OzFclass

Hopefully someone here can shed some light on a problem I seem to be having with my loads .
New to this form of shooting ( was a trap shooter , and been a hunter for most of my life , using factory loads ) .

Got a new rifle built , Barnard P , True Flite heavy palma barrel in a Mastin stock , cross between F class & FTR in 308 .

Been shooting 155.5 Bergers & 2208 powder . Seem to be working well & fairly accurate ( the rifle is , not me ) .
Finally got hold of a chrony & did some testing on the weekend . At 46.0 of 2208 I am getting 2990 fps , with only 5 fps difference over 3 shots , fairly happy with that , but when I try the 185 Juggs I get massive pressure problems , I am completely blowing the primers out of their seats , and splitting the primers into 2 pieces .

Someone I know shoots the Juggs using 45.5 of 2208 with no real signs of pressure , I tried 44.2 and suffered pressure problems , (Blew primers out & leakage through the primer seats ) , using the chrony last weekend I loaded 3 using 44.0 & it blew the primer out again , and splitting the cap & cage into 2 pieces , but the speed was 2803 fps for that load , I did not continue any further .

My question is why does it seem to shoot the 155.5's about normal to most other barrels , but when it comes to the 185's they seem to suffer from pressure problems ? And 2803 fps seems to be fairly quick for such a light load of powder ?

Both are seated to give 0.010" jump .

If anyone can shed some light on this it would be greatly appreciated .

Julian

Julian, you need a longer throat on your chamber when using the 185s. If you are seating both bullets to the same jump then what you are doing is jamming a whole heap more bullet into the case and compressing the powder, then up go your pressures.

Be very careful when using loads recommended by someone else, could safe in their rifle and not yours. Start low and work up.

Just my two bobs worth.

Cheers
Danny

I would make a considered guess that the 45.5 load mentioned is for Palma brass.
If you are using LR Lapua brass 45.5 would be an overload.
Depending on barrels our 185 Jugg loads run between 2810 and 2850 fps.
These are good working loads giving long case life in Palma cases.

If it is LR cases I would venture you are at least a full grain over max?
I would check your scales for accuracy and powder lot?
How old is the powder?
How many times have cases been fired?
We had a case of excessive pressures some years ago on mild loads?
Turned out cases were overlong and jamming mouth into chamber throat!
Pressures soared!
Just a few initial thoughts?

We run 155 and 185 in same barrels with same throat which works ok for us.
But as put forward a short throat at same jump would cause high pressure also.

Julian,

One of the basics of trying a new load is to start low and work up - you're risking serious damage to your boltface blowing primers. I think you should go down a couple of grains e.g. 42 grains and start there, working up until you get the first undesirable pressure signs, then back off a little. The reason you're getting excess pressure using the same charge (and even 1 or 2 grains less) as your mate can be one or more of many reasons e.g. faster powder batch, tighter barrel, barrel fouled, different primer, different chamber, different brass etc. etc. You might also find that your mate can run the 155.5s safely with a higher powder charge than you. Also, the velocity you mention with the 185s will probably be lower because of the blown primer. I'm not familiar with what the 185s run at normally, but don't forget chronos often vary by 50 fps when compared.

Hope this saves you from cutting holes in your bolt-face !

Alan

PS: Didn't think of throat length as mentioned by the others. Sounds likely to be a major reason.

Thank you all very much for the advice .
The throat was done by Phil M & must be made to suit both the155's & the 185's .
The 155's are just in the cases & the 185's fit nicely , don't think they are squashing the powder much .... just a visual observation , nothing technical . All cases are trimmed to length , these cases have been fired 3 times & the primers felt nice & firm when I seated them .

I have no idea about powder age , could be old , but not sure .

I will go out & test again on the weekend , will drop down to say 42 & work up from there , I was hoping to get 2750 out of the 185's , looks like I will be lucky to get 2500 without signs of pressure .

The scales are Redding beam scales that do seem quite accurate .

Thank you all for the help , I appreciate it .

Julian

Are you using Lapua Brass ? Other brands may be too soft ....
I could not see the reference but this would be essential to working up hotter loads than normal
Measure the bases of your cases, if the primers blew out you may need to throw them away, even if they have only had one firing ! The primer pockets may be too loose now ....
Whenever this happens i would stop right away to avoid ruining brass...
When i tried 185gr loads i worked up from 43gr 2208 with no pressure problems 43-44gr, but i did not follow through with this beyond 44.
What is your COAL ? compare with another shooter using juggs.....

Let us know what happens !

I think you might be right Shane , I can vaguely remember a conversation where he may have said he was using the small primer Lapua's .

OK , well that makes sense now .

Honestly thought that going 1.5 grains lower than a known load was enough to be safe . Live & learn I suppose .

Have thrown away all of the blown primer , leaked primer & any that did not seat the primer tight brasses away , 35 out of 100 ......
Fairly expensive lesson , but one that won't be repeated . And they are Lapua cases .

I searched the net everywhere trying to find known loads that work for people , but I guess most don't like to give away their hard earned secrets , and being fairly new , I don't know too many people to ask .

So thank you all for taking the time to reply , I think I have got it sorted now . Will go out again on the weekend & try again . Once I have got my speeds & pressures sorted , I will then try & find the best grouping .

Julian,
Shane G is right & expert in all things FTR.
What I did as a starting point, I had the 11T barrel chamber throated for 185 Jugs, Lapua LR brass, GM210 primers, 2208 powder, loads started at 43gns with Magneto speed crony so accuracy is fairly close and shouldn't be considered perfect but as a guide.
I finished at 45.7gn with about 2830fps & no pressure signs. This was fine in my rifle so it may not be in yours and each barrel is different. There isn't a go to load.
The advice i had was Jugs need to be jammed, mine liked to be jumped for better grouping so you need to work out what is right for your equipment.
If your barrel isn't a faster twist to suit the jugs you may struggle.
Geoff

My advice would be to use Palma cases.
I know they are quite a bit more expensive initially however they handle pressure better than the LR cases.
My guess is that with all that extra brass at the base the Palma cases are less loath to expand at a given pressure.
The extra expense is compensated by a much longer useful life with reasonable loads.
Most people seem to be able to achieve 2800 fps with 185 Juggs in 30 - 32 " barrels using them with 2208.
Some barrels can do 50 fps more with similar case life.
I would say nobody wants to actually advise a load because of all the implications these days if something goes pear shaped.
There are so many variables which impact on pressures that it is impossible to do so.
We have covered some of these above but not all for sure!
It is why everyone advises beginning at much lower thresholds as a starting load.
That is the main reason rather than being unwilling to share load data.
Shane

I totally understand what you are saying , and it makes a lot of sense .
Thank you all for your input . I have learnt more in the last 24 hours than I have in the last 2 months .....

I will get some Palma cases just for the 185's , and continue to run normal ones for the 155.5's .

Thanks again & hopefully see you all out there one day at a shoot .

Julian