New 300 Norma Mag build Twist rate question

[Scott.Neidrick]

Wondering what a respectable sd would be for 300 Norma. I am just starting load development for this gun with 25 rounds down the barrel.

With 215 Berger over 87.5 of N570 I’m getting 3071 fps and an sd on 8.3. Planning on shooting this load or 230 hybrids if i can locate them out to 2200.

I know its early but the sd’s look promising and the accuracy is under .5 moa so far.

I use N570 at about the same charge weight - best SDs with my new barrel were between 4-9 . My worst SDs were around 10-15. Id recommend using the 220 LRHT (better BC than the 230s and lighter) I was getting 3150-3250fps depending on charge. From my experience - I would say you have a hammer - I wouldn't change too much, its time to take it out to distance!

 

[robb_va]

Yes I did. 1:8 Bartlein 5R 30" 3030fps - separated after 4-5 shots. You may have good luck, but the Norma is pushing the RPM - add in a hot day / multiple shots, and you may see the same effect. Recommend switching to Berger and having high confidence.

Thanks.

 

[Blkbird6]

Wondering what a respectable sd would be for 300 Norma. I am just starting load development for this gun with 25 rounds down the barrel.

With 215 Berger over 87.5 of N570 I’m getting 3071 fps and an sd on 8.3. Planning on shooting this load or 230 hybrids if i can locate them out to 2200.

I know its early but the sd’s look promising and the accuracy is under .5 moa so far.

I would think that N570 is too slow for such a light round. try something like H1000 for better MV

 

[Blkbird6]

Hey All, great thread! I just came across this thread and has some data to provide that may help someone. I built a 30” 1-8 twist Bart 5R 300NM. Purpose built for 250 ATIPS. Pushing at 3030 FPS (not a hot load-no pressure signs). The ATIPS are exploding. Ran 300 rounds with no issues but at a modest shot string rate. During a competition, putting 10 down the tube at a time, some came apart (likely extra heat etc). I’m switching to the 245 Bergers to see if they will hold up. I will say the ATIPS were very good when they actually worked. I’ve taken it out to 2,700 yards with great consistency. Just some food for thought to help the next guy! Thanks!

what powder are you using in this?? I'm just about to start loading the 250 atips...

 

[Scott.Neidrick]

what powder are you using in this?? I'm just about to start loading the 250 atips...

N570 and N565. I wish you good luck- I highly recommend Berger to reduce the potential of future stress. The first few ATIPs shot fine- then through the break-in, they started to separate- it took a while for me to figure out what was happening. If you don’t see a a bullet impact the target- you know what happened

 

[robb_va]

Yes I did. 1:8 Bartlein 5R 30" 3030fps - separated after 4-5 shots. You may have good luck, but the Norma is pushing the RPM - add in a hot day / multiple shots, and you may see the same effect. Recommend switching to Berger and having high confidence.

Interesting. With my old barrel, a 1:8, 27 inch 5R, I never had a problem with the 250s. I fired a fair amount of them through it at 3k using N570. I just started using them again with my current barrel, a 1:8, 27 inch 5R. I'm using RL33 at 2950. So far I have had no issues. I did have an issue with the 230s with the old barrel at 3150 when the barrel got hot, but I guess that could be expected at 284,000 RPMs.

 

[Scott.Neidrick]

Interesting. With my old barrel, a 1:8, 27 inch 5R, I never had a problem with the 250s. I fired a fair amount of them through it at 3k using N570. I just started using them again with my current barrel, a 1:8, 27 inch 5R. I'm using RL33 at 2950. So far I have had no issues. I did have an issue with the 230s with the old barrel at 3150 when the barrel got hot, but I guess that could be expected at 284,000 RPMs.

Ya, I have heard people having success- I don’t know what is causing some success vs failure- I just think the RPM is on the edge for the thin jacket. I had the same issue with my 6.5 PRC- so I am staying away from ATIPs. Also, when I did the Doppler radar with Applied Ballistics- the ATIPs had a 3% BC variation. You want 1% and no more than 2%- so I switched to Berger and had a happier life. I also contacted Hornady many time to help- but they keep blowing me off so I’m done with that customer service.

 

[robb_va]

Ya, I have heard people having success- I don’t know what is causing some success vs failure- I just think the RPM is on the edge for the thin jacket. I had the same issue with my 6.5 PRC- so I am staying away from ATIPs. Also, when I did the Doppler radar with Applied Ballistics- the ATIPs had a 3% BC variation. You want 1% and no more than 2%- so I switched to Berger and had a happier life. I also contacted Hornady many time to help- but they keep blowing me off so I’m done with that customer service.

Could you post the 250 ATIP and 245 EOL sheets that you got when you did the doppler radar tests with AB?

 

[Scott.Neidrick]

Could you post the 250 ATIP and 245 EOL sheets that you got when you did the doppler radar tests with AB?

 

[Scott.Neidrick]

I don’t have the 245 EOL sheet yet- I can post that in June when I do my testing.

 

[Scott.Neidrick]

I just wanted to send a quick update about the 245 LRHTs: I went out and shot 50 of them at about 2950 FPS. They worked well. I didn't notice anything super significant compared to the 245 EOLs, except that the LRHTs required about 0.1 to 0.2 less mils of elevation at a mile when compared to my kestrel 245 EOL CDM. Overall, I had no issues with them. After I go to the NF match in June, I will post my AB Doppler data for the bullets.

 

[ViperACR]

I used 250 Atip at 2930 with a 9.5” twist and have had great results. Finished 3rd at 2022 NF match.

 

[moosemeat]

I think just cause it works in a win mag does not mean it will work in a Norma mag. The added velocity, especially with how people around here load, is likely to push the RPM up around 270,000 and have more failures.