The 25 sst...up and running

[elkaholic]

Did some testing with the 90gr Absolute Hammers yesterday.

25SST
26"
1&7
CBTO 3.261 -.001"
COAL 2.750
NT .001
Fed 210
ADG Brass
87*
90gr Absolute Hammer


RL26

60 3586
61 3660
62 3687 ej mark
63 3750 -
64 3805 -
65 3849 - ~100% load density
66 3903 -
67 3980 - out of room for powder


H4350

54 3528
55 3566
56 3612
57 3654
58 3698
59 3759
60 3796 ej mark
61 3855 -
62 3915 -
63 3977 - bolt lift ~95% load density

Shot 3 shot groups at 100yds with H4350 in .5gr increments from 59-61.5gr. Almost all groups were around half moa except for 61gr at 1". Testing was done with a suppressor attached.

Best group was .4" at 59gr with a velocity of 3760. Brass lasted 8 firings here.

61.5gr shot .6" at 3880 fps. Brass lasted 3 firings.

H4350 looks like a good powder for this case. For the conditions 9cl 12mph wind and slight mirage I thought they shot pretty good and should do much better in more ideal conditions. Not to mention the round count on my barrel is pretty high. Definitely a step up in velocity from the 92gr HH's I tested last year.

I started pressure testing H4895 also but haven't finished yet. It looks like it will be to fast for this combo with a lower load density to. Should finish out 100-200 fps behind h4350

Also had a 3/4" hard-end steel plate at 100yds that I put a 90gr hammer into at 3900fps just for the heck of it. It almost made it all the way through!

Now I just need to test them out on game.

I bet some N555 would crack 4000'!!

 

[CA48]

I think my local store has N555 Il give it a try if they do.

Went out this morning to verify my 59gr load of H4350 at -.001" and try a few other seating depths. Wind was still blowing 15mph but I think I found my hunting load. Still want to verify things when it calms down.

Yesterday with this load at 87* I had a faint ej mark but was still getting 7 or 8 firings. It dropped to 72* while shooting this morning and the faint ej mark is gone. So this load should do well in the cooler temps Il be hunting in. I also tried some Norma brass and it made me appreciate that there's ADG available these days.

The 3 groups measured below are 59gr of H4350 at -.001"

 

[CA48]

What do you think the barrel life would be with something like this? 3760-3900 FPS that's just crazy speed. Would be a great point and shoot deer gun and yotes

There's no way to know without testing it. H4350 is a double based powder with a higher burn temp than H1000. What I can tell you is after measuring throat erosion that one day of pressure testing with N570,RL26, and Retumbo, around 45 rounds total will burn up more of your throat than 200 rounds fired with H-1000 while keeping the barrel cool and only firing 2-3 rounds at a time.

I think it's safe to guess that bbl life could easily be dropped to the 400-600 round range if your firing hot loads at 3900fps and getting the barrel hot.

Currently my barrel has 1,108 rounds through it.

 

[DocDoc]

H4350 and H1000 are both single base powders. They do not contain nitroglycerine, which gives more energy and a higher burn temperature. H4350 does burn hotter than H1000, which is one of the coolest burning powders.

 

[CA48]

You're correct Doc my mistake, H4350 is a single base powder.

 

[Ross1147]

All, my smith just emailed letting me know my 25SST is in its final stages and ready to be test fired. He requires 3 rounds to test fire prior to shipping the gun out. I have a couple of questions. One, I have 25 SST brass from Rich already, I don't need to make a false shoulder or load long to jam the bullets for fire forming correct? If I do I'll have to go the jammed bullet route because I don't have the gun. With Rich's reamer what's a good CBTO measurement with the 131s for a slight jam? Second, if I wanted to send a few loaded with 115 VLDs what's a safe place middle if the road load with N565? I do have 131 BJs, but I'd rather waste the 115 VLDs. Thanks!

 

[highdrum]

All, my smith just emailed letting me know my 25SST is in its final stages and ready to be test fired. He requires 3 rounds to test fire prior to shipping the gun out. I have a couple of questions. One, I have 25 SST brass from Rich already, I don't need to make a false shoulder or load long to jam the bullets for fire forming correct? If I do I'll have to go the jammed bullet route because I don't have the gun. With Rich's reamer what's a good CBTO measurement with the 131s for a slight jam? Second, if I wanted to send a few loaded with 115 VLDs what's a safe place middle if the road load with N565? I do have 131 BJs, but I'd rather waste the 115 VLDs. Thanks!

The sst line is load and shoot, but It's all 6.5mm and needs necked down prior. The 25sst chamber has fairly short freebore, it's 0.088 but that does keep a 131 blackjack out the powder space. It'd be better with 120-140 imo. The 131 like to be 5k, 18k and 32k off lands if I recall.

 

[couesaddict]

Well it was a tough hunt and I was too picky so tag soup for me but my sister in law filled hers on the last day for a little coues deer meat buck. 390yds with the 131BJ. In tight behind the shoulder and out the off side shoulder through the heart. Silver dollar exit and dropped him like a sack of hammers. Here's the exit with the tips opened to .030". Pretty happy with the performance.

 

[elkaholic]

Congrats! That does look like good performance

 

[couesaddict]

All, my smith just emailed letting me know my 25SST is in its final stages and ready to be test fired. He requires 3 rounds to test fire prior to shipping the gun out. I have a couple of questions. One, I have 25 SST brass from Rich already, I don't need to make a false shoulder or load long to jam the bullets for fire forming correct? If I do I'll have to go the jammed bullet route because I don't have the gun. With Rich's reamer what's a good CBTO measurement with the 131s for a slight jam? Second, if I wanted to send a few loaded with 115 VLDs what's a safe place middle if the road load with N565? I do have 131 BJs, but I'd rather waste the 115 VLDs. Thanks!

All I did to the brass when I got mine was neck it down. I didn't touch the shoulder and it all chambered pretty tight for the first firing. No need to jam with this one. I started .010" off and it shot so good I never messed with it. Personally, if it were me and I was doing it without the rifle in hand, I'd probably seat the blackjacks around 2.850" oal. That or seat long and send him the dies maybe??

 

[elkaholic]

All I did to the brass when I got mine was neck it down. I didn't touch the shoulder and it all chambered pretty tight for the first firing. No need to jam with this one. I started .010" off and it shot so good I never messed with it. Personally, if it were me and I was doing it without the rifle in hand, I'd probably seat the blackjacks around 2.850" oal. That or seat long and send him the dies maybe??

The new brass now is completely formed too so not even any taper to remove other than normal .003-004" tolerance

 

[Ross1147]

Thanks, I just ran the brass through the die ensuring I didn't touch the shoulder. Loaded 60.0 grns of N565 and seated the Berger 115 to the boattail shoulder junction. From what I've read in this thread you can get to around 61-61.5 with the 131 so 60 behind a 115 should be safe. Thanks again!

 

[couesaddict]

Should be fine I'd think. 61 grains of n-565 with the 131 is starting to show some pressure in mine so when you move onto that bullet I'd back off some just in case.

 

[elkaholic]

It is better to go easier the first load. Primer pockets last longer.
I might load 58 if it were me.