I shoot a 330 Dakota which is exceedingly accurate and my primary big game rifle. For those not familiar with the round, it’s a 404 based short magnum with minimal body taper. Brass is very expensive but I have had great longevity so far by keeping velocities reasonable and annealing. I am at 6-9 reloads on the original 40 pieces of brass that I have and have developed a problem that is giving me fits.

Rounds are becoming increasingly difficult to chamber. Re-sized brass chambers with no difficulty and I have adjusted my sizer to where it is touching the shell holder. Cases have been trimmed to specs. I smoked several of the rounds last night and I am getting contact at both the outside of the shoulder (not the forward/sloped surface) and where the shoulder meets the neck. The shoulder mics fine and it would be strange that this dimension would change as a bullet is seated. I suspect that I am getting brass flow to the base of the neck.

First, is this plausible, especially with such a straight walled case? If so, what are my options? I do not currently own an outside neck turning tool but would this solve the problem? Can one get all the way to the junction of neck and shoulder with such a tool? How do you know how much brass to take?

Thank you for your help with this.

I'm having a sim. problem w/ my .260ai & some case that are on their9-10 firings. I was going to try neck turning, I'll let you know if it works. BTW, I have a 7mmDakota. I always though Rem./WW kind of missed the boat when they brought out their WSM & RUMs. The Dakota carts. offer a lot of perf. in a std. action.

try filling the case with blasto #5 instead of blasto #2 should only decrease the velocity by 4000 FPS or so

You may have to bump the shoulder back more than the die will allow.

The die may be long and your chamber short.

A potential test (if you dare with expensive brass) would be to take a dowel and hammer the case a few thous farter than the it's sized after the shellholder bottoms.

If this is the problem then the solution would be to chuck the die up in the lathe and turn a few thous off.

I had this trouble with a 7.65 x 53 sizing die.

I had a similiar problem on a 7STW I built. But mine started after 2-3 loadings. Unlike you I was loading to the max. LOL I also expect I had the headspace a touch long. Didn't have a lathe but took a file to the top of a shell holder. Did take much. Just bumps the shoulder back enough to allow it to chamber.

Oops, I duplicated ramrod's suggestion

quote:

Originally posted by snowcat:

Rounds are becoming increasingly difficult to chamber. Re-sized brass chambers with no difficulty and I have adjusted my sizer to where it is touching the shell holder. Cases have been trimmed to specs. I smoked several of the rounds last night and I am getting contact at both the outside of the shoulder (not the forward/sloped surface) and where the shoulder meets the neck. The shoulder mics fine and it would be strange that this dimension would change as a bullet is seated. I suspect that I am getting brass flow to the base of the neck.

First, is this plausible, especially with such a straight walled case? If so, what are my options? I do not currently own an outside neck turning tool but would this solve the problem? Can one get all the way to the junction of neck and shoulder with such a tool? How do you know how much brass to take?

Thank you for your help with this.

Explain what the problem is again. You say resized brass chambers with no problem. Does the chambering problem happen after seating a bullet?

If the resized brass chambers then why would you think you have brass flow to the base of the neck? If you had brass flow to the neck it would show up after resizing whether a bullet was seated or not and cause hard chambering. If the cartridge is hard to chamber after bullet seating then maybe it is seated out too far and contacting the lands.

Don't get it.


Without guns we are subjects or victims, with guns we are citizens

Did you ever consider that the necks might bee getting thick after that many fireings. If a sized case chambers ok but not with a bullet seated that what I would check. Obviously you have reloaded this rifle to know how long to seat the bullets without interfearing with the lands.
Lyle

I apologize if I wasn't clear in my initial post--I think that the case neck (especially where it meets the shoulder may be getting thick as a result of brass flow. I thought of the possibility of shaving the die but as a resized case prior to seating a bullet chambers fine, I think that the case is being sized properly but when the bullet is seated the dia of the neck may be too great. My calipers are apparently not sensitive to detect the difference b/t wht dia of a tight and normal case however. I usually partially FL size--whould this encourage thickening of the neck at the shoulder/neck junction? The problem seems vary in severity proportional to the number of times the case has been reloaded. BTW, it is not the OAL as I both started with a Stoney Point gauge and progressively shortened the OAL on a tight case to no avail.

I really think the neck is thickening--can one of the sinclair outside turners get all the way to the shoulder? What is the ideal thickness. Does brass annealing exacerbate the problem of brass flow?

Thanks a million for all the input guys.


Butchbloc:
225 Accubond at 2925 behind 81g RL22, 3.495 COL, Norma brass. Primer pockets have stayed tight for > 9 loadings. Load shoots an honest 0.75/5 shot (slow) string and does not exhibit signs of excess pressure. Your point?

your brass needs replaced
you have woked it to much.

