260 Remington (Lapua brass problem)

J

Jeffreytooker

Guest
I am a 1000 yard shooter from Northern California. I have built a 260 Remington. It is the large action Savage with a Criterion 30" barrel, one inch at muzzle. It was chambered with a PTG 260 Remington reamer by Criterion. Head space is correct. I am loading Lapua 260 Remington brass. This brass was produced in early 2011. The bullet is 142 Sierra MK, primer Wolf LR, Powder H4350 43.5 gr, one grain under max. per Hodgdon manual, online. Pressure is under 58,000 psi. No signs on brass of excessive pressure, with one exception. The exception is the extractor groove. The case head diameter at the bottom of the extractor groove should be .409". After about three firings the extractor groove case head diameter is swelling. It swells enough that I can not get it to fit into the shell holder of my Lee Auto Prime. The Autoprime shell holder has a bit smaller diameter than my number two shell holder for my loading press. Also when seating primers in the rounds with three firings, they some seem to seat too easily. They are not loose yet. I am using Lapua 6 BR Norma brass in another Savage rifle, (same build) and after 12+ firings at much higher pressures this problem does not occur. My conclusion soft brass. Has anyone come across this problem before?

I plan to make ten 260 Remington cases from new (pre blue box) 308 Win Lapua brass and fire them each five times with the same loading as before in the same rifle. If the problem re occurs it is my rifle and not the brass. If the problem does not re occur it is that the original brass was soft.

All advise greatly appreciated.

Jeffrey Tooker
 
I believe that yours is one of the best written question posts that I have ever read. As to the question, I believe that several shooters have observed that large primer, 308 head diameter cases will take less pressure to show expansion, than small primer pocket cases of the same size, probably because the inside of the primer pocket, being of larger diameter, and having more area, gives a greater area for the pressure to act on, and this combines with the smaller amount of brass surrounding the pocket, resisting that pressure, to make it less pressure tolerant. I will be interested in your results.
 
I believe Boyd Allen is right about your question. Many people have a problem and want a solution that agrees with what they think with no work or experimenting on their part.
You are being very analytical in your analysisof the problem, propose a possible experiment to prove your hypothesis, and are working toward a solution.
Is the .308 brass that you are going to use the small primer Lapua that was sold about a year ago?
Keep up the good work and you should have a correct reason for the problem shortly. The solution is a different matter, possibly reforming .308 brass?
 
Brass formed from Lapua 308 Win LP. Ten cases loaded. Will check cases after fire form. The neck is SAAMI (.298) so the loaded cartridge neck (.2964) has enough clearance, for now. It is storming up here. I am about 45 miles South East of Redding Ca. I may get to shoot on Thursday.

Jeffrey
 
Jeffrey,

I had very similar experiences as you did. When testing loads in my .260 long range bench gun with H4350 and RL19 with 140 Amax, the top loads showed expansion in the case web and primer pockets along with a slight ejector mark, flatter primers and more resistance opening bolt lift. I mic'd the cases as they came out of the gun and knew I had passed the ceiling when the case web showed about .0015 to .002 expansion. Duh!

At home on the reloading bench, the cases that had the hot loads in them would go into the shell holder in my press but not in my K&M priming tool that use the Lee case holders. I took a stone to the Lee shell holder (it was about .005 smaller at the extraction groove than my RCBS shell holder) and opened it to take the cases. When I primed these cases, seating pressure was obviously less than with the cases that did not show expansion at the web.

My conclusions: I found and exceeded the safe ceiling in my gun with the various component combinations. The Lee shell holder that I have was made "tight" compared to the other guy's product. My chronograph showed some impressive velocities. Lapua brass behaved predictably for me when I abused it.

Jerry
 
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Sorry, off-topic

Jeffreytooker said:
I am about 45 miles South East of Redding Ca.
Click to expand...
Hmm. Not much there, at least on the Google map. But Google skips things...I use to work just outside Montgomery Creek (about 45 miles North East of Redding), and you've really got to blow the map size up to find it. Anyway, for a hot time, we'd go into Burney... This in 1960-63...
 
