300 Norma Improved 35 degree

[otnot]

My gun really likes H50BMG. With a 230 grain 95.5 gr. gives me 3025 fps. With a 215 grain, 98 gr. gives me 3150.

 

[schw15]

So I have something weird going on. Starting at 78 grains opens fine working my way 78.5 first one opens hard but the next 4 open easy. 79 grains open hard. 79 grains again open like butter. 79.5 open fine another batch of 79.5 of 6 all open fine besides 1.

I have 3 barrels all done at the Sametime to save barrel wear I fireformed 100 brass on each barrel to get 300 formed. I need 200 for the nightforce challenge. I'm not too sure that isn't my issue

 

[Tucker65]

So I have something weird going on. Starting at 78 grains opens fine working my way 78.5 first one opens hard but the next 4 open easy. 79 grains open hard. 79 grains again open like butter. 79.5 open fine another batch of 79.5 of 6 all open fine besides 1.

I have 3 barrels all done at the Sametime to save barrel wear I fireformed 100 brass on each barrel to get 300 formed. I need 200 for the nightforce challenge. I'm not too sure that isn't my issue

What die are you using to size your cases? Have you measured how much the case is getting sized down by the base to see if the die is working for your chamber? I had a couple of custom dies made by one of the die makers off my reamer print. The first one worked great, the second one showed stiff bolt lift well below the loads I had previously used. I sent the die back and they said it was within spec. My reamer was almost identical to Alex's so I ordered a Bullet Central micron die and it size the base down more and all the pressure signs and stiff bolt went away.

 

[schw15]

What die are you using to size your cases? Have you measured how much the case is getting sized down by the base to see if the die is working for your chamber? I had a couple of custom dies made by one of the die makers off my reamer print. The first one worked great, the second one showed stiff bolt lift well below the loads I had previously used. I sent the die back and they said it was within spec. My reamer was almost identical to Alex's so I ordered a Bullet Central micron die and it size the base down more and all the pressure signs and stiff bolt went away.

Using his die now.

 

[L.Sherm]

Is the hard bolt lift at the bottom of the upward lift or top?
I'm wondering if Tucker65 is correct.

 

[L.Sherm]

Using his die now.

Has this brass been used with Alex's die from new?

 

[schw15]

The stiff ones start at the bottom all the way up. I measured fired cases at .200 this round they were .585 the shoulders I did notice on one's that open stuff are longer 2.047 compared to 2.046

 

[schw15]

Has this brass been used with Alex's die from new?

No it has not had another die that I resized most of the brass with that didn't work then ran all brass threw the new die.

 

[schw15]

My avg velocity today berger 220 29 inch barrel n565 78 to 79.5 2980 to 3015.

 

[L.Sherm]

The stiff ones start at the bottom all the way up. I measured fired cases at .200 this round they were .585 the shoulders I did notice on one's that open stuff are longer 2.047 compared to 2.046

So the 2.047 is your fired Case to datum line?

 

[schw15]

I'm using short action customs 35 degree headspace tool. I might have numbers mixed I can run down to check. But measuring from base to spot on shoulder that's what I use to measure when I need to bump back shoulders

 

[L.Sherm]

I'm using short action customs 35 degree headspace tool. I might have numbers mixed I can run down to check. But measuring from base to spot on shoulder that's what I use to measure when I need to bump back shoulders

Have you done the Wheeler method to establish no resistance on a sized case or just measuring a fired case and subtracting .002

 

[Ledd Slinger]

How long has it been since you cleaned the barrel? Maybe good idea to check it with a borescope. When load testing with the NMI, I usually won't run more than a 3 foulers and 20 rounds on target before cleaning again. Definitely wouldn't go over 50 rounds before cleaning for any reason. I've had erratic false pressure signs like you are describing from a little too much carbon in the bore.

Not sure about N565, but N570 will build up a decent amount of carbon in the barrel after 20-30 rounds. RL33 is probably the dirtiest burning powder ive seen. Either way, it's a lot of powder being burnt with each shot so cant run high round counts between cleaning like you can on something smaller like a 6mm. Might be time for a good hard scrubbing with a bronze brush to get excessive carbon out.

Makes sure you patch the chamber clean and keep the brass cleaned off your bolt face too.

