Good Forum to Ask a Question About Jacketed Bullets
- Thread starter Reed
- Start date
Reed
Active Member
That's a good clue. Freebullet kind of touched on the longer bullet theme as well. Maybe I should quit fooling around w/ 150 gr bullets for that gun.
quicksylver
Well-Known Member
The original 1906 - 30-06 military round used a 150 gr flat based bullet....
quicksylver
Well-Known Member
Did I hear some one mention go and no go gauges being tried..?
fiver
Well-Known Member
right,,, the original mil round was 150.
but I'm thinking this one doesn't have that original chambering cut into it.
the thread has kind of wandered here and there some, but figuring out the original reason, or for what purpose the chamber was cut for, would be a huge help.
I am imagining someone was using this rifle for some type of match shooting and had a 'pet load' or a certain batch of cheap milsurp ammo [or bullets] in mind.
but I'm thinking this one doesn't have that original chambering cut into it.
the thread has kind of wandered here and there some, but figuring out the original reason, or for what purpose the chamber was cut for, would be a huge help.
I am imagining someone was using this rifle for some type of match shooting and had a 'pet load' or a certain batch of cheap milsurp ammo [or bullets] in mind.
yodogsandman
Well-Known Member
My book says the suggested trim to length is 2.484" and max length is 2.494". So, yes your cases are running into the throat and the case mouth is being squished.
RBHarter
West Central AR
Have I ever told you about the 7mm wildcat GEW 98 ?
The bbl slugged 277x284 . A fired case would take .301 .
I actually slipped a 301 sized 301618 in the neck of a fired case . There was significant throat erosion for about 1.2" in front of the chamber . To save the bbl I could cut the whole shank off and probably be ok with a 280AI or I could set it back the full 1.2 and do a 7×57 AI for a SR I have around .
The point being that in that rifle the neck grew with the throat erosion to a point that a sized empty 30-06 could be could be chambered without more than a firm hand and even a 7mm-168 with a 278 nose was swinging in the breeze with the top lube groove used as a crimp groove .
The bbl slugged 277x284 . A fired case would take .301 .
I actually slipped a 301 sized 301618 in the neck of a fired case . There was significant throat erosion for about 1.2" in front of the chamber . To save the bbl I could cut the whole shank off and probably be ok with a 280AI or I could set it back the full 1.2 and do a 7×57 AI for a SR I have around .
The point being that in that rifle the neck grew with the throat erosion to a point that a sized empty 30-06 could be could be chambered without more than a firm hand and even a 7mm-168 with a 278 nose was swinging in the breeze with the top lube groove used as a crimp groove .
quicksylver
Well-Known Member
Yep ...it's getting to sound like my Remington 03 ...bright shinny bore ...looks fantastic...but I can take a 314299 with a .304 nose, sized .311 and seat it in a case so only about an 1/8" is in the case and finger insert it in the chamber..no throat left....fortunately I shoot cast so sizing to .312 and seating it out a respectable distance brings the old girl back to her former glory...I got it because the second owner couldn't get it to shoot jacketed bullets for beans...
Definitely sounds like a pound cast is in order..or for that matter a chamber cast..
Definitely sounds like a pound cast is in order..or for that matter a chamber cast..
Ian
Notorious member
Good catch there. .270 brass Reed's using is a good bit longer than '06. A pound cast would tell all.
yodogsandman
Well-Known Member
Is this to get the bullet closer to the lands or to get more of the bullet in the case mouth? What's the plan? Either way, the easy way is to get a longer (heavier) bullet. If you just have to stick with a 150gr, try different bullets until one works.
Having too long of case necks could get you in trouble fast. If the case mouth pinches the bullet when fired, pressures spike and things blow up. With thicker commercial 30-06 or military 30-06 case necks you might not have been so lucky.
Same goes for jacketed bullets that cram against the lands. It might be a favorite trick of some bench rest shooters but, they start load testing at very low minimum charges and carefully work the charge up in miniscule increments. They aren't looking for the highest velocity and only maximum accuracy counts for them. Do this at the upper end of the powder charge range and BOOM. Jacketed bullets need to have some space to run up to the lands before max gas pressures are reached. The books preach .050" off the lands to start and to work away from the lands to find an accuracy node. Anything less and you should be very careful and only work near the starting loads.
Reed
Active Member
Is this to get the bullet closer to the lands or to get more of the bullet in the case mouth? What's the plan? Either way, the easy way is to get a longer (heavier) bullet. If you just have to stick with a 150gr, try different bullets until one works.
Having too long of case necks could get you in trouble fast. If the case mouth pinches the bullet when fired, pressures spike and things blow up. With thicker commercial 30-06 or military 30-06 case necks you might not have been so lucky.
Same goes for jacketed bullets that cram against the lands. It might be a favorite trick of some bench rest shooters but, they start load testing at very low minimum charges and carefully work the charge up in miniscule increments. They aren't looking for the highest velocity and only maximum accuracy counts for them. Do this at the upper end of the powder charge range and BOOM. Jacketed bullets need to have some space to run up to the lands before max gas pressures are reached. The books preach .050" off the lands to start and to work away from the lands to find an accuracy node. Anything less and you should be very careful and only work near the starting loads.
