.308 win start loads ... Extruded primers ?

[Bakersfield7.62]

So today I fired some new test loads of 168 smk I want to make a round with decent accuracy so I can use them in both of my .308 rifles , m700 sps-v and a norinco m305 the loads tested were full legth sised with a rcbs Match die set, rem brass cci br2 primer and the 168smk were set at 2.800 , IMR 4885 @41.0 grains group was @ 1 MOA for the m700 and 4moa with the m305 not so great I usually have better results with both , the real problem is that the primers were pushed out on some about 10 thou happend with both rifles is the load showing pressure high or low to push the primer out? the brass is from my test only pile that has been loaded 4 times or so not to be used anymore the primer pockets have been uniformed to insure they are below flush for safety reasons also pockets felt fine while primeing

Today I also fired same loads but with 41.5 grains of IMR 4064 primers were out but only a bit so you could feel them a touch above flush none of the primers were flattened like I usually see with the m700 pet load of 45gr of RL17 I'm thinking the loads were under powered but the data is much different from serria - hogdon serria claims 41.5 max with 4895 hogdon says filler up 45.+ compressed not to sure what to do ?

 

[Longwalker]

You have a headspace problem. Most likely you are resizing the brass too much, but your rifles might have too much headspace even with normal brass. The primers protrude on low pressure loads, and the brass will stretch to re-sat the primers on high pressure loads. You can manage this problem with the excellent measurement tools sold by Hornady that were invented by Stoney point and are called the Head and shoulders gauge - they fit on a standard caliper and allow you to measure how much, or if, you are pushing the shoulder back on bottlenecked cases.

 

[barsik]

sounds like maybe the case is staying fully forward in the chamber and the primer is backing out under pressure until it contacts the bolt face. is this first load of 41 grains of IMR 4885 a starting load? if it is and your primers are backing out 10 thou, then it pretty well tells you what your headspace is. the second load of 41.5 grains of IMR 4064 is still low pressure but more pressure than the IMR 4885. I was unaware that there was an IMR 4885 powder,is it new or did you mean IMR 4895 ? in any case you should have soot on the case/case neck because the pressure isn't high enough to stretch the case to the chamber. if you don't have soot on the case then something else is going on.my sierra load data book(1978) shows the 308 starting load of 39.0 grains IMR 4895 for the 168 gr Matchking, and 40.8 grains of IMR 4064 as a starting load. I NEVER use max load data, the info is for that particular rifle chamber only. another issue is temperature, and some powders are very sensitive to low temps, as in erratic velocity and pressure signs. please post information about soot on case before you continue reloading.

 

[Bakersfield7.62]

So my cartreges are shorter than the chamber and with not enough pressure to send the case back agansed the bolt to re seat the primer ?
Is this bad as far as safety goes or just reduced brass life and not as good for accuracy ?
I expect the norinco to have a sloppy headspace but not my m700 should I fiddle with the siser die to try to make the cartridge fit the m700 chamber better ? I could back the die off a bit to try to Match the head space of the m700 ex... Say the headspace of my chamber was 1.635 in the m700 and I was bumping the shoulder of my brass to far say 1.620 the cartreges have to grow 15 thou to fill the chamber and if the pressure is not great enough to do so the primer would come out the 15 thou

What I should do is take fire formed brass from the m700 measure the head space than back my siser die off Untill it only bumps the headspace back a thou or so from fire formed ,Is this the cure ?

 

[Bakersfield7.62]

http://i1359.photobucket.com/albums/q784/blazingbaker/ECD335DF-370A-4CA2-883C-A0CEF1D7FCAA-258-00000028E7B3F00D_zps9b6d5758.jpg[/IMG

Powder charge was of 41 grains IMR 4895 and only the one case had a primer stuck out 10 thou the others are just out by feel above flush none were flattened ,I only fired 10, 5 in bolt gun and 5 with the m305 in the above pic you can see the small air gap between case head and calliper

 

[Bakersfield7.62]

 

[Bakersfield7.62]

The serria load data PDF from 6mmbr.com says max load at 2500 fps is 41.3 gr of IMR4895 but all of my other load data ex Lyman 49th and hogdon data in 2013 reloader magazine says max around 45 grains and over 2700 fps !

 

[maynard]

You are bumping the sholder back too far with the sizing die. There is nothing wrong with the headspace on your 700. Each rifle may like different ammo, one load will not the the answer to both.

 

[07blackwater]

You are bumping the sholder back too far with the sizing die. There is nothing wrong with the headspace on your 700. Each rifle may like different ammo, one load will not the the answer to both.

Exactly what I was going to say.

In addition, if you neck size only for the next firing I bet it will go away because the case isn't going to lengthen. Right now the case is gripping the chamber and the first thing to move is the primer. After fire forming it won't do that anymore.

Read about partial full length sizing if you don't have a neck die. It will save your brass too.

Another thing, forget about using primers flattening as a guide. Some are soft and will always flatten. Some will flatten in non fire formed brass because they are moving during firing as well.

 

[tiriaq]

I think I would keep the 700 and M-14 loads separate. The M-14 likely has more generous headspace than the 700, and if you are sizing the cases to fit either, sooner or later you are going to get case separations.

 

[07blackwater]

I think I would keep the 700 and M-14 loads separate. The M-14 likely has more generous headspace than the 700, and if you are sizing the cases to fit either, sooner or later you are going to get case separations.

Yes.

I missed that he was using 2 different rifles since it's my first day off and I'm on the sauce.

Good mod.

 

[Bakersfield7.62]

I think I would keep the 700 and M-14 loads separate. The M-14 likely has more generous headspace than the 700, and if you are sizing the cases to fit either, sooner or later you are going to get case separations.

I have a load for the bolt gun only 185gr I just thought I would tailer a load more for the m305 whle keeping it MOA or better from the bolt gun , and throw away the brass after 4 reloading's to prevent a case rupture I don't know of any thing I could do that would make the ammo m305 only I'm not gonna risk neck sise only with that rifle because if the rounds don't slip in the chamber and get stuck halfway in the bolt could set them off out of battery

 

[Bakersfield7.62]

Thanks dudes I think I may have solved the problem here is what I did ...
I took some fired brass that was previous shot from the m305 which has a longer head space than the m700 the brass would not chamber in the bolt gun then I readjusted my siseing die Untill it bumped the shoulder back just so the bolt of the m700 would close with out resistance
I think I am going to buy the hornady shoulder to base measuring attachments for my calipers that way I could see how much longer the headspace is on the m305 I'm thinking it is probably 1.640 or so that seams to be the norm