of reduced loads and primer signs

11 February 2002, 15:35

I've been loading some loads in my 308 with the following:

180 HORNADY RN
26 grains IMR 4198
Rem cases
CCI 200 primers
No fillers

These loads are for plinking, since I like to shoot a 'real' gun rather than a 22.

My question/problem is that some of the primers back out of the pocket slightly. I don't beleive this is from high pressure. Does anyone have any idea why they do that? Is it a problem?

11 February 2002, 16:54

<2ndaryexplosioneffect>

It is from high pressure. Research the term secondary explosion effect. More is less, less is dangerous.

Shoot safe,
Mike

11 February 2002, 22:35

carcano91

quote:
Originally posted by dogtagger:
My question/problem is that some of the primers back out of the pocket slightly. I don't believe this is from high pressure.

Correct asumption.
Generally speaking, primers sticking out to the rear of a cartridge bottom are signs of low pressure, and often also sign of a bit too much headspace.

Carcano

12 February 2002, 03:30

Dutch

Carcano is correct. However, the "detonation effect" is real, and may be possible even with powder as fast as 4198. I would stick with SR4759 loads; it's just not worth the risk. See your Speer manual. HTH, Dutch.

13 February 2002, 01:26

dogtagger

Dutch,

The load is an 'estimate' that I deducted from the speer #11 manual. They don't list reduced loads for 308 in 180 grain bullets, but do so with 300 savage, 30-40 and 30-06. I took the middle of the road approach between 30-06 and 300. All list 4198 as the powder with 180s.

Seems like the opinion is mixed on why the primers backed out. The speer manual says it's a sign of low pressure...

Any other suggestions for plinking loads?

13 February 2002, 03:12

Dutch

Dogtagger, I got to looking at the Speer, and you are right. That's what they recommend. Should be about as safe as anything.

I can't see anything wrong with a primer backing out. It introduces a little variability into the load, but for a plinker, that doesn't matter, does it? FWIW, Dutch.

13 February 2002, 03:32

<2ndaryexplosioneffect>

If your primers are not backing out in your standard load we can assume you do not have a headspace problem or primer pockets stretched from previous hot loads. If you can feel your primers seat tight, or mike the case head to confirm it has not stretched, it almost has to be high pressure. I canï¿½t imagine why you want to shoot 180 grainers for plinking in the first place. Load up some 110 gr. plinkers or go with a slower powder and get the case filled up.

Shoot safer,
Mike

13 February 2002, 05:08

dogtagger

Mike,
I'm using the 180s simply because I have a bunch, and was trying to find a practice load that will shoot well in my rifle, with a point of impact about the same as my hunting load (also honady 180s). In this respect the load fails, impacting several inches low at 50 yards. I will be trying lighter bullets to see if I can find a round that has ok accuracy and impacts the same poa as hunting loads. Though I don't claim any expertise on the subject, I think the loads are safe, and relatively low pressure. IMR lists 4198 with 180s at about 33 grain loads with pressure about the same as other powders (52,000 CUP). My loads fill the case a little more than half way.

Hot loads in my gun have shown up with (slightly) flattened primers, but primers have never backed out before. By the way, only about 1 in 4 or 5 back out.

The primers backing out don't cause any other problems I can detect, such as failure to eject etc...

Low velocity/noise loads are cheap & great for shooting quickly & at moving targets. Great practice.

13 February 2002, 06:20

carcano91

quote:
Originally posted by 2ndaryexplosioneffect:
If you can feel your primers seat tight, or mike the case head to confirm it has not stretched, it almost has to be high pressure.

Mike, I am afraid you might still be mistaking what the original poster asked. He did NOT ask what flattened, expanded, squished primers might mean (sometimes :-) ). He asked specifically about a primer sticking out to the rear, beyond the cartridge bottom. This CANNOT be a sign of high pressure, for obvious reasons.

Regards,
Carcano

13 February 2002, 07:51

JerryO

quote:
Originally posted by dogtagger:
The primers backing out don't cause any other problems I can detect, such as failure to eject etc...
Low velocity/noise loads are cheap & great for shooting quickly & at moving targets. Great practice.
DP

Primers backing out is common with light loads. Some people explain it as the primer driveing the case forward then the grip on the chamber holds the case from coming back over the primer.

