OzFclass

I am trying Williada's system, and recently had two very good Bartlein barrels re-throated at the 750-800 round mark. So instead of going to 1000 or more shots and then doing a full RECHAMBER like many do, David recommends a suitable universal Throater be used to just "freshen up" the throat, with the theory being that the next 750 rounds fired should be from a barrel at its absolute peak.
So in my case, I sent the barrels to Matt P with the request that he just go in the minimal amount possible to get a fresh, EVEN cut on each land.
He ended up going in 0.040" to get a perfectly even cut. He had originally chambered both of them to give me an identical "touch" measurement, so comfortably did exactly the same thing again with the re-Throating job.

My original load was 50.7 gr of AR2209 behind 180 gr Berger VLDs , jumped 0.005" for 2820 - 2830 fps .
I am almost out of VLDs but have plenty of 180 gr Hybrids.

So with just 0.040" extra space in the neck of the case (more space equals less pressure)
1) what velocity did my 50.7 gr of 2209 give me with 180 gr Hybrids jumped about "10"?
2) how much AR2209 to get the 180 gr Hybrids back to 2820-2830 fps that I wanted ?

I was quite a long way out , while Mark Fairbairn was spot on.
I am keen to see some guesses from others I will put the correct answers up in 24 hrs

Tony, the Hybrids won't work for you, if you want to get rid of them I'll have them


Seriously, My development with Hybrids was as this; jammed didn't work, then I tried jumping at various distances until 30thou then they started to work.
So, saying that, from 5thou off to 30 isn't a big difference after the throating so it may work out just fine with the same load.
Geoff

I recommend using some Trailboss with a bit of salt filler in the case. Should see you sorted no probs Tony

Tony I would think you would need an extra 0.5gn to 1gn to get back to your velocity especially if you are starting with a soft start jump.

.3gr

1. 2770fps??
2. Around one grain increase to get back to 2820-2830fps is my guess.

Footsore wrote:1. 2770fps??
2. Around one grain increase to get back to 2820-2830fps is my guess.

What Steve said but .2-.3 of a gr ! Regards Graham.

Some points of clarification with regard to nipping up the chamber.

It’s not much, as I am interested in maintaining the original barrel index position and the bullet seating depth with the same projectile. This maybe just one rotation of the barrel depending on the throat wear which is inspected by bore scope and/or casting using Cerrosafe if you want to be pedantic. You have to cut out any oval shape developing due to bullet slap etc. to find clear round barrel. Its like a regular dental checkup preventing little areas of decay growing. The nip is not a normal barrel setback where most take an inch or a chamber length from the barrel tennon. Its just to freshen the throat, keep carbon at bay and lengthen the peak accuracy time of the barrel. It does not reduce velocity significantly by reducing barrel length or change the harmonics much due to barrel length and gun handling.

The length of the nip depends on barrel steel hardness in combination with the powder and seating depth you use.

The use of the correct tool depends on the length of the nip required to cut clean throat and maintain the barrel index position. Those people that use switch barrels have a setup which can be easily monitored for wear.

In this case, you can get away with a universal throat reamer made by PTG which is hand operated PROVIDING it does not significantly extend the throat beyond what would be a normal chase of the lands as they wear, with seating depth anyway. Otherwise, my preferred option is to use the full length reamer.

In actual fact, I use the Universal reamer kept on the original setting as a carbon scraper. It won’t cut out more steel than it originally did and makes short work of crud - back in business after a few blowoffs. Tickle up with Sweets after blowoffs to check for copper then resort to normal cleaning e.g. the bronze brush and Hoppes. If you are going to lap with JB while you are at it, do it before the nip.

The other use I have for the universal throat reamer is when a barrel is new, or I am changing profiles or to a new calibre or changing projectiles. The universal throat reamer is used to determine an appropriate throat length when the full length reamer does not give sufficient throat length to tighten groups as Geoff and many of us have experienced at times with different barrel/bullet combinations when other load development techniques fall short. There is no hard and fast rule for these things as we keep saying, every combo is different. I prefer to lengthen the throat rather than seat the bullets too deep.