Charles:

My wife's aunt lives in Burney. It is still a mill town and doing OK. The mill is still open. Lots of mills have closed here in the North North of the state.

Jeffrey
 
Jerry:

I agree with all of your conclusions. However the load I am using is 142 SMK H4350 43.5. That is one grain under max by Hodgdon online manual. Pressure is under 58K. There should be no appreciable case expansion at this pressure. I am running Lapua 6 BR (N) cases at 60+ and these problems do not occur.

In reading online, the Lapua rep acknowledged that Lapua had some problems with early production 308 Win SP. I think they may have had a bit of soft brass. I will run my tests and see what happens.

Jeffrey
 
Hi Jeffrey

Is the 58000 psi measured or what's in Hodgdon's online manual?

SAAMI lists the extractor groove diameter as 0.409". How did you measure it? With a caliper? I'd measure the case head diameter 0.200" from the base of the cartridge with a micrometer instead. It shouldn't be more than 0.471" but it could be as much as 0.473" and still be within SAAMI specs. You say there's no signs of excessive pressure so I assume the brass doesn't show a bulge there. A bulge would suggest a larger chamber: smaller cartridge dimension relationship.

Here's a link to the SAAMI maximum cartridge/minimum chamber dimensions.
http://saami.org/PubResources/CC_Drawings/Rifle/260 Remington.pdf
The PTG chamber print and your cartridges will tell you more.

My 22-243 Winchester reamer print is for Lapua 243 brass and has a base diameter right at 0.471" for a minimum chamber dimension and close fit for the brass, but unfired brass can be as small as 0.462" and still be in specification. Brass like this will show a noticeable bulge on the case head after firing. Sizing it back down will rapidly lead to case head separation - not good. Neck sizing will prolong its life, but a better chamber:cartridge fit is ideal.

It does sound like you're having pressure issues. Hopefully someone else can be of more assistance.

Regards
Ben
 
Jeffreytooker said:
Jerry:

I agree with all of your conclusions. However the load I am using is 142 SMK H4350 43.5. That is one grain under max by Hodgdon online manual. Pressure is under 58K. There should be no appreciable case expansion at this pressure. I am running Lapua 6 BR (N) cases at 60+ and these problems do not occur.

In reading online, the Lapua rep acknowledged that Lapua had some problems with early production 308 Win SP. I think they may have had a bit of soft brass. I will run my tests and see what happens.

Jeffrey
Click to expand...

Jeffrey,

I run the 142 SMK's with H4350 as well and my gun likes 44 grs. Have run them with 44.5 grs. and not seen any issues with head expansion of the brass. Just slightly flattened primers and slight ejector marks. Having said that, just from my experience with this gun, I wouldn't run it hotter than 44.5 grs. because it seems to be approaching the hairy edge. Makes me wonder about some of the spectacular claims of powder charges and velocities some fellows report in online forums. Sheesh!

I purchased my 1st 100 count box of .260 Lapua brass in December of 2011, but do not know when they were manufactured, so no help there. Sorry

Good luck with your experiment and I hope you get usable results.

Jerry
 
Ben in Oz:

<Is the 58000 psi measured or what's in Hodgdon's online manual?>

Yes Hodgdon manual . Quickload actually 57801 psi. with the bullet seated for 3.010 cartridge length. I have found Quickload to be quite reliable.



<<Here's a link to the SAAMI maximum cartridge/minimum chamber dimensions.
http://saami.org/PubResources/CC_Drawings/Rifle/260 Remington.pdf
The PTG chamber print and your cartridges will tell you more.>>

