on the edge of the node.

Your point of impact will most likely shift as well. So even if you don’t need to tweak the load, you’ll probably have to re-zero your scope and shoot all your distances again.

 

[Tucker65]

ALex and Ledd Slinger thanks for the response and that's kinda what I expected. I have Ryan's brake on my 300 Norma Improved now and while it's good, I just thought with the big side ports it would be better. I just might have to try the other brakes mentioned sometime but with the lack and crazy cost of components lately I think I'll just wait for things to calm down a bit.

John

 

[Ledd Slinger]

ALex and Ledd Slinger thanks for the response and that's kinda what I expected. I have Ryan's brake on my 300 Norma Improved now and while it's good, I just thought with the big side ports it would be better. I just might have to try the other brakes mentioned sometime but with the lack and crazy cost of components lately I think I'll just wait for things to calm down a bit.

John

So another thing I found is that bigger ports aren’t always better. There’s a point where larger ports actually start to become less effective at reducing recoil depending on the amount of powder being burned and bore size of the barrel.

Watch this video from Muzzle brakes and more. Notice that the first brake he tests on the 300 win mag is his normal 5 port beast brake which reduces recoil the best of them all. Then pay attention to where the 5 port “Super” beast brake with much larger ports lands on the scale. It is less effective than the standard beast with smaller ports. Now the 5 port super beast would probably do better than the normal 5 port beast on something like a 375 CheyTac or maybe even a 338 Lapua Improved. But on a large 30 cal round it wasn’t as effective.

The smaller ports is most likely another reason why this new 5 port brake I’m using is more effective than the Piercision which has very large ports. Of course I don’t have a test sled, but I can definitely ‘feel’ the difference on my shoulder and ‘see’ the difference with how much easier it is to spot impacts downrange. Below are photos of the brake I’m using that replaced the Piercision I had on the rifle before this. This is a sendero contour barrel .830” at the muzzle. 338 bore running Berger 250gr bullets around 2950 fps. This brake also weighs less and looks better since there’s not nearly as much steel hanging off the end of my barrel.

 

[Dm6]

That’s fine if you prefer the Piercision. Whatever makes you happy is all that matters.

But no doubt there are other brakes more effective at reducing recoil. That’s just a fact. And MBM isn’t the only option. I recently found a new brake option that does one hell of a great job. Could even be slightly better than a mbm beast, but it’s too close to tell. One thing that is better is that there is not as much muzzle blast in the face from this new brake I’m working with. The mbm beast does send blast down at a pretty steep angle. This one not quite so bad. Have had 4 different brakes on the same 338-375R rifle so far. Brake before the current brake was a piercision. The difference in recoil reduction is night and day after removing the piercision and going with this new option which uses an all rearward port design very similar to the mbm beast.

I hear the bastard brakes are pretty good but I’ve never tried them because they are too expensive and too ugly! Lol

I guess I should rephrase that. I found the Piercision brake much more pleasant as it has no noticeable muzzle blast towards the shooter. The beast is more effective at straight up recoil reduction though. I just thought that it had too much concussion for the shooter. My rifle came out at about 9.5lbs and is a dream to shoot with Ryan’s break.