I was shooting my gun and noticed flattened primers, but decided to shoot another and.....

[long range newbie]

Well I was shooting my 260 today and was trying to sight it in but noticed scope was crooked, after but then I noticed flattened primers on the loads with 38.4gr of imr 4831, then I shot one more then it blew a primer and a hole was in the side of the primer pocket.? Is that bad? please help it says max load for 140gr match target was 41.0 grs and I'm 2.6grs under

 

[6.5x47]

Huh? Looking at the Hodgdon site, they don't give a minimum charge, but a 44 gr max for the 140 Partition. Looking at the Loaddata.com site I can find one charge that goes as low as 37.5 for the 140 A-Max. Any 4831 is a slow enough powder that you have to be careful you don't go below the minimum otherwise one can get a kaboom.

Side of the primer pocket? That doesn't sound normal.

I'm not sure.

Alan

 

[oglejust]

u sure ur scale is correct?

 

[long range newbie]

yes I just got the book

 

[long range newbie]

In the berger book It says maximum 41.0 grains but I don't remember the minimum but the primers were flattened at almost 3grs below the maximum? that seems weird I told my dad that I'm gonna pull the bullets on these he said just shoot it one more time and then the primer blew.

 

[Captain Kirk]

Verify charge weight with another scale. What case are you using? Are you seating your bullets into the lands? Something is either causing a pressure spike (ie carbon ring, bullets into lands, etc) or your charge is higher than you think.

 

[long range newbie]

bullets are .01 of the lands, whats a carbon ring? rem brass necked down 7-08.

 

[Dan Newberry]

Are you shooting a Savage? I ask because they generally have short throats (lands are very close) and pressures advance quickly. They'll get high velocity with a lower charge than other makes of rifles (not including customs, of course).

If the rifle is a Savage, let me know... there's some things you'll need to check following that primer puke.

IMR 4831 is not particularly temperature insensitive. If you developed the load when it was cooler, and now that hot weather is getting here, it could have simply gone over the top. Flat primers which fill level to the case head are a bad sign, and you need to stop shooting as soon as you see that. Mildly flattened primers (where you can still see a good groove round the primer edge) are not necessarily a bad thing--but I'd rather not have that either, especially with the price of brass these days.

Dan

 

[haroldwilson]

What is the OAL of the necked down brass?

How did you determine bullet was .010 off the lands?

Also, why neck down brass? There is good .260 brass available.

 

[RADcustom]

Are you sure you have enough clearance in the neck of your chamber?

If you are necking down brass, the neck could be thick.

 

[Captain Kirk]

A carbon ring is when carbon builds up right in front of the chamber, it can cause some issues (mainly accuracy) but can spike pressures. I agree with the 2 posters above, no need to size down brass when there is soo much quality brass available for the 260, it may be part of your issue.

 

[long range newbie]

had measured it with the hornady thread on thingy and I don't have a 308 or 7-08 any more so thought I would put once fired brass to use

 

[long range newbie]

Its a custom barrel made by a local barrel smith. rem 700 sa, it was like 70-80 degrees today but up in the mountains so it was cool, but I do have 40 260 brass. I'm going to try that and today I had a fun time since I dropped my calipers in my lap and it stabbed me in the leg yay.... The hotest day in oregon was a long time ago and the most of the hotest days are probably like 97. My action (I think) is not trued I will ask my gunsmith to do so if he didn't already.

 

[Sargesniper]

Are you throwing charges or weighing them? You seem to have a malfunction in your process. Next time, don't do as Dad says. Use common sense when primers flatten. That is an indication that something is headed your way that is very unpleasant as you found out. Next time???????????. Be careful. ......SEMPER FI!.

 

[long range newbie]

yeah I use one of those rcbs dispensers where you type in the charge and press dispense and it weighs it until at the amount wanted. I don't want my gun blowing up on me. I also measure every bullet, and if its over .1 grain I put it back in and redo it. If the bullet is .0025 over I pull it out and redo it (I don't have my micrometer seater yet) I measured my lands a few times. I do like to take pride in my work (if it works out like I want it to)

 

[John-K]

yeah I use one of those rcbs dispensers where you type in the charge and press dispense and it weighs it until at the amount wanted. I don't want my gun blowing up on me. I also measure every bullet, and if its over .1 grain I put it back in and redo it. If the bullet is .0025 over I pull it out and redo it (I don't have my micrometer seater yet) I measured my lands a few times. I do like to take pride in my work (if it works out like I want it to)

Is your scale on a level and stable surface? Have you verified it with checking weights?

I would also check the case length, along with smoking the neck of a case with a bullet only, NO PRIMER/NO POWDER and cycling it carefully through the action.


"measured it with the hornady thread on thingy" ???

Have you tried seating a projectile in the case ~0.100" with no crimp, cycling it carefully through the action so the lands push it back into the case, and then measuring the COAL?

Back off the lands another .010-.020 or load to book listed COAL (if book COAL is shorter).

Also, cross check your load data!

I shoot a cartridge with the same projectile, similar case capacity, but a SAAMI rating of nearly 10,000 PSI LESS! and the book lists my loads as 43-46.3gr of IMR4831 with a 140gr projectile. Apples and Pears, I know, but its something that should be double checked if you're having primer issues.