"The plan" is as you suspect: to get the bullet closer to the lands. Depending on the ogive, some 150 gr bullets I've tried don't find the lands until they're almost falling out of the case. A few posts back I mentioned I wouldn't be loading to that case length again, but then, I'm not so sure that loading strictly to SAAMI case length is the answer for this rifle. Heavier bullets is a good suggestion, and it might be the direction I end up going.
However, this chamber/throat area is long, and there's room for longer brass. Maybe not quite as long as mine ended up, though. As I said a few posts back, had I not allowed the cases to grow so long by my head spacing flub, my case mouths wouldn't be measuring as small as they were (.310). I did ream the case necks, so thick brass wasn't a consideration in this instance. That's not to say that I would always remember to ream necks, so your point about thicker brass is well taken. Did you really mean .050" off the lands or .005" off the lands? I loaded these .005" off. I noticed a Sinclair article recommends starting at .010 (http://www.sinclairintl.com/GunTech/Determining-Bullet-Seating-Depth-/detail.htm?lid=16131), a Nosler article mentions .015 in their example (https://www.nosler.com/blog/news-and-articles/2013/6/4/beyond-the-basics-developing-your-own-loads). A Berger article mentions that the best seating depth is very near or just touching the lands, but also states that the best accuracy in some rifles has been found with the bullet .100" away (http://www.bergerbullets.com/effect...coal-and-cartridge-base-to-ogive-cbto-part-1/). Wow.
You're right about the charge. I should have started at the front of the range instead of the middle just to be safer. (Lyman 48 & 49, 2002 & 2008, 48.0-53.0, 2695-3012, 36,000-49,600 cup). Velocity was about in the middle of Lyman's data for my 50.0 gr load (2880). If there had been excess pressure, wouldn't that have shown as considerably higher velocities?
I do appreciate everyone's comments and cautions. Loading almost exclusively cast has shielded me from many of the nuances of loading jacketed bullets. I've gained some perspective. With that said, (and here's where some may shake their heads) I am still going to experiment with slightly longer cases than 2.494. I won't be revisiting my recent case length, however. I'll also back the charge down to the starting suggestion. Maybe go buy some 4350 while I'm at it.
Ian
Notorious member
There is no magic universal number for seating jax off the lands. The only universal thing is that the closer they are to touching, the higher the initial chamber pressure will be. Never a good idea to combine warm loads with contact. I use .010" as a starting point with all my jax, and after a few good test drives will tweak that a bit if I think it needs it, just to see what happens.
F
freebullet
Guest
I usually find 0.020 off is a sweet spot in autoloaders with jax. Sometimes closer or farther works to but, one thing is certain- ya don't wanna be cramming Jax in the throat with long brass while touching off heavy charges. No no.
If you made your pound cast with a trimmed case you should be able to measure it to see how long your rifle can handle the cases. The loads I mentioned on the other page were with trimmed brass. They were seated in the cannalure(which put them roughly 0.035 off) on the 150 & about 0.020 off for the smk's.
If you trim the brass to an acceptable length, load them the right length, & dial the charge back to around what I listed, you might could find some success with what you already have. We did.
If you made your pound cast with a trimmed case you should be able to measure it to see how long your rifle can handle the cases. The loads I mentioned on the other page were with trimmed brass. They were seated in the cannalure(which put them roughly 0.035 off) on the 150 & about 0.020 off for the smk's.
If you trim the brass to an acceptable length, load them the right length, & dial the charge back to around what I listed, you might could find some success with what you already have. We did.
fiver
Well-Known Member
freebullet beat me to it.
a pound slug is invaluable.
I know almost all of my rifles have chamber necks cut longer than saami length.
I don't get over panicked about jump.
some rifles do well with a short jump, but sometimes you ain't got that option.
in that case I go the other way.
I have found very, very good accuracy with jumps so long I could measure them with a ruler.
now..... there are cheats and the cast world provides them, a successful cast load needs fitment, fitment of the nose and of the body.
when you get a pound cast in hand you will know the exact shape and diameter your dealing with.
mimic that shape with your bullets nose shape and I bet your accuracy will improve even with a 1/2" jump.
one more cheat that can get you accuracy in a rifle that is fighting you all the way is to take another page from the cast world 310-311 bullets can be used in a 308 rifle if the throat is appropriately shaped.
you'd be taking a page from SAVAGE's play book with their 303 round.
it was nothing more than a 190gr 30-30 with a 311 bullet in a 308 barrel to bump the pressures a bit to gain that extra 50 fps in velocity.
yep advertising 'speed' sold 100 years ago too.
a pound slug is invaluable.
I know almost all of my rifles have chamber necks cut longer than saami length.
I don't get over panicked about jump.
some rifles do well with a short jump, but sometimes you ain't got that option.
in that case I go the other way.
I have found very, very good accuracy with jumps so long I could measure them with a ruler.
now..... there are cheats and the cast world provides them, a successful cast load needs fitment, fitment of the nose and of the body.
when you get a pound cast in hand you will know the exact shape and diameter your dealing with.
mimic that shape with your bullets nose shape and I bet your accuracy will improve even with a 1/2" jump.
one more cheat that can get you accuracy in a rifle that is fighting you all the way is to take another page from the cast world 310-311 bullets can be used in a 308 rifle if the throat is appropriately shaped.
you'd be taking a page from SAVAGE's play book with their 303 round.
it was nothing more than a 190gr 30-30 with a 311 bullet in a 308 barrel to bump the pressures a bit to gain that extra 50 fps in velocity.
yep advertising 'speed' sold 100 years ago too.