300 Norma Improved 35 degree

[shoot4fun]

Was also wondering if anyone used the cream of wheat with faster burn rate powders to get a 90 percent case blowout prior to shooting the bullets to help conserve barrel life. If so what is your load recipes? Thanks

I was fortunate to get 200 rounds of Berger Factory 300NM ammo with my rifle. It shoots extremely well and makes beautiful improved brass. I should have brass for my lifetime.
BTW I have no idea what my free bore is but have fired 215 Hybrids and 230 OTM with great results.

 

[Yote Hunter]

Thank y’all for your advice. Expecting my new 300 Norma Improved to be delivered from Alex any day now. Can’t wait!

 

[Dogsdown]

Anyone have any suggestions where I could find a quality bore guide for a Bat “M” 300 Norma Improved?

 

[Alex Wheeler]

pma tool, call them

 

[Dogsdown]

Thank you Sir!

 

[ranger0787]

So, I had an interesting day yesterday when taking my newly-built 300 NMI 35° Improved out to fireform initial brass...The rifle is a Borden Bigfoot inlet & bedded into an MDT ACC chassis by Borden Accuracy, 9 twist 28" long Bartlein 5R barrel, Triggertech Diamond Pro trigger.

I loaded 100 pieces of virgin Lapua 300 Norma brass with 86.00gr of H1000, Sierra #2231 200gr Match Kings, CCI-250 mag primers, CBTO: 2.860", COAL: 3.731". I installed the Pressure Trace 2 system with the strain gage epoxied under the barrel inside the MDT Chassis. I shot off a Rodzilla front rest, no brake, no suppressor.

The first 25 shots were uneventful. All rounds fired, recoil was a little stout, but manageable, no pressure signs, chrono velocities averaged 2995'/sec, chamber pressures were between 39k-42k with no spikes in pressure curves, nice parabolic curves that overlayed each other.

The barrel was scrubbed clean with Boretech carbon remover after 25 rounds. The next batch of 25 started. Shot #37 felt "Wierd"; WAY more recoil and bolt almost impossible to open. I had to use a 2x4 to open the bolt & unlock and use the 2x4 to move the bolt to the rear. Muzzle Velocity on Labradar was 3458! And pressure spike recorded on the pressure trace flatlined at 69k psi. Primer completely flat, +ejector mark, case head press-fit to bolt face & wouldn't eject out of loading port , case OAL +.012" longer than all other fired cases, primer was not pierced. The body/shoulder junction was sharply defined as opposed to the more-rounded shoulders of all the previously fireformed brass. I looked over the rifle, dry-fired a few times and loaded another round. "Click", no bang. Ejected the live round & primer was struck by firing pin. MAYBE not as deep as the others but difficult to tell. 2nd round chambered, "Click", no bang again. Everything halted. Packed up and went home.

WTF Happened??

Was shot #37 oal empty new case just .012" too long and possibly crimped the bullet upon closing the bolt and therefore spiked mv & pressure? Did the excess pressure elongate the brass the extra .012"? Powder charges from same 1lb jug weighed out to last kernel and checked with a flashlight prior to bullet seating. Powder column visible @ body/shoulder junction inside cases.

What could possibly explain the click-no-bangs after the overpressure round? Could really use some input from those more-experienced here...

This is my 1st AI/Wildcat...

 

[Alex Wheeler]

I'd call Jim first. We'd just be guessing on here.

 

[ranger0787]

Anyone have any suggestions where I could find a quality bore guide for a Bat “M” 300 Norma ImproveWhen I vistie

Anyone have any suggestions where I could find a quality bore guide for a Bat “M” 300 Norma Improved?

When I visited Brunos in Phoenix after the 2022 SWN, He had a decent sized plastic bin of various bore guides for various cartridges. I bought 4 different ones. One for the 300 Norma I built. all had solvent ports, made of HDPE-type material. Maybe call them & see what they have left?

