Odd pressure issue

[dromia]

That indicates to me that your loads are marginal at best leaving no room for error at the bench or variation of components or climate.

[essexboy]

I've fired up the main pc and checked a few things on quick load, based on your o.a.l using a comparator I took a guess that your cartridge o.a.l will be close to 2.498 ins. I'm not sure what bullet you had the barrel chambered for but the free bore seems quite short, I had mine chambered off a dummy round and with an A-MAX I have an o.a.l with a comparator of 2.005 with the bullet 10 thou off jam.
Anyway with the load your using you are making drum roll 70269 psi ouch!!!!



Steve

[Mr_Logic]

OAL 2.510"

It's a factory Savage barrel, so it comes as-is. My 308 on the other hand is better, but that's not the issue...

I always raise an eyebrow at Quickload - it also said my old 243 load was OTT, but never had any problem with that and was 1gr within the Hodgdon max (51gr H414 with 55gr Nosler). Gave me around 4000fps. Didn't stick with it because it wasn't very accurate, but it certainly didn't have pressure problems.

If the pressure is that high, I would expect to see consistent pressure signs on all fired brass. The fact of the matter is that it's the odd one, and the others feel mild in every way - the bolt lift is always fine (even on the dodgy ones - the lift is fine but it's extract that's the issue), the primer is fine, there is no sign of excess pressure on the base of the cartridge either.

If it's consistent overpressure, why am I seeing the behaviour I'm seeing?

Also, can you please run QuickLoad against the 80.5gr Berger if it has it, and also the 80gr SMK? Could do with getting that program - I just wish I could buy it for download...

[ovenpaa]

3.6 has both and I can run it if you get stuck, just need to find a Winders machine...

[Mr_Logic]

Steve I think your original assertion that we're talking N540 pressure spike is right. I was out at Oundle this morning shooting the 223 but with the 80.5 Berger instead of the Amax.

When I tested this for pressure a couple of weeks back, I fired 5 rounds and found no pressure problems.

I fired the other 5 this afternoon, and again found no pressure problems. I then fired some with 25.7gr N540 in it, and had pressure problems. (stopped after two rounds - one was a fraction stiff, the other needed a whack to get the bolt back) Surprised to find such a difference for 0.2gr of powder, certainly not linear increase at that point.

I also took some old Varget loads out that I fired without issue but the other half found suspect. I did notice a fraction of resistance to extract but nothing needing any serious attention. The important part was that they were consistent. Once the 540 is done looks like I shall have to cough the extra and get more Varget in. And of course because it's Hodgdon and the supply is somewhat rare, I need to buy in as much as I can find. Ah, the joys of reloading in this accursed country...

[essexboy]

I put some more petrol in the pc and fired it up again and run some more tests, the following spat out using the O.A.L given for the A.max. These are all max loads before things start to go red

A.max 24.7g
Berger 25.2g
Sierra 25.1g

Claire has a 223 that was chambered for A.max ( longer throat) and the following loads are predicted

A.max 25.0g
Sierra 25.6g

Quickload predicts that for a .1g increase of n540 the chamber pressure rises by over 700psi

I ran a load of varget through it with the sierra bullet at 2.550 as per the manual and quickload came up with a max of 25.3, so it is pretty much on the ball

Steve

[Mr_Logic]

What did it say for MV? Curious now...

Many thanks for running it through though!

Certainly I did used to use the Varget load with 25.3, had to change primer for a bit and the CCI450s did put up pressure noticeably. Thankfully now have more Remingtons back in stock!

[essexboy]

If my memory serves me right 2995 fps

Steve

[Mr_Logic]

Thanks Steve!

That is my MV with the Bergers and N540, close with Varget too.