For any nip up that requires more than .030”, and in most cases a full rotation of the barrel is in the order of .060” I would use a full length reamer. David.

AAAAAAAAAAAAH ! Footsore .
I didn't think to disqualify Clubmates "who were there" from the Quiz. So Stephen Nelson, you go the back of the class for being a naughty boy.
Your little brother Norm Nelson, on the other hand, goes straight to the top of the Class and can sit beside WildDog, for getting it right !

1) 2777 fps was the velocity obtained with the original powder load of 50.7 gr AR2209, jumping Hybrids 0.010"

2) adding 0.8 gr , to make 51.5 gr AR2209, put me back at approx 2825 fps.

I was hoping for only 0.005 to 0.010 for the "nip", but absolutely trust Matt P in that he had to go to 0.040" to get it perfectly round and even .
It just might be that 180 gr VLDs and Hybrids in a 284 Win have a tendency to lap/wear heavily compared to other combinations. I had Phil Jones (Redback) rechamber a Maddco barrel very recently with 1000 shots through it. He cut the whole tenon off, rechambered , then inspected, and redkons it was still very oval in shape. That meant having to "pick the thread up" after putting the reamer in deeper till he found a clean, round finish that I had asked for.
It had shot 180 gr Hybrids jumped 0.015" for it first 1000 rounds.

I might have an idea how it's going to handle Hybrids after this weekend. Then again it IS North Arm OPM and it's highly possible to leave there without having a bloody clue as to how any load went. This is the home of the most unreadable conditions in Queensland, when it's a bad day, and where grown men have been reduced to tears.

ecomeat wrote:AAAAAAAAAAAAH ! Footsore .
I didn't think to disqualify Clubmates "who were there" from the Quiz. So Stephen Nelson, you go the back of the class for being a naughty boy.
Your little brother Norm Nelson, on the other hand, goes straight to the top of the Class and can sit beside WildDog, for getting it right !

1) 2777 fps was the velocity obtained with the original powder load of 50.7 gr AR2209, jumping Hybrids 0.010"

2) adding 0.8 gr , to make 51.5 gr AR2209, put me back at approx 2825 fps.

I was hoping for only 0.005 to 0.010 for the "nip", but absolutely trust Matt P in that he had to go to 0.040" to get it perfectly round and even .
It just might be that 180 gr VLDs and Hybrids in a 284 Win have a tendency to lap/wear heavily compared to other combinations. I had Phil Jones (Redback) rechamber a Maddco barrel very recently with 1000 shots through it. He cut the whole tenon off, rechambered , then inspected, and redkons it was still very oval in shape. That meant having to "pick the thread up" after putting the reamer in deeper till he found a clean, round finish that I had asked for.
It had shot 180 gr Hybrids jumped 0.015" for it first 1000 rounds.

I might have an idea how it's going to handle Hybrids after this weekend. Then again it IS North Arm OPM and it's highly possible to leave there without having a bloody clue as to how any load went. This is the home of the most unreadable conditions in Queensland, when it's a bad day, and where grown men have been reduced to tears.

Might as well set it back one turn (.062") & no load redevelopment. I never touch mine unless I cut the thread section off & fully refit, The way it looks at the moment they will go to somewhere between 1500 & 2000 rounds before that will be needed . Something to be said for long necks & 40 degree shoulders perhaps, not to mention moderate chamber pressures. .
Keith H.

I might have an idea how it's going to handle Hybrids after this weekend. Then again it IS North Arm OPM and it's highly possible to leave there without having a bloody clue as to how any load went. This is the home of the most unreadable conditions in Queensland, when it's a bad day, and where grown men have been reduced to tears.

On that note , I'm currently at Coolum and it's blowing a beepen gale here from the East ! So hold onto your hats tomorrow !

Tony- have you looked at jamming hybrids yet? I think I told you a few times that my 260 improved shot the 140 vld and 140 hybrids both jammed the same amount, really really well at 1000. Same charge and all.