Fireforming cases - failure rate???

[memilanuk]

Hello,

Well, I finally got around to taking that next step... a round that is 'improved' and thus needs fire-forming. I decided the 6 Dasher was a good choice, and got a barrel chambered up on a Savage RBLP Target Action, in a SSS Dog Tracker stock.

I have 200 pcs of virgin Lapua 6mm BR brass sitting on the shelf. For this first venture into fire-forming, I thought I'd use 40 pcs of once-fired brass from factory Lapua ammo. Cleaned it up, did all the usual prep,F/L size, trim/chamfer/debur, uniform flash hole and primer pocket), then replaced the decapping pin and carbide ball on the Redding Type 'S' F/L die w/ a .25 cal tapered expander plug to create the false shoulder. Following that I necked it back down using a .269 bushing... and had to re-do that using a .265 bushing due to the spring back,bullets were dropping in the case mouth, having sprang back to .243-.244 ID). Primed the cases w/ BR-4 primers, charged 'em w/ 32.0gr IMR4895, and seated some left-over Lapua 105gr Scenars to about +10 jam into the lands, and headed to the range.

Well... the problem in all this is simple... out of 40 pcs of brass I took to the range, 20%,8 cases) failed. As in: a hole or split just above the new fire-formed shoulder. Most were pretty small, maybe 1/16"-1/8" long. A couple were almost 1/4" long, and went below the shoulder as well.

Somehow I didn't think 20% failure rate was quite normal...?

The brass was 1x fired already... I wouldn't think that it'd be work-hardened enough to be the cause of splitting. The load was a bit stout... definitely gave a sharp shoulder on all the fired rounds.

What else should I be looking for as a potential culprit? I really don't want to be giving up 40 of my brandy new cases in the boxes right off the bat!!! :cry:

TIA,

Monte

 

[Magical_Merlin]

Monte, I think you should contact Chris Long. I believe he fire forms his 6 dasher with the cornmeal method.

 

[brfun]

I am sure with the number of guys shooting dashers here they will have a lot more for you then I. But first I agree with you the load is on the warm side but I don't think that is you problem. I do believe that it is the once fired brass. I have only formed 100 for my dasher and I also went the false shoulder method. Out of 100 pieces I lost 2 that match your description with new brass. I fire formed mine with 30 grains of Varget, cci450 and 95's. If no one else has any better ideas I would say try a few new pieces of brass and see how it goes.
Good Luck
Brian

 

[memilanuk]

Michael,

He may use cornmeal for other cartridges... but if you look at his 6 Dasher page, it clearly shows the false-shoulder cases side by side w/ the original 6mm BR and the formed 6 Dasher. He used those same fire-forming loads the first time he shot here @ East Wenatchee.

Normally I would bounce this off of him first, but I think he's been kind of busy lately...

Monte

 

[Magical_Merlin]

Gotcha, I know he has a lot of experience with the dasher. Good luck.

 

[JERRYHM]

Monte,
I have fire formed more than 1000 cases for the Dasher, the first 100 were done with the cornmeal method. It made a lot of noise and stunk. After I found out how good they shot fire forming, I fire formed in matches. I have lost about 3 or 4 cases using 33 grains of Varget with a Sierra 107.

6BR IMP Broughton Barrel --- 25 JULY 2005

8 ½ “ Bat action Dual port
Broughton 6MM 8 Twist 5C 32” barrel
7.97 Contour .2430” X .2368”
D&B stock, NF 8-32X scope

Reamer used is the 6BR IMP UBL
Lapua 6BR Brass CCI-BR primers, Max L=1.560”, Trim to 1.550”
Neck dia. Sized = 0.266”, loaded = 0.268”, fired = 0.2715”

The OAL to touch the lands is 2.423” for the Sierra 107 grains.
The OAL to touch the lands is 2.430” for the Sierra 115 grains.
100 yard testing, elev. = 200’, temp = 90, humidity = 15%

Load Testing, fire forming
Varget 33.0 gr. MV = 3000 fps, ES = 19, SD = 09, 5 shot group = 0.160”

 

[flatlander]

Monte,
I've fireformed over 1200 Dasher cases in four barrels using more-or-less full-power loads with new Lapua using the false shoulder method, and my loss rate is around 1%. As Jerry says, fireforming accuracy is far too good to mess around with cornmeal, or just blasting bullets into the backstop. I started forming with 33grs. of Varget and moly'd S107MKs, but it seems that the failure rate is a little less with 32.5grs. My first cleans at 600 were shot with fireforming loads in a Dasher - given the price of bullets today, there's a lot to be said for a cartridge that makes good use of the components used while fireforming.

 

[rcw3]

Monte
I am not saying this is the case for you, but I purchased some 6BR Lapua brass a while back and when I shot some it in my 6BR bolt gun, right away I lost a number of cases to length wise splits in the neck/shoulder area. When I looked at some of the new brass through a 12x jewler's loupe, it appeared that about 15% or so of the new cases appeared to be predisposed to split this way,under magnification, some of the brass shows length wise lines that appear to be weakness areas), and I can imagine if you did a fire form with that brass you would have the result you are describing. Your loss rate on fire forming may have less to do with how you are doing it and more to do with the batch of brass you have.

Robert Whitley

 

[memilanuk]

Hmmm... I'll have to give the Varget load a try. Lord knows I've got enough of the stuff around here :thumb:

Hopefully the problem is just that batch of brass...

 

[flatlander]

Monte,
Give some consideration to what Robert said - a little over a year ago, I found a couple of new Lapua BR cases with a slight crease in the neck area that split there when fireformed. In my case, the defect was fairly obvious, in that it did not require much, if any, magnification to see. Sounds like what Robert is talking about may be less obvious, but whatever the case, I'd like to hear what Lapua has to say about it. Personally, I'm not too keen on the idea of paying a premium price for cases with defects. Obviously, many of us have become very spoiled by Lapua's QC in the past, and I doubt any of us are going to be very tolorent of anything less than near-perfection when we dig into the gold boxes,that are priced accordingly) for brass.

 

[memilanuk]

Dennis,

My 'last' batch of Lapua 6 BR brass surprised me w/ one or two showing splits in the neck - one after one firing, another after two. Then some 6.5-284 brass w/ over 2 thou runout in the neck walls. Now this. I'm definitely starting to eye Lapua brass w/ question as to whether they're worth the premium if this is the best they can do for $60-85/100...

I did get ahold of Chris Long,techshooter); he seemed to think that the need to size the neck down again with an extra small bushing due to spring back pointed to brass that was already work-hardened, despite being only 1x fired. Otherwise he gets about 1-2% failure like most everybody else reports. I may go ahead and anneal the necks of the new brass after I do all the prep and forming work as an extra 'insurance' policy.

Monte

 

[flatlander]

Monte,
And to think - I was griping when Lapua BR brass was $39/100! I recently paid over $.80 apiece for some RWS 6.5x55 brass because one of my 1000yd. BR buds tells me the RWS stuff is very good, and nearly indestructible. I've just finished chambering a Bartlein hvy. Palma blank for 6.5x55 Ackley Imp. and wanted something better than the Lapua I've been using. Too bad RWS doesn't make 6BR brass,or maybe they do, and no one imports it?). By-and-large though, I've been very pleased with Lapua quality, certainly in 6BR & 6.5x47.