Help identifying pressure problem

[jonaddis84]

Went out today to confirm my zero after removing scope. Shot a 5 shot group, then moved windage and shot another 3 rounds to confirm. All are identical loads, 44.6 Varget out of a chargemaster, 175 SMK in Lapua brass with 210M primers. Loaded around .010" off the lands.

It was around 30 degrees out, I think I developed this load around 50 degrees. Shooting with suppressor on for all shots. Gun is Savage 308 stock barreled action 22" bbl, bolt wont close on a no go gauge.

This is what I ended up with.

The first pic is the first 5 shots.

Next is the 3 shots after, had a sticky bolt, and obviously brass flow into the ejector.

And finally the bolt head, if this helps at all.

 

[223ai]

Re: Help identifying pressure problem

How long did you let those rounds sit in the chamber before pulling the trigger? How much are you bumping shoulders back with each sizing?

 

[jonaddis84]

Re: Help identifying pressure problem

Not long in the chamber, loaded individually, maybe 5 seconds before firing.

These were all neck sized, however I compared the length to the shoulder with the comparator and it is the same as a freshly sized round. All but one of the three chambered easily, and that one is clearly visibly as the older piece of brass in the 3 shot group. The other two pieces only have 2 firings on them.

Im going to start FL sizing every time now. But I dont understand how I can go from no pressure at all, to all the sudden having pressure bad enough to flow into the ejector, but not flatten primers. I could understand the case on the far right of the 3, that is an old piece that definitely needed sized, but the other two are basically brand new cases.

Could I have an issue with my bolt?

Also, I checked over all length of the brass thinking maybe they had gotten too long, but not even close, its still .03" from coming close to the leade.

 

[MitchAlsup]

Re: Help identifying pressure problem

Can't really tell for sure due to the photog quality, but it appears to be hints of ejector swipe on the first set of 5.

 

[jonaddis84]

Re: Help identifying pressure problem

You think Im just too hot on my powder charge? Ive been using this load for over a year now with no apparent problems, this is why Im so confused.

I sure hope I dont have to pull down the 100+ rounds I have loaded up and redo them.

 

[BobinNC]

Re: Help identifying pressure problem

Powder lot change???

 

[jonaddis84]

Re: Help identifying pressure problem

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BobinNC</div><div class="ubbcode-body">Powder lot change??? </div></div>

Yes that is possible, I was using 1 pounders, not sure if these rounds are loaded from them or the 8lb I have now.

I guess Im pulling rounds and starting from scratch

Unless you think there could be an issue with the gun? It probably has around 1500-2000 rounds through it, could a worn out barrel cause these kinds of problems?

I know I know, I need to keep track of data better!

 

[Swan]

Re: Help identifying pressure problem

Powder lot change would be my guess as well. I just went through the same issue with a new keg running hotter than the previous one. Looks like I'll have to drop charge a .1gr or so.

 

[ChadTRG42]

Re: Help identifying pressure problem

2 things that pop out to me.
1- the lot of powder. When you change lots, you need to re-test your load and verify nothing has changed, Varget especially. Just switching lots can vary your speed and pressures. If your charge is 44.6 grains, then I'd load up 44.4, 44.6 and 44.8 and see what you get. The load should remain very close to the original load. I gained 77 fps just by switching powder lots of H4350 in my 260 Rem with the same charge. And the loads were running hotter.

2- I assume you shot these with the can on. I've seen loads not show any pressure signs during load development when shooting slow. Then, when you start firing more rounds and the barrel and supressor get hot, there is more back pressure which causes excessive pressure on the case. Take the can off when you get this pressure, and see if the pressure signs go away. If it goes away, then that load is too hot when shooting multiple rounds with a can on. If it still shows pressure with the can off, then you just have a hot load, and need to back it down some.

 

[sniperaviator]

Re: Help identifying pressure problem

Wrong powder?

 

[jonaddis84]

Re: Help identifying pressure problem

Im thinking most likely the rounds that showed the pressure were loaded with the new 8lb jug of powder. Going to pull them all down, and start over with a new load. While Im at it I may even cut my barrel down to 20 since Ive been wanting to do that anyway.

Thanks for the help guys, I need to start keeping track of this stuff better.

Do you think those cases are junk now or can I keep using them?

 

[Bozcoyote]

Re: Help identifying pressure problem

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sniperaviator</div><div class="ubbcode-body">Wrong powder? </div></div>
+1

 

[jonaddis84]

Re: Help identifying pressure problem

Not wrong powder, Varget is the only extruded powder I use right now.

 

[MitchAlsup]

Re: Help identifying pressure problem

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jonaddis84</div><div class="ubbcode-body">Unless you think there could be an issue with the gun? It probably has around 1500-2000 rounds through it, could a worn out barrel cause these kinds of problems? </div></div>

No, but a seriously fouled barrel CAN.

Might give the barrel a through clean and get the copper out just to be sure.