more home load questions.........

[fieldwanderer]

The story so far;

 

I bought everything while waiting for my rifle to be made. other than the equipment, this included;

 

Hogdon superformance

sierra gameking 65gr (.224)

ppu brass (.22/250)

cci 200 primers.

 

I prep'd the brass very carefully, trimmed to 1.902", I used a lyman primer pocket uniformer deburred the flash holes f.l. resized the lot and primed obviously.

 

Next step was to load quite a few up to book length (2.350") with varying powder charges (which were weighed very carefully) everything was done to +/- .001"

 

Eventually I got the rifle and was able to go try it out. I won't list all the chrono results etc but here's the thing;

 

Load data's rare for this powder and bullet but I eventually found that sierra's advice is to use the data for their 63gr bullet which is; start 38gr max 42.7gr so far so good but, at 38gr the velocity is as as expected but I got pressure signs so, I fired the next few increments, mostly no pressure signs but there was some occasionally - dodgy ground I know but I was curious.

 

 

Some googling revealed that this is a common thing with ppu brass. So, I put it all to one side and bought some remington brass in the hope I'd get a more positive indication of what's o.k. and what isn't. Yesterday, I fired 30 of these new loads, all equally carefully prepared except I didn't touch the primer pockets this time. The pressure signs (slight shiny spot from cutouts in bolt face) were much more predictable this time and didn't show at all until the max load. Velocities were down a good 150fps though but I'm not worried about that. The problem was some that failed to fire, it's as though the primer pockets are too deep. I tried some more today and out of 27, six fired - 21 didn't obviously, I'm now also using a length slightly less than the chamber (-.020").

 

Any ideas where I go next? I'm not getting anywhere really like this; I either get over pressure because the ppu brass has less volume or failure to fire for an unknown reason with the remington brass :unsure: the groups are looking promising but I need to know A. it's safe and B.it's gonna go bang when (and how) I want it to!

Edited November 3, 2013 by fieldwanderer

[fieldwanderer]

Thanks fister, I'll have a look into the firing pin - as far as I know, everything's in tip top condition and, unlike other sako models, the 75's firing pin isn't adjustable but it certainly sounds feasible.

 

I'll also get some lapua, when the old bank balance has recovered a bit

[fieldwanderer]

I had a quick look having read your post, obviously I can't see the firing pin when fired but with the bolt removed from the rifle it sticks out a long way really - a good couple of mm, it looks almost enough to punch through the primer if it could. Which, I guess means it's down to;

 

Headspace?

weak or broken spring (it's certainly not broken)

some problem with the remington cases' dimensions

 

The ppu brass, the dent in the primer is well pronounced, notably less so with all of the remington (including those that fired). All primers are out of the same box.

 

I've found a temporary "fix" via my googling though. Someone else with the same problem with the ppu brass was told to load them on the long side - the theory being the ppu brass has less internal volume, hence the pressure, and seating the bullet further out increases that volume slightly. I made some up at .010" off the lands and It worked! no pressure signs at all and they fire reliably BUT, it hasn't really helped with the whole load development process

Edited November 3, 2013 by fieldwanderer

[Dougy]

Hello Mr Wanderer,

 

you have a 75 nice , i hope you eventually get it sorted out, i can highly recomend getting some Lapua cases, i got some from a very helpfull member off here after he recomended them to me once at Catton, i fully intend on getting some more now. Even if i have to go and pick them up

 

What twist is it i take it you have gone for a 12 or 10, i have not long had one done in a 1-12 and it likes the 53grn vmax but i'm guessing you are intending to go long range with it

 

 

Just clocked you Sako, looks nothing like mine does it but tell you what it looks bloody good.

I understand how you felt with regards to being fed BS i was treated the same by another outstanding smith,

 

We (a mate of mine had his done too)dropped them off for re-barrels and were told its not a problem as we have barrels in stock, a hand then waved down showing us the barrels, yes lads one of these will bo going on yours. Brill we thought.

Months passed and i gave them a ring, "hello, yes there at the proof house it will be a couple of weeks" fine i did ask if i could pick them up as i was nearer to Brum, but no they had to go back to make sure every thing was spot on, OK no prob.

Rang back after 2 weeks and we were told they hadnt even got the barrels in yet they were waiting for them from Border.

I rang border who hadnt even had the order from B&BS

 

 

Strange that, story all seemed to be mixed up..

 

Picked them up after being sitting in a strong room for nearly 5 months collecting dust, he wasnt a happy chappy at all specially after he was told he was a BS itter and if he could cope with the work he should have said in the first place.

 

It wasnt Steve Kershaw or Dave Wild, they have both given me exellent service Dave was the chap who ended up with the job in this case

Edited November 4, 2013 by Dougy

[fieldwanderer]

Yeah, I think that's probably the way forward - I'm near certain the rifle's tickety-boo. I have a load for the ppu brass that's down to just over 1/2" at 100yds but I reckon it can be improved. It'll do for foxing for now though - I'm pushing them 65gr gamekings (1:10twist) at just over 3700fps - 1900ft/lbs which is more than enough!

 

I'll get better brass when I can afford to though.

 

So far, I'm very happy with the rifle. I was a little surprised at the recoil given it's sheer weight but, given the 1/2moa groups, I don't think it'll be a problem at all. I do think it deserves an expensive scope though, I think that'll have to wait until spring.

[fieldwanderer]

............speaking of springs I put a "packer" behind the firing pin spring this morning and went out with all the ammunition that had failed to fire - it certainly did this time which tells me the spring's suspect, however, the trigger felt heavier to me. Do you think a new spring would solve the problem?