Just wondering if anyone here has played with the 260 imp 30. I have a new build coming up and need to decide on a chambering. I have been running a straight 260 with 142's @ 2800-2825, oal 2.830, 26" bartlein. I really want to try to get up to 2900+. I will be switching to AW mags so oal will be able to be increased some. Any thoughts on the imp 30 chambering?
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260 Imp 30 velocity gains?
- Thread starter psmith
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I went through the same consideration before having a build finished. Here is why I ended up with a plain (unimproved) 260:
1. Brass is easier to get, and/or make.
2. Barrel life is longer.
3. Brass life is longer...not much, but a little.
4. Now that Laupua makes 260 brass, there is some VERY strong plain brass available.
5. The additional range that the additional velocity gives me is only 100-250 yards over the standard 260. As the standard 260
with good loading technique can reach around 1700 yards before it goes transonic, I considered how often I truly shoot over 1700
yards in order to justify all the extra work, and shorter brass and barrel life. The answer I came up with was never. I have
other gear to reach out further if I need to, and in the 3 years since I had my 260 built, I have yet to shoot 1700 yards, let alone
any further.
However, if you live somewhere that allows you to shoot over 1700 yards on a regular basis, then that would make a big difference in my thoughts on this matter. For me, those sorts of distances are 2-4 hours driving each way, so I rarely shoot that far.
1. Brass is easier to get, and/or make.
2. Barrel life is longer.
3. Brass life is longer...not much, but a little.
4. Now that Laupua makes 260 brass, there is some VERY strong plain brass available.
5. The additional range that the additional velocity gives me is only 100-250 yards over the standard 260. As the standard 260
with good loading technique can reach around 1700 