BEFORE you go doing any neck turning, take your brass with and without seated bullet to a machinist and have him accurately do the measurements. Have him use a tubing micrometer and measure the inside of the neck of your brass both at the mouth and at the shoulder.
Find out what your problem actually is before you attempt any solutions.

Don't forget that one of your neck turning options is to turn the INSIDE of the neck to get rid of any possible donuts.

I would also do a chamber cast to get a reasonably accurate idea of the actual dimensions of your chamber. It may be too tight in the neck. Just remember that the cerrosafe or other casting material shrinks a bit and also will change dimesion over time and due to temperature.

You might want to anneal the forward portion of your brass. The Dakota brass is very thick and often too hard in this area. When sized it tends to spring back. Regards, Bill.

to where the loaded case is hard to chamber you have a dangerous condition. Best solve the problem before firing.
Good luck!

I shoot both a 330 and a 300 Dakota. No problems with the brass. I have used Mast/Dakota and Norma/Dakota along with reformed brass from Rem 300/338 Ultra Mag, RWS 404 and Bell 404. The thick neck issue might be a possibility, measure your loaded rounds, and compare your dim's with your reamer dim's(assuming it is a custom chamber), if it is factory compare to specs. I don't turn my necks and have had no problems, amongst three of us shooting Dakotas some of the original Mast brass has been loaded ten times, pockets are now loose but necks are good. The Ultra Mag brass is holding up well also, the brass is cheap but you will need a neck rem die and that is expensive but does an excellent job and pays itself off in quick order with the money you will save. You will need a stout press to reforme this brass, nothing less than a RCBS Rockchucker in size.
bigbull

I'd say that if you're getting that much brass flow that you're at risk of a case head separation... mild loads don't always lead to good case life...

Thanks to all for the replies. I have over 120 pcs of the MAST brass (which is thicker, has less capacity) which I will experiment with. I may turn a neck or two just to see whether that is actiall the problem--anyone have any experience with the RCBS inside/outside turning device?

Bigbull--what was your experience moving between the Mast and Norma brass? Is it worth the additional investment in the thinner Norma product if I already have the Mast in your opinion?

Can someone give me a range of neck wall thicknesses to expect so that when I get the bad brass mic'd I can know where I stand?

Is there a way to gauge whether case head separation is imminent? In belted rounds you can usually feel a notch right above the belt....

Thanks again!

quote:

Is there a way to gauge whether case head separation is imminent? In belted rounds you can usually feel a notch right above the belt....

Same way with a non-belted case, in roughly the same area of the case. Section a case sometime and see for yourself why that is - internal taper is similar, belt or no belt, and the seperation happens at the end of the taper.

Thats what happens when brass has been worked too much, its dead...You have had enough firings, now buy some new brass...When you get new brass size it until you get a crush fit on your shoulder, but many time it will just slop in then when you fire it, it fireforms itself to your chamber...My suggestion is if the new brass slops in when new, it should be firefromed with pistol powder and cormeal or whatever...then brass will last if properly taken care of. shooting a full load the first time is practiced a lot, but it is hard on brass and will shorten case life dramatically...

With any hi intensity caliber I expect about 6 max loads then I get new brass...

You may have a ring on the inside of the shoulder junction and they can be cut out with an inside neck reamer...or if you are handy with a thin bladed pocket knife.

I found the problem. I cut several cases in half last night and, like Ray said, I have a ring on the inside of the neck right at where it meets the shoulder. When the case is sized it chambers fine but when a bullet is seated this ring forces the neck to expand too much and prevents smooth chambering. The looks fine over the rest of the case, no thin spots near the web, etc. I think that with inside neck reaming the brass would be fine. A note, this problem developed after I annealed the case neck which may have encouraged forming of the ring.

What's the easiest tool to use to inside ream case necks. I have a Trim Pro and would like to use the inside reamer pilot RCBS makes but don't know if the pilot shaft is the same diameter as the Trim Pro pilots. Anyone know? Thanks!

quote:

Originally posted by snowcat:

Bigbull--what was your experience moving between the Mast and Norma brass? Is it worth the additional investment in the thinner Norma product if I already have the Mast in your opinion?

Is there a way to gauge whether case head separation is imminent? In belted rounds you can usually feel a notch right above the belt....

Thanks again!

My experience with the mast is it is good brass, you can turn the necks only enough to remove high spots and that's it. Proper sizing of your brass will increase its life, in other words don't oversize! A good fireform is also helpfull in forming your cases, I believe the only way to properly fireform is to seat the bullet so that there is no forward case movement upon firing pin impact otherwise you cases will be driven forward and expand back upon firing this is exactly what you don't wan to happen!

The iminent rupture will occur if you oversize your cases, the bright ring around the base of the shell is only present when there is a large discepancie in 1. case chamber diameter 2. excessive headspace
I should also mention that I use a RCBS inside neck reamer for my cases and find it is excellent in reducing case neck thickness especially when forming brass from Rem Ultra Mag to Dakota ! Yes this is doable!

bigbull