A cooler filled with ice/water and a microfiber towel does a pretty good job IMHO. Proved it works in a several matches where second relay group size was always minimum of twice the size vs. being equal or smaller.
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7-300 Norma Mag Improved. IT’S ALIVE!!
- Thread starter Huntnful
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Huntnful
Well-Known Member
Just got the barrel all polished up after 40 rounds of H1000 and it looks MUCH better than the last barrel. Apparently 5 shot groups of N570 is devastating to the throat in this cartridge lol. And slow rolling H1000 is super mild.
Hardly a crack
Hardly a crack
Quicksilver338
Well-Known Member
Fake, that's a different barrel, can't fool me.
Huntnful
Well-Known Member
Dont show people my hack job
Quicksilver338
Well-Known Member
Well you're not wrong, technicallyIt is a different barrel
It looks so much better than your old barrel because Barehandlineman11 did you a favor and put a 30 cal barrel on there so that the bullet would have less contact with the rifling and gives room for the flame to spread out through the barrel more evenly and not fire crack the throat. The man is a genius.
It looks so much better than your old barrel because Barehandlineman11 did you a favor and put a 30 cal barrel on there so that the bullet would have less contact with the rifling and gives room for the flame to spread out through the barrel more evenly and not fire crack the throat. The man is a genius.
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meatyrem
Well-Known Member
Not sure if it's been mentioned but what about RL 33 or Ramshot LRT? These two are basically hugging 570 so should be a suitable choice and may help prolong barrel life. Not sure how high flame temp on either one is
RH300UM
Well-Known Member
For what it's worth I tried both of these in my 7-300 nmi. Neither gave accuracy or performance for me.
RL33 and LRT gave huge es and burned extremely dirty. 26 inch barrel.
Top 3 for performance are N570, Retumbo and RL26 for performance and accuracy. H1000 was just too slow for me in my rifles.
I use N570 my sons rifle uses Retumbo
Huntnful
Well-Known Member
Great info, thank you!
Huntnful
Well-Known Member
UPDATE! CHARGE WEIGHTS AND SPEEDS
I can't edit my original post to share my most up to date data collection. But hopefully that title helps grab anyone's attention that's scrolling through the thread possibly wanting to build one!
After doing quite a bit more firings on the brass, I've found some more realistic and better data regarding pressures, charge weights, and speeds.
Data out of 26" barrel for reference. These are max charges in my chamber, with this design IMO. They don't overly expand the case web, or cause any bolt lift, on multiple firings.
180gr. Bullets:
H1000 - 83gr. 3170fps
N570 - 90gr. 3300fps
190gr. Bullets
H1000 - 80gr. 3070fps
N570 - 87gr. 3200fps
H1000 has also been SUPER mild on the chamber. I'm now switching back to 5 shots groups without cooling because of the lack of cracking. I know it doesn't give hotrod speeds. But I get to use Lapua brass, mild charge weights, and still match, if not beat a 28N maxed out with N570 in most cases.
For reference, my old 28 nosler load was 82gr. N570 for 3030fps (I know some people shoot them hotter) with a 195 berger in a 26" barrel. At 80gr. H1000 this cartridge beats that by a few FPS. So this chamber with a lower charge of H1000 should theoretically get better barrel life, while outperforming a 28N.
I still have 3 more 7mm barrels coming for lots more testing. Some barrels might only see N570 and 190gr.+ bullets, and some might only see H1000 and 180gr. bullets.
Overall, I'm definitely happy with the cartridge and the options it provides for the bigger 7mm bullets. Both H1000 and N570 have held 20 ES for long shot strings with CCI 250 primers.
I didn't add retumbo because I stopped shooting it and testing it after it was giving the highest ES's and worst groups. But the speeds and charge weights pretty much land exactly between H1000 and N570.
I can't edit my original post to share my most up to date data collection. But hopefully that title helps grab anyone's attention that's scrolling through the thread possibly wanting to build one!
After doing quite a bit more firings on the brass, I've found some more realistic and better data regarding pressures, charge weights, and speeds.
Data out of 26" barrel for reference. These are max charges in my chamber, with this design IMO. They don't overly expand the case web, or cause any bolt lift, on multiple firings.
180gr. Bullets:
H1000 - 83gr. 3170fps
N570 - 90gr. 3300fps
190gr. Bullets
H1000 - 80gr. 3070fps
N570 - 87gr. 3200fps
H1000 has also been SUPER mild on the chamber. I'm now switching back to 5 shots groups without cooling because of the lack of cracking. I know it doesn't give hotrod speeds. But I get to use Lapua brass, mild charge weights, and still match, if not beat a 28N maxed out with N570 in most cases.
For reference, my old 28 nosler load was 82gr. N570 for 3030fps (I know some people shoot them hotter) with a 195 berger in a 26" barrel. At 80gr. H1000 this cartridge beats that by a few FPS. So this chamber with a lower charge of H1000 should theoretically get better barrel life, while outperforming a 28N.
I still have 3 more 7mm barrels coming for lots more testing. Some barrels might only see N570 and 190gr.+ bullets, and some might only see H1000 and 180gr. bullets.
Overall, I'm definitely happy with the cartridge and the options it provides for the bigger 7mm bullets. Both H1000 and N570 have held 20 ES for long shot strings with CCI 250 primers.
I didn't add retumbo because I stopped shooting it and testing it after it was giving the highest ES's and worst groups. But the speeds and charge weights pretty much land exactly between H1000 and N570.
KH_Outdoors
Well-Known Member
It honestly feels like the first barrel is just for learning purposes lol. I also personally feel like these bigger magnums are more of a passion project, than a realistic necessity haha. I love crunching numbers and learning new cartridges and stuff for sure. But I know I would have no problem just stacking up animals with a 6.5 PRC and 147 ELDMs
Next years project then?
Huntnful
Well-Known Member
Hahaha never. @Barehandlineman11 said he won't build me a 6.5-300 WSM thoughNext years project then?