 

[Ledd Slinger]

So, I had an interesting day yesterday when taking my newly-built 300 NMI 35° Improved out to fireform initial brass...The rifle is a Borden Bigfoot inlet & bedded into an MDT ACC chassis by Borden Accuracy, 9 twist 28" long Bartlein 5R barrel, Triggertech Diamond Pro trigger.

I loaded 100 pieces of virgin Lapua 300 Norma brass with 86.00gr of H1000, Sierra #2231 200gr Match Kings, CCI-250 mag primers, CBTO: 2.860", COAL: 3.731". I installed the Pressure Trace 2 system with the strain gage epoxied under the barrel inside the MDT Chassis. I shot off a Rodzilla front rest, no brake, no suppressor.

The first 25 shots were uneventful. All rounds fired, recoil was a little stout, but manageable, no pressure signs, chrono velocities averaged 2995'/sec, chamber pressures were between 39k-42k with no spikes in pressure curves, nice parabolic curves that overlayed each other.

The barrel was scrubbed clean with Boretech carbon remover after 25 rounds. The next batch of 25 started. Shot #37 felt "Wierd"; WAY more recoil and bolt almost impossible to open. I had to use a 2x4 to open the bolt & unlock and use the 2x4 to move the bolt to the rear. Muzzle Velocity on Labradar was 3458! And pressure spike recorded on the pressure trace flatlined at 69k psi. Primer completely flat, +ejector mark, case head press-fit to bolt face & wouldn't eject out of loading port , case OAL +.012" longer than all other fired cases, primer was not pierced. The body/shoulder junction was sharply defined as opposed to the more-rounded shoulders of all the previously fireformed brass. I looked over the rifle, dry-fired a few times and loaded another round. "Click", no bang. Ejected the live round & primer was struck by firing pin. MAYBE not as deep as the others but difficult to tell. 2nd round chambered, "Click", no bang again. Everything halted. Packed up and went home.

WTF Happened??

Was shot #37 oal empty new case just .012" too long and possibly crimped the bullet upon closing the bolt and therefore spiked mv & pressure? Did the excess pressure elongate the brass the extra .012"? Powder charges from same 1lb jug weighed out to last kernel and checked with a flashlight prior to bullet seating. Powder column visible @ body/shoulder junction inside cases.

What could possibly explain the click-no-bangs after the overpressure round? Could really use some input from those more-experienced here...

This is my 1st AI/Wildcat...

Initial barrel break in procedures vary widely and are debated quite a bit but I personally would never shoot a brand new barrel 25 times before the very first cleaning. And that is definitely not what Bartlein recommends. Then if you didn’t get it cleaned enough, you could have developed a lot of copper and carbon ring build up that suddenly spiked pressures when it got bad enough. Don’t know what your cleaning regiment involves but the only way to know you are doing it right is to use a borescope for verification.

Could have overcharged the case as well even if you thought you were being careful. We’ve all done it before and those who haven’t will do it at some point if you load for long enough.

Below is the barrel break in procedure straight off the Bartlein website. A little research and reading can save you a lot of headache

 

[ranger0787]

Initial barrel break in procedures vary widely and are debated quite a bit but I personally would never shoot a brand new barrel 25 times before the very first cleaning. And that is definitely not what Bartlein recommends. Then if you didn’t get it cleaned enough, you could have developed a lot of copper and carbon ring build up that suddenly spiked pressures when it got bad enough. Don’t know what your cleaning regiment involves but the only way to know you are doing it right is to use a borescope for verification.

Could have overcharged the case as well even if you thought you were being careful. We’ve all done it before and those who haven’t will do it at some point if you load for long enough.

Below is the barrel break in procedure straight off the Bartlein website. A little research and reading can save you a lot of headache

View attachment 1327732

I also brought my Teslong borescope along with me to the range, I did borescope afterwards, noticed carbon in the proximal 1/3rd, scrubbed out with Boretech carbon remover, slight copper streaking near corners of the lands/grooves, continued scrubbing with patch-wrapped bore brush, also ensured no carbon ring. Overpressure round didn't happen until shot #12/25 of 2nd batch of #25. As far as powder charge goes, I weigh out to the last kernel of powder on an Fx120i scale. I spoke to Jim Borden today and will be sending all my data, over-pressure case, bolt, trigger, and regular fireformed case tomorrow. Thanks.