The solution has been listed as drilling out the flash hole. I think I used .099 inch at first but went to .110 to get a standard drill size of 7/64 inch. I use the next smaller size for small rifle primers.

It solved my problem. I followed the caution to mark the cases and use them for light loads only.

The most common very light load I have seen listed for the .308 is 12 grains of the fastest pistol powder (like red dot, I use 14 gr of 700x in a 30-06 with 130 gr bullets). I get about (just over) 1/2 of a full case with the 1/4 weight of powder. I found it interesting that 1/4 the powder was giveing me about 1/4 the bullet energy of a normal load. That is 1/2 the normal velocity (1800 ft/sec for the 130 grain bullet)

If I load much lighter, I get a lot of gas around the case as the neck doesn't expand enough to seal. Of course if you have a tighter neck to throat, you will have less problems with this.

Cast bullet shooters should have lot's of opinions and solutions for you. I got the suggestion for drilling out the flash hole in an article on cast bullet shooting. I was a little concerned as it also recommended useing magnum primers with the very easy to ignite powder. The idea seemed to be to burn all the powder prior to the bullet leaveing the case. The powder can then expand and the pressure drop as the bullet goes down the barrel.

Just a caution to consider. I have read (and believe) that the pressure raises very fast as you go up in powder weight. So be very careful if you choose to increase the loads over what you find in a manual (I guess even as you approach the max level in the manual).

I got my loads from the lyman manual as listed for cast bullets.

JerryO

13 February 2002, 07:57

BCB

Take a case and just put a primer in the primer pocket and shoot it. NO POWDER--NO BULLET...THE PRIMER WILL "BACK-OUT". I would bet that ain't from high pressure!!!

Lee's reloading manual lists a method of reducing powder charges for reduced loads. I have use the math provided and I have had good results reducing powder charges. Good-luck...BCB

13 February 2002, 13:12

waitaminit

To ensure a more consistent ignition, you may want to use a filler.
It's a good advice to go for a faster powder as the risk of the secondary explosion effect is reduced, and the cartridge expands better, thus reducing heavily sooted cases, a messy gun and gases heading backwards into your face.
A correct headspace (you feel it when closing the bolt)leaves not much room for a primer to back out.

13 February 2002, 17:51

Magnum Mike

The primer IS backing out from LOW pressure! I have experienced the same. The pressure is low enough that it does not push the case back tight against the bolt face to reinsert the primer. You can also have the same effect in revolvers.

The light loads make a real nice plinker or small game gun out of a hunting rifle.

mike

------------------
NRA Life Member

United States of America, Love it or LEAVE IT!

14 February 2002, 07:37

dogtagger

I'm thinking on trying lighter bullets to see if I can find a plinking load that will shoot to the same poi as my 180 grain hunting load.

Any suggestions for a powder/bullet combo for the 308?

15 February 2002, 03:34

rickt300

I used 23.5 grains of powder(4198) in a 30-30 behind a 170 grain cast bullet and it performed perfectly. I say you have a low pressure problem. Are your cases smokey around the neck and shoulder area? I say increase the load a grain at a time until the problem disapears. When you get there you will have a very accurate load.

15 February 2002, 13:50

dogtagger

rickt300

Don't seem to be getting any soot down on the case below the neck. Sounds like the primer issue is no major problem. My speer manual list some other powders for lighter bullets (SR 4759) when shooting reduced loads, some even suggested pistol powders (unique?). Has anyone tried those with success? I haven't had any experience with them myself...

15 February 2002, 15:17

rickt300

I have used 24.5 grains of IMR 4227 under a 110 grain Speer plinker with great results in a 30-06. I have also used 27.0 grains of the same powder under a 220 grain cast bullet in a 303 British. I believe the first load would work well in a 308. In the Speer manual #9 with a 110 grain bullet starting load for their 110 grain HP varminter in a 308 is 25 grains with max listed at 29 grains. Starting velocity is 2120 and 2469 fps at 29 grains. For a starting load with 4198 it lists 32.0grains with the 110 grain bullet for 2500 fps.