Primer Blow Out with NO Over Pressure Signs?

[jerrymrc]

Something is not right. The proposed data and the measured data say one thing and the back end of those rounds say another. I have loaded 168 SMK's @ 2.800 in LC brass and run them as fast as 2600 with a warm load of 2460 and 2700fps with varget in a gas gun.

[BuffCyclist]

Something is not right. The proposed data and the measured data say one thing and the back end of those rounds say another. I have loaded 168 SMK's @ 2.800 in LC brass and run them as fast as 2600 with a warm load of 2460 and 2700fps with varget in a gas gun.

Care to expand or throw out some possible causes you might think of? Because this is what I was thinking too, that I shouldn't be getting these hot of loads at 2600 FPS. If I was closer to 2700, sure, it'd make sense.

Also forgot to mention, I applied a very light crimp with the Lee Factory Crimp Die (as in, factory ammo in ram, ram up, screw in die until touching case and that was my crimp). It barely did anything to the cases, so I highly doubt I crimped too much. I could always load up some more cases without the crimp stage and see what happens.

[jerrymrc]

Care to expand or throw out some possible causes you might think of? Because this is what I was thinking too, that I shouldn't be getting these hot of loads at 2600 FPS. If I was closer to 2700, sure, it'd make sense.

Also forgot to mention, I applied a very light crimp with the Lee Factory Crimp Die (as in, factory ammo in ram, ram up, screw in die until touching case and that was my crimp). It barely did anything to the cases, so I highly doubt I crimped too much. I could always load up some more cases without the crimp stage and see what happens.

Many will say never but I do crimp for the gas guns (lee FCD) but never for a bolt gun. Also never crimped the smk's for anything. Nowhere for the brass to go and not needed.

[BuffCyclist]

Many will say never but I do crimp for the gas guns (lee FCD) but never for a bolt gun. Also never crimped the smk's for anything. Nowhere for the brass to go and not needed.

Well then maybe therein lies my problem entirely. Could that be causing the extreme pressure without giving me the velocity expected with high pressure?

I guess I'll just pull all remaining loads, resize, reload with same powder after weighing charges again and load the same brass again without crimp and see what happens.

I didn't even think of the crimp, I crimp all of my other reloads and just did it out of habit, but I crimp so lightly I didn't think that would be a potential culprit (in other words, it is such a light crimp, that when I do pull the bullets, there won't be a crimp ring on them, I guarantee it).

[XC700116]

Care to expand or throw out some possible causes you might think of? Because this is what I was thinking too, that I shouldn't be getting these hot of loads at 2600 FPS. If I was closer to 2700, sure, it'd make sense.

Also forgot to mention, I applied a very light crimp with the Lee Factory Crimp Die (as in, factory ammo in ram, ram up, screw in die until touching case and that was my crimp). It barely did anything to the cases, so I highly doubt I crimped too much. I could always load up some more cases without the crimp stage and see what happens.

That very well could be what's causing your pressures. Any crimp on a bullet that doesn't have a cannalure for that purpose should not be crimped at all in a rifle. it takes very little crimp to cause a pressure spike in that situation.

[Zombie Steve]

Some possible reasons:

-You're jamming the bullet into the lands. Book data goes out the window when you do this.

- Your scale is off. Test with check weights.

- You thought you grabbed 4064 off the shelf, but it was some other number salad like 4895.


XC is right... all of those pieces of brass are telling you No Mas. Also, when you're adding powder but the speeds aren't increasing it's time to stop.

[Zombie Steve]

One other thing I thought of... you sure they weren't magnum primers?

[Great-Kazoo]

One other thing I thought of... you sure they weren't magnum primers?

I mentioned that before. perhaps a mismarked box of LRM instead of LRP. Plus he was doing .4gr increments, possibly a few extra grains made it through without being noticed.

[DSB OUTDOORS]

The 1st pic on the right looks like its a loose primer to begin with. Could be a Swager was not set up correctly. Or primer pocket reamed out to much. LC brass has a thicker webbing to the case and should be able to get 4 - 6 reloads out of them. Looks like you've done your homework as far as data goes.

[BuffCyclist]

Some possible reasons:

-You're jamming the bullet into the lands. Book data goes out the window when you do this.

- Your scale is off. Test with check weights.

- You thought you grabbed 4064 off the shelf, but it was some other number salad like 4895.

XC is right... all of those pieces of brass are telling you No Mas. Also, when you're adding powder but the speeds aren't increasing it's time to stop.

Thanks for the other possible places to look.

First, I was loading to 2.800. I don't know where the lands are, I tried the dowel method (dowel down bore to face of bolt, mark with knife, put loosely sized neck/bullet in chamber, slowly slide bolt forward but don't lock, put dowel down bore again and mark with knife) but when I did that I was getting almost exactly 2.8" and I did it a good dozen times. So either I wasn't doing it right, or the distance truly is 2.8 in which case I should have more than enough room before touching the lands.

I was checking the scale with my 20g check weight every time I changed charges and it never varied.

True, I do have IMR-4895 (only other rifle powder) but it is unopened and I just double checked, so the only powder I could have used was IMR-4064.

One other thing I thought of... you sure they weren't magnum primers?

Yes and no. The box says they are for Standard rifle loads, but that doesn't mean Winchester didn't put magnum primers in a standard box.

I mentioned that before. perhaps a mismarked box of LRM instead of LRP. Plus he was doing .4gr increments, possibly a few extra grains made it through without being noticed.

I was weighing every charge, not using a powder dropper, so no extra grains made it through.

___

I decided I was going to go pull 10rds (38.0-39.6gr) tonight and reprocess/weigh/seat/etc them but then I thought I’d look for a crimp first. Turns out, I did NOT crimp them. I bought the crimp die, thought about using it but then after researching it found that it isn’t necessary for bolt actions (usually) so I decided not to. Some people claimed they saw better accuracy when crimping for their bolts and I thought I could play with it down the road.

Here are 10 loads from this batch (UNcrimped) and one dummy round (CRIMPED). It is obvious the loads I shot today were not crimped. There is a slight ring, but that is from chamfering the outside of the case mouth when I trimmed.