 

[Ledd Slinger]

I also brought my Teslong borescope along with me to the range, I did borescope afterwards, noticed carbon in the proximal 1/3rd, scrubbed out with Boretech carbon remover, slight copper streaking near corners of the lands/grooves, continued scrubbing with patch-wrapped bore brush, also ensured no carbon ring. Overpressure round didn't happen until shot #12/25 of 2nd batch of #25. As far as powder charge goes, I weigh out to the last kernel of powder on an Fx120i scale. I spoke to Jim Borden today and will be sending all my data, over-pressure case, bolt, trigger, and regular fireformed case tomorrow. Thanks.

Yeah we all weigh our charges very precisely. I weigh down to the kernel as well. But when loading a large volume of rounds, it can get monotonous and boring. Our minds will wander or we can encounter some sort of distraction. Can load the wrong amount without even knowing it. It happens. I loaded a round way over the charge weight I should have in a 358 Norma Magnum many years ago. Shot the 225gr bullet across the chronograph and it said 3275 fps. Thought “WOW! That’s fast!” Went to open the bolt and it was locked up so tight you’d swear it had been welded shut.

The amount of speed you saw on the chronograph seems extremely excessive for a fouled barrel. The only rational explanation in my mind is that you overcharged the case. I don’t see how you could have achieved 3458 fps any other way. And unfortunately nobody, including you or Jim Borden, will be able to say you did or didn’t overcharge the case with 100% certainty. I would pull the remaining rounds and double check charge weights. But even that might not tell you anything if it was just the one round that was overloaded.

Be interesting to see what Jim says. At least he will be able to get the ignition system in the action firing properly again.

 

[Alex Wheeler]

Bullet central should have dies in a week

 

[Ranger188]

Anyone tried IMR 7977 or 8133?

 

[ranger0787]

Yeah we all weigh our charges very precisely. I weigh down to the kernel as well. But when loading a large volume of rounds, it can get monotonous and boring. Our minds will wander or we can encounter some sort of distraction. Can load the wrong amount without even knowing it. It happens. I loaded a round way over the charge weight I should have in a 358 Norma Magnum many years ago. Shot the 225gr bullet across the chronograph and it said 3275 fps. Thought “WOW! That’s fast!” Went to open the bolt and it was locked up so tight you’d swear it had been welded shut.

The amount of speed you saw on the chronograph seems extremely excessive for a fouled barrel. The only rational explanation in my mind is that you overcharged the case. I don’t see how you could have achieved 3458 fps any other way. And unfortunately nobody, including you or Jim Borden, will be able to say you did or didn’t overcharge the case with 100% certainty. I would pull the remaining rounds and double check charge weights. But even that might not tell you anything if it was just the one round that was overloaded.

Be interesting to see what Jim says. At least he will be able to get the ignition system in the action firing properly again.

86.00gr of Varget was used; accidentally left in the hopper from loading .308 Win. 15 rounds loaded with Varget, 50 loaded with H1000. HUGE mistake! Thank God nothing, nor me was damaged.

 

[Bodhisafa]

When will bullet central have 300 Norma improved dies?

 

[Alex Wheeler]

They have them now

 

[Bodhisafa]

They have them now

Didn’t see it on the website

 

[Alex Wheeler]

You have to call them.

 

[Ledd Slinger]

My 3rd build on the 300 NMI. Made some chamber tweaks and running a 10” twist to cater specifically for the Berger 215-220gr this time around. I do have 230gr as well and might test them. Built on a Bat HR with Bix TS Pro, WOOX stock, Hart barrel. Went all satin black with this one

 

[rhovee]

I originally tried to shoot the 215’s and it just wouldn’t do it with H1000 ish burn rate powders in the 3050-3100 range. They did shoot good faster with N570.