 

[schw15]

Have you done the Wheeler method to establish no resistance on a sized case or just measuring a fired case and subtracting .002

I measure but I did take my bat apart and use that method as well in the beginning.

 

[schw15]

How long has it been since you cleaned the barrel? Maybe good idea to check it with a borescope. When load testing with the NMI, I usually won't run more than a 3 foulers and 20 rounds on target before cleaning again. Definitely wouldn't go over 50 rounds before cleaning for any reason. I've had erratic false pressure signs like you are describing from a little too much carbon in the bore.

Not sure about N565, but N570 will build up a decent amount of carbon in the barrel after 20-30 rounds. RL33 is probably the dirtiest burning powder ive seen. Either way, it's a lot of powder being burnt with each shot so cant run high round counts between cleaning like you can on something smaller like a 6mm. Might be time for a good hard scrubbing with a bronze brush to get excessive carbon out.

Makes sure you patch the chamber clean and keep the brass cleaned off your bolt face too.

I just cleaned it then shot like 10 rds yesterday then I shot today. During the nightforce might have to shoot 70 plus rounds the first day so I try to not clean so I find a load that works just in case at match it acts up. I'm going to scrub the barrel really good but it's odd that I get 4 fine then 1 not. I'm not to sure it isn't from foreforming with multiple barrels and the die I was using. I'm going to run a test I have a few virgin brass that I will form and then load at different charges and get a few firings on them to see if that I'd truly the issue. At least then I can cross that off and move to next thing.

 

[Ledd Slinger]

I just cleaned it then shot like 10 rds yesterday then I shot today. During the nightforce might have to shoot 70 plus rounds the first day so I try to not clean so I find a load that works just in case at match it acts up. I'm going to scrub the barrel really good but it's odd that I get 4 fine then 1 not. I'm not to sure it isn't from foreforming with multiple barrels and the die I was using. I'm going to run a test I have a few virgin brass that I will form and then load at different charges and get a few firings on them to see if that I'd truly the issue. At least then I can cross that off and move to next thing.

Yeah should be fine then, but check the cleanliness with a borescope to be sure. Sometimes the carbon deposits in front of the lands can be really stubborn to remove

 

[L.Sherm]

Try 3 new brass from the beginning and size with Alex's die only and cycle them 3 or 4 times, if there's no pressure signs that will tell you wether or not its a sizing issue.
I wouldnt be afraid to bump .003 either.

 

[schw15]

Try 3 new brass from the beginning and size with Alex's die only and cycle them 3 or 4 times, if there's no pressure signs that will tell you wether or not its a sizing issue.
I wouldnt be afraid to bump .003 either.

That's my plan hopefully next week get that done. Then gotta buy new brass

 

[schw15]

I was able to shoot the new brass today. Loaded 3 up at different charges. I ended up shooting 78.5 grains with pretty good results. The brass opened good. I did test one that I thought was max and it has a little drag so I will set to the side. I then loaded them 3 and 4 other 1 time fired brass shot a group and got speed all were good besides 2. I took my bolt apart and ran brass with no firing spring ect and they close very smooth and easy but 1.
Group I think will be better it got pretty dark on me and no target I aimed at the man by L. The highest speed was from the brass that opened up hard. I guess I will run it and cull the bad brass to side. I'm not too impressed with speed I was getting same speed out of my 30 noslers with berger 220. I still thing something is up. I'm going to clean the rifle really good tonight and let it sit over night with boretech Carbon remover. I appreciate the help I'm prolly going to move away from these barrels and action and go back to 300 prc or 30 nosler ect.

 

[Ledd Slinger]

Yeah somethings not right. Hopefully it's something as simple as a hard carbon deposit that got missed, but I definitely think you need to go to N570 as well.

I even revamped some specs on my original chamber reamer. First two rifles were on my original specs and current NMI is running on V 2.0 updated specs. Have also tested in 8", 9", and 10" twist barrels. First one had an 8" twist barrel, second had a 9" twist, and the NMI I currently have has a 10" twist. Shot everything from the 215gr Berger all the way up to the 245gr. My current rifle with the updated chamber specs and 10" twist is definitely producing the best speeds across the board, but I have never had any issues developing good speeds with any of my NMIs. It should easily run 100 fps faster than anything a 30 Nosler can do.