28n 155 hammers and n570

[JMack]

Ryan Pierce and others who do a lot of 28 nosler stuff have mentioned the need for cleaning very often. I think he said 30 rounds. I also use n570 and have to get that ring out every 20-30 rounds. Huge difference in accuracy.

I only shot 9 times so far using N570 the ones I posted above were it. The other 80 or so rounds have been either factory or just tinkering to get the barrel broken in and it seems like it's really settling in nice with the 160 accubonds

 

[JMack]

I think you are not building enough pressure to get consistent burn. The last 28n that we loaded with n570 and the 155g HH we started at 84g and finished at 87g with a vel of 3470 fps. This was with Nosler brass which is soft. 3.50" coal. Loaded another with the same and finished at 88g with a vel of 3340 fps. The slow powder will do better with some pressure. Work up carefully.

I have enough to run it up to 87 see what that gets me

 

[kfreeze]

Chrono's like the pro chrono can be sensitive to the amout of sunlight some times. (I use a pro chrono too) The caldwell ones I've seen are really bad. I just let my groups and pressure signs tell me what to do. Then I use a chrono to get an estimate to put me on steel and use the drop to tell me velocity.

 

[smokepoler]

You may want to invest in a Teslong borescope for checking your cleaning regimen. The carbon ring might still be there. Patches will ride over hardened carbon.

 

[epoletna]

Can you use someone's Labradar to check your chronograph? In the days before I got a Labradar I used a Shooting Chrony. My experience with that was that it either registered a believable velocity or gave me a "no reading" error message, but (as far as I know) never gave me specious readings. I have been very happy with my Labradar.

 

[JMack]

Can you use someone's Labradar to check your chronograph? In the days before I got a Labradar I used a Shooting Chrony. My experience with that was that it either registered a believable velocity or gave me a "no reading" error message, but (as far as I know) never gave me specious readings. I have been very happy with my Labradar.

I'll have to check around none of my buddies have a labradar

 

[Elk Hunter 338]

Something weird going on can't put my finger on it. ordered a sample pack and just started tinkering here are some results:
This is with ADG brass 2x fired, CCI magnum 250 primers jumping .03" using a prochrono

85gr (1-1/2" group @ 100)
1st 3127
2nd 3176
3rd 3209

85.5 (3" group @ 100)
1st 3158
2nd 3222
3rd 3163

86.0 (.63" group @ 100)
1st 3172
2nd 3085
3rd 3248

i have brand new batteries in the chrono and my load development with the accubonds and retumbo has been consistent with no crazy readings all else is equal. What's up with the speeds all over the place?

are you near max with these ....

 

[JMack]

are you near max with these ....

Not that I could see or tell. No signs on primers or brass and no stiff bolt.

 

[Ronald W Schaefer]

I'd repeat that test and borrow my buddy's chrony...I've had 'em go stupid before and that can lead to some frustrations, repetition and real head scratchin' until you figure out the simplest answer...especially a problem in chronies that use sky screens for various lighting conditions...I've also had 'em go stupid when my chrony is too close to the muzzel, especially with magnum rifles. I'd eliminate bad chrony first before moving on to the more mysterious causes b/c your results are frankly kind of weird.

 

[dxlbaile]

Another vote for looking for carbon ring.. Amazing the difference it makes when you clean it out. If you don't have a ring on inspection I would really think your chrono is off..
I shoot a ton of 28 Nos and you have to clean religiously every 20-30 or you will see crazy pressure.. Not just normal cleaning, get brush with some IOSSO and work the crap out of your throat area.. You will be suprised what comes out.

 

[Elk Hunter 338]

Not that I could see or tell. No signs on primers or brass and no stiff bolt.

keep them there and go till pressure signs should stabilize out... usually extreme large kernel powders need to be at the top end of working load and pressures .. also if your burning that bulky powder expect to clean a ton and like posted before get er down to metal in the throat area and keep a cleaning kit handy

if it was me w/155 gr i would go with h1k or 7977 youll get those speeds easy and have a powder that doesn't burn like a locomotive

 

[JMack]

Another vote for looking for carbon ring.. Amazing the difference it makes when you clean it out. If you don't have a ring on inspection I would really think your chrono is off..
I shoot a ton of 28 Nos and you have to clean religiously every 20-30 or you will see crazy pressure.. Not just normal cleaning, get brush with some IOSSO and work the crap out of your throat area.. You will be suprised what comes out.

I'll clean it some more I gotta find someone with a bore scope

 

[JMW67]

I'll clean it some more I gotta find someone with a bore scope

you can order a teslong scope off amazon pretty darn cheap not the best but will serve just fine for what you need it for

 

[BKM]

While N570 is a great powder and can yield some impressive velocities it is by far the dirtiest powder I've ever used.