Raised Primers

[Prospero]

Hi all,

I am new to reloading and have been working with a mate who has some experience to develop a varmint load in .270 Winchester. Using new brass (RP), Winchester large rifle primers, Hornady 110gr V-Max Varmint and ADI 2208 smokeless powder. Using a Lee powder thrower and adjusting each throw on a set of Lee safety scales to ensure accuracy. All brass was chamfered inside and out and primed with a Lee auto prime.

Started with 5 rounds loaded at each of the following weights - 43.5gr, 44.5gr, 45.5gr, 46.5 and 47.5 for a total of 25 rounds loaded.

The brass was being filled 80-85% of capacity.

Starting with the lightest loads at 43.5gr fired the 1st round and checked the brass. A little blacker around the neck perhaps than factory rounds. Primer OK, no sign of flattening. Chrono 800m/s

Next the 44.5gr. Same blackness around the neck, no marks or rings on the case, but the primer has become raised slightly. Chrono 850m/s. The check the remaining 4 rounds and double check that the primers are all seated correctly. They are. Fire the remaining 4 rounds and each one does the same thing as the 1st. Primer "pops" out slightly (less than .5mm?? haven't put the verniers on them). No sign of flatness of the primers. Chrono read 850m/s.

Not sure what would be making this happen - headspace? pressure?

Not knowing what was going on, wasn't game to try any of the heavier loads.


Any wise heads out there with some suggestions?

Cheers.

 

[Mal H]

My best guess is that it was, indeed, pressure - low pressure.

In almost all cases, the primer will back out of the case when a round is fired. However, it is pushed back in the primer pocket when the case releases from the chamber walls and is forced backward by the residual pressure. This action is true for almost all calibers, handgun and rifle.

Your loads are on the light side and the bullet is light for a .277, so the bullet is probably well along in the barrel or even out of it by the time the case releases. There's not enough residual pressure to reseat the primer in the pocket.

I'll wager the "problem" (it really isn't one) will go away as you increase the powder load.

That's not to say there isn't a headspace problem, but the pressure angle is far more likely considering the loads you are using.

 

[ReloaderFred]

I agree with Mal H. Those are indications of a load that is too light for the caliber.

By the way, welcome to the forum. It's good to have another member from "down under".

Hope this helps.

Fred

 

[steve4102]

My best guess is that it was, indeed, pressure - low pressure.

Bingo!

 

[rcmodel]

The backed out primers, sooty necks, etc. sound like not enough powder to expand the case and seal it in the chamber.

Repeatedly firing those loads will gradually set the shoulder back each time they are fired.
If you don't have excess headspace on your brass already, you soon will have.

There really shouldn't be enough headspace available for the primers to be able to back out that far.

I might back off the sizing die until you get stiff bolt closing on an empty case, then bump up the power level and see what happens.

rcmodel

 

[Roccobro]

There really shouldn't be enough headspace available for the primers to be able to back out that far.

I might back off the sizing die until you get stiff bolt closing on an empty case, then bump up the power level and see what happens.

Thats exactly what I was thinking...

Justin

 

[Sunray]

Hi, Prospero.
"...850m/s..." That's 2,788fps. ADI's site shows 3072fps as the velocity for the starting load for a 110 grain bullet using 2208. Your powder thrower isn't throwing enough powder. It may be the size and shape of the powder grains, the thrower or a lack of experience. In any case, your loads aren't what you think they are.
When working up a load you need to weigh each load.
Do this.
Beginning with the starting load, given in your manual(43.0), load 5 rounds only(or whatever the capacit yof your rifle's mag is). Go up by half a grain of powder, weighing each load on your scale, loading 5 of each, keeping them separate, until you get to the max load in your manual(48.7).
Then go shooting. Shoot at 100 yards, for group only, slowly and deliberately off a bench.
Change targets between strings of 5 and allow time for the barrel to cool.
When you find the best group, sight in.

 

[markypoos]

Hiya,

I'm the mate that was helping Prospero with his handloads, and new member to the forums.

Every throw from the Lee Powder Thrower were measured on a set of Lee powder scales that has been zero checked, and also checked with a known weight just to be sure everything is hunky dory.

We did exactly as outlined in your "Do this" with the exception that we started at 43.5 and went up in one grain increments, instead of halves. Slow deliberate groups off sandbags, at 100 yards, letting the barrel cool between groups.

Best group so far has been a little over 30mm, at 47.5 grains. We were planning on trying 47.0, 48.0, 49.0, and 50.0 grains next, but after reading your suggestion we'll probably look at the half grain intervals as well to paint as full a picture as possible of group sizes.

Kindest regards,
Mark

 

[markypoos]

Oh and the verniers show the primers proud by around one fifth of a millimetre.

Not a lot but enough to concern us that something wasn't right.

Kindest regards,
Mark

 

[Prospero]

Thanks all for the help and good advice.

Headed back to the range with the remaining loads and the primers did indeed "come right" as the load size increased.

Still got some work to do on the loads, but it's starting to look good. 1st 3 rounds at 47.5 gr cut the same hole, the next two shots were slightly off, but that may have been either me or a hot barrel.

Cheers.