Speaking of, what primers are you using?

Look into "SEE" Secondary Explosion Effect

-John

 

[long range newbie]

rem 9 1/2 I trimmed it to 2.025, yes I did the no crimp thing thats how I checked to make sure it was correct, The hornady OAl gauge it threads on a brass and you push the bullet into the lands take it out and measure it.. Some brass are a tiny bit shorter but not much

 

[Twoboxer]

I used a home-made "Hornady screw-on thingee" to measure length. Maybe my case mouth was a little too tight, but there were marks on the bullet that indicated it had not just contacted the lands, but been forced a tiny bit into them.

Bottom line: To get the correct length-to-the-lands, I had to subtract the length of those marks. When you are dealing with hundreths of an inch, those tiny marks have meaning. Might be your problem, might not.

 

[John-K]

The hornady OAl gauge it threads on a brass and you push the bullet into the lands take it out and measure it..

If this is what you're talking about:

Hornady OAL Gauge - YouTube

I'd put it up on ebay.

As a Precision Machinist I was taught to remove as many variables, and use the actual parts in use for measurements when possible. Stacked tolerances are a killer.

K.I.S.S.

By using a deprimed case with a "tight" slip-fit projectile, once you have the OAL set, you can crimp the case, label it, and speed up die setup whenever you decide to switch between projectiles.

At $1.00/brass and $1.00/projectile, you can create a nice library that is more accurate and speeds up reloading, for the price of one of those tools.

I write down my favorite load data on the case, and keep it in the die set. So next time I'm loading say, 120gr SSTs, I write down the powder/charge on my pad, set the case in the shelholder, run the ram up, screw down the die until its snug, then run down the seater, and I'm pretty much set. You can switch between seating die settings in less time that it takes to pull the bolt and insert that OAL tool.

Though I enjoy reloading, I'd rather be outside, putting holes in paper ;-)

-John K

 

[armorpl8chikn]

I will go out on a limb and say it is directly related to using necked down brass. Could be a thick neck and or the brass is too long. possible donut situation as well. Get some ACTUAL .260 brass and start over. This is the problem I have with suggesting to new reloaders they can make brass from another cartridge. Yes you can, but there are things you need to know before you do so.

 

[Dan Newberry]

If the necks are too thick, that'll definitely cause a problem.

See if you can slip a bullet into the neck of a fired case. If it doesn't fall easily into the case (no neck tension at all), then the case neck is too thick, or else the chamber neck is intentionally tight...

 

[Short Round]

So you have a custom barrel? Call the smith that put it on and chambered it and see if he can provide you with the full reamer dimensions.

i write all that stuff down inside folders that I have for each gun. I verify the length to end of the chamber with a modified piece of brass and the little chamber stop plugs that sinclair sells.

 

[Fuzzball]

The cap's blown side hole is from a defective spot in the primer cup's metal, not over pressure. It's not common but it does happen to all primer brands. The matching burn pit in your bolt face is cosmetic only and does nothing to the safety of the rifle.

Your "flat" primers are due to setting the case shoulders too far back when FL sizing so it's not directly related to over pressure either.

 

[long range newbie]

I do have some 260 brass, but I don't have too much like 39 of it since I ruined one to do something.

 

[long range newbie]

I got a data book for my reloading and I'll look at the KISS thingy

 

[long range newbie]

Also would like to say keep passing on your skills man the skill of machining is dying especially the use of non computer controlled machine Because more and more people just learn how to use cnc and just push a button basically. I mean I'm just a kid but I'm learning how to do stuff. I have a logan lathe and small milling machine. Thanks

 

[turbo54]

What is the neck diameter of loaded cartridges? Measure several.

What is the neck diameter of spent cartridges? Measure several.

 

[1Sg (ret)]

The cap's blown side hole is from a defective spot in the primer cup's metal, not over pressure. It's not common but it does happen to all primer brands. The matching burn pit in your bolt face is cosmetic only and does nothing to the safety of the rifle.

Your "flat" primers are due to setting the case shoulders too far back when FL sizing so it's not directly related to over pressure either.

+1 on this weak primer material equals leaks.

 

[Fuzzball]

"+1 on this weak primer material equals leaks."

Well. the flaw gets blown away so it may be a thin spot but it seems more likely a bit of "trash" is embedded in the copper our primers are formed from. Primer makers have to buy cup metal from foundries in huge rolls and they have NO WAY of knowing if a weak spot is in there or not, And it only matters if the defect ends up at the unsupported radius of the cup.

If I get more than one from a batch I'll save the redt of the whole lot for lower pressure loads, like .30-30 or .35 Rem.

 

[81Z4ME]

If you have factory ammo, or factory cases seat a bullet or two (same type you loaded in the necked down cases). Measure the OD of the neck with the bullet seated. Then measure a couple of the necks on the rounds you reloaded with those same bullets. Compare. If the neck walls are thicker on the necked down cases it'll how in your measurements.

Weigh some of your cases (both types, the factory cases and the necked down cases) after you've resized and trimmed them. If the necked down cases weigh more then the case walls on that batch of brass may be thicker (reducing the internal volume) and causing increased pressure vs. the factory cases.

Make sure the cases are the same length. Longer necks can cause pressure issues.