I have on file PTG reamer PDF's for the 260 Rem SAAMI and "Match" reamers. Per your suggestion I reviewed both. Besides the .298 neck for the SAAMI, as opposed to the .294 neck for the "Match" there is one other difference. That is that the case head dimension for the SAAMI is .4738 and the case head dimension for the "Match" is .4723. This is a thou and a half larger for the SAAMI. The new Lapua 260 brass is .4691 at the case head. That is .0047 for expansion. That is an awful lot. So Lapua 260 Rem brass is made for match chambers not SAAMI. The problem I have is too big a chamber, which allows the case head expansion that I am having. It also accounts for the loosening primer pockets. It is not a pressure problem, and most reasonably soft brass. I have found that my 260 trim die, sizes the body (case head dimension) just a touch. This will keep from sizing the brass too much. I will quit using my match body die because it sizes too much. As far as the Lee Auto Prime No. 2 shell holder, a No 3 three works well enough. The case necks are also made for a match neck. I will try making brass from 308 Win (Lapua) brass once I shoot out this brass. Thicker necks. That should correct the neck problem. In the long run, getting the next barrel chambered with a 260 match reamer will fix the problem.

Conclusion: There is nothing wrong with Lapua 260 Rem brass. It just does not fit a SAAMI chamber well and will be short lived. Use a match chamber and all is well. Making brass from 308 Win may still result in loose primer pockets.

Once again thanks for your help.

Jeffrey
 
Jeffrey,

At least one guy, alinwa (Al, in Washington), would find your chamber just to his liking. He has apparently developed a method for using larger chambers and higher (but safe) pressures. I never quite figured out all the details, but I do not doubt that he gets it to work. You might try PM'ing him -- he hasn't posted in a while -- and see what his advice is.

The other thing I know is to work-harden the cases with 45,000-50,000 psi loads 2-3 times before using the 55K pressures. Or, if you have access to a punch press, make some dies to work harden them.

Too, it may just be a particular run of Lapua cases. I'm sure they are within spec, but just how much annealing is done & how it is controlled at the case head can be a factor. If your 1,000 yard sport (say, BR rather than HighPower) doesn't put too high a demand on the number of cases you have to prep, you might be able to work harden them & get get good life.

Or maybe Al will have a good solution.
 
Hi Jeffrey, you may just consider, trying the Nosler custom .260 brass. I have used it in all my improved and standard .260 chambers, and the brass is top end in my opinion. Hope the TSA gang is doing well! Ron Tilley
 
hey tillroot1 you have the specs of the nosler custom .260 brass. I have the same setup as Jeffrey....... Just put gun together this week....
 
Crashem, I dont have any specs, but its gotta be standard, maybe give Nosler a call, I am sure they can help. good luck! Ron Tilley
crashem said:
hey tillroot1 you have the specs of the nosler custom .260 brass. I have the same setup as Jeffrey....... Just put gun together this week....
Click to expand...
 
I looked at the Hodgdon site and it didnt list a barrel length for the test gun. Many of the tests in my reloading manuals are done with a hunting length barrel 22-24 inches. Could the 30 inch barrel on your gun and the slowish 4350 powder be making more pressure than the test gun cause the longer barrel is letting it burn longer and making more pressure?
 
Thinking of 260 Rem.

tillroot1 said:
Crashem, I dont have any specs, but its gotta be standard, maybe give Nosler a call, I am sure they can help. good luck! Ron Tilley
Click to expand...

I see you all shoot 260 Remington. I am very serious about sending in my Savage 110 and having Savage put a 26" SS barrel on it with a 1/8 twist. I would like to try a little long range shooting.

Any advise?

Is this a good choice? It sure looks like a good choice to me but I have never done this type of shooting. Hunted Elk and Mule Deer all my life in Idaho.

Are there other options I should consider.

Would also like to shoot whistle pigs at long distance. Maybe even trophy mule deer.

Any Thoughts?
 
The original post was made because the poster couldn't achieve the pressure he thought he should......

I would build a 6.5X47 Lapua instead.

There :)

You asked for thoughts....

al
 
Jeffreytooker said:
However the load I am using is 142 SMK H4350 43.5. That is one grain under max by Hodgdon online manual. Pressure is under 58K.
Click to expand...

You are putting way too much faith in an online manual. Every rifle chamber is different, maximum loads need to be approached carefully by working up from lighter loads. I have about 8 different barrels that were all chambered by same reamer that all shoot the same load fine, and a 9th barrel that requires a half grain less powder to even be safe.
 
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