Seabeeken
Well-Known Member
Sounds like a great build. Cant wait to hear the speeds with the longer barrel. Heaviest ive used in mine was 225 AB. N550 shoots well in mine as does rl 17. keep us posted
338 RCM
- Thread starter gregsjt
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I did some preliminary pressure testing with my 22" Ruger using N550 and 250 Bergers this morning just to get an idea of possible speeds. I was surprised. I'm gonna post the charge weights and corresponding speeds. The COAL is set at 3.070". These are just pressure tested loads over a magneto speed chrony, no accuracy testing because my magazine in the Ruger is limited to 2.900" or less, so it's 230 ELD-X's and lighter only for hunting loads in it. But the new build will have a 3.100" so I figured I'd give it a try just for pressure data out of the Ruger.
55.0=2,445
57.0=2,567
58.0=2,611
59.0=2,659
60.0=2,700
61.0=2,746
62.0=2,780 (primers flattening but easy bolt lift)
63.0=2,830 (stiff bolt lift and firm ejector mark)
I got stiff bolt lift and a heavy ejector mark at 63.0 grains. Was very surprised at how much velocity could be attained from just seating those 250's out to the neck/shoulder junction increasing the overall length .230" longer than factory cartridge length certainly helped lower the pressures and fit the powder much easier. One difference I noticed was that pressure on those loads at that COAL weren't very noticeable until it happened all at once at 63.0 grains. The primers were flattening out at 62 somewhat but 63 is where everything went south. Seems like when you get to a certain compression is when it spikes/gives the pressure a huge jump. I know several guys are finding accuracy loads with the 338 SS around 2,800 fps and it holds around 5 grains more powder is all. That's what got me wanting to experiment this bullet weight with the RCM. With the longer 24" barrel coming on the new build and longer COAL of up to 3.100" I'm thinking 2,700 fps or somewhere there abouts with accuracy is a real possibility. But for now just some experimental data for everyone to see. I will update once the new rifle arrives in about 2 weeks and I've had a chance to do some more extensive testing with the 250's in it.
55.0=2,445
57.0=2,567
58.0=2,611
59.0=2,659
60.0=2,700
61.0=2,746
62.0=2,780 (primers flattening but easy bolt lift)
63.0=2,830 (stiff bolt lift and firm ejector mark)
I got stiff bolt lift and a heavy ejector mark at 63.0 grains. Was very surprised at how much velocity could be attained from just seating those 250's out to the neck/shoulder junction increasing the overall length .230" longer than factory cartridge length certainly helped lower the pressures and fit the powder much easier. One difference I noticed was that pressure on those loads at that COAL weren't very noticeable until it happened all at once at 63.0 grains. The primers were flattening out at 62 somewhat but 63 is where everything went south. Seems like when you get to a certain compression is when it spikes/gives the pressure a huge jump. I know several guys are finding accuracy loads with the 338 SS around 2,800 fps and it holds around 5 grains more powder is all. That's what got me wanting to experiment this bullet weight with the RCM. With the longer 24" barrel coming on the new build and longer COAL of up to 3.100" I'm thinking 2,700 fps or somewhere there abouts with accuracy is a real possibility. But for now just some experimental data for everyone to see. I will update once the new rifle arrives in about 2 weeks and I've had a chance to do some more extensive testing with the 250's in it.
Seabeeken
Well-Known Member
63 grains is definitely too high and the pressure spike was certainly noticeable. What does your program say for 60.0 grains with those same parameters?
Seabeeken
Well-Known Member
Seabeeken
Well-Known Member
Yeap that still is way too high. My goal was to drive the 250 Bergers to 2,700 fps mark with accuracy out of a 24" barrel. It doesn't look like that will be very feasible. Hornady list 56.7 grains of N550 for the maximum load with their 250 grain bullets. I would think that Hornady's bullets will have a longer bearing surface than the Berger's do. They're claiming a maximum velocity of 2,500 fps from a 20" barrel. So if we consider the Berger having less bearing surface then I would guess you could go up a grain higher than Hornady's book (that gives you another 50 fps if you went up to around 58 grains for a max) and then when you add in the 4" longer barrel compared to their test rifle that will probably give you another 80 fps (these are just educated guesses) so now we're sitting at 2,630 fps with a 250 Berger. On my quickloads program it also shows that RL-17 is supposed to be around 45 fps faster than N550 with the 250 Bergers at said parameters. So if and I do mean IF all that worked out to be true then you'd be sitting at 2,675 fps with the 250 Bergers. Still not my minimum of 2,700 fps that I was hoping for.. I might have to just stick with the 225's/230's at around 2,800 fps for the best long range load it's sounding like as of right now. That being said, I am thinking that I might have to take off from work a few hours tomorrow and test some of these loads for accuracy in my 22" Ruger single feeding them since the magazine isn't long enough in that particular gun for magazine feeding the 250's just to keep experimenting and have some idea. I will continue updating my results if I have a chance to do some more testing tomorrow. Thanks SeaBeeken for your pressure calculator info!
Seabeeken
Well-Known Member
My pleasure, was just concerned about safety there. What about a lighter bullet? Dont know what you are hunting but I've been running 175 hammers at over 2900 fps. I actually hit 3100 with ball powder but I was getting pressure signs at about 3050. I never did compare bullet drop of the 175 at higher speeds to the 250 bergers. Might be worth a look.
Ok so some updates for everybody: the 250 Bergers didn't pan out like I was hoping. When pressure testing this time around I started noticing pressures (primers starting to flatten) around 58 grains of N550 and around 59 grains of RL-17 giving velocities of only around 2,625 fps with N550 and 2,642 fps with RL-17. That's just not fast enough for what I had in mind so I discontinued testing the 250's at that point. I went back to my original load for this rifle which is the 230 ELD-X's and refined it just a touch this afternoon. Now I'm running 61.8 grains of RL-17 with a cartridge overall length of 2.840" giving me an average velocity of 2,775 fps from my Ruger's 22" barrel. I'll post some pictures below. It is a very consistent .3 MOA load (around 3/8" at 100 yards). Single digit ES usually too. Pictures of my rifle on my range, picture of my Quickloads data with a predicted PSI of 67,966, and picture of the 2 shots I put into the bullseye of my 725 yard steel target while confirming sight in are below.
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I did work up a load this afternoon also as far as lighter bullets go; 200 grain Hornady SST's. It didn't take me long to find a pretty accurate load for them either. When my new 24" RCM comes in here in a couple weeks that's gonna be my first priority is to work up a lighter bullet weight load for it for a large Canadian whitetail stomper rifle; lite weight rifle that hits hard at reasonable deep hunting ranges. Thinking I'll try the 180 and 200 grain Accubonds, 185 grain Barnes TTSX, and I also have some 200 grain Hornady SST's. Here's a picture of a 3-shot group I shot today with the 200 SST's out of the Ruger (gonna stay with the 230's in the Ruger though because it's just such a great load and I may carry it with me for family thanksgiving elk hunt in Colorado come November). Anyways, here's the picture of the load I developed today for 200 SST's with the specs written on the paper. It's also putting out around 66-67k psi according to quickloads.
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adk hunter
Well-Known Member
Great info. Thanks for sharing!
I had some very helpful PM's with Seabeaken and tried the 175 Hammers. I was looking for a little more weight so went to the 205 Power Hammer. Love everything about this bullet. Going to get the load through the chronograph and run it out to reasonable distance.
I have more room in the CA magazine and a 24'' proof...
I had some very helpful PM's with Seabeaken and tried the 175 Hammers. I was looking for a little more weight so went to the 205 Power Hammer. Love everything about this bullet. Going to get the load through the chronograph and run it out to reasonable distance.
I have more room in the CA magazine and a 24'' proof...
Seabeeken
Well-Known Member
Ive taken a number of whitetails with the 185 Barnes before switching to the hammers. I tried the 186 shock hammer first and asked Hammer for a lighter bullet for deer and then they made the 175 HH. Never looked back. Awesome bullet, Win 748 shot the 186 SH .333 @ 2802 fps.
With the 175 HH I tested TAC, 2520, Lvr, IMR-3031. Out of those, IMR-3031 shot the best with a group of 0", yes a perfect hole and an ES of 10.
IMR-3031 pressured out at 57.5 gr and 3049 fps but best load was 56.5 gr. BTW, I had a 243 that shot 100 gr Hornady interlocks into the same hole also, it loved 35.5 gr of 3031. The 175 HH always gives me full penetration so never an issue there and it always drops the deer.
I am preparing to test N-540 and N-530 as soon as I'm done planting.
Some nice groups there papa, keep it up, its a very accurate cartridge as is its offspring, the 6.5 PRC.
GTG to Charlotte area, have a great day
With the 175 HH I tested TAC, 2520, Lvr, IMR-3031. Out of those, IMR-3031 shot the best with a group of 0", yes a perfect hole and an ES of 10.
IMR-3031 pressured out at 57.5 gr and 3049 fps but best load was 56.5 gr. BTW, I had a 243 that shot 100 gr Hornady interlocks into the same hole also, it loved 35.5 gr of 3031. The 175 HH always gives me full penetration so never an issue there and it always drops the deer.
I am preparing to test N-540 and N-530 as soon as I'm done planting.
Some nice groups there papa, keep it up, its a very accurate cartridge as is its offspring, the 6.5 PRC.
GTG to Charlotte area, have a great day
I'm curious about your 205 grain power hammer load. I ordered some 205's and some 213 hammer hunters to test in the new 24" rifle when it's shipped to me next week. With this new one I am gonna be trying to go with lighter weight bullets because the main usage for it will be large bodied whitetail deer. The 205's down to the 175's will be the weight range I'll be focused on.
Do you feel as though the 175 Hammers have better terminal performance over the 185 Barnes you used to whitetail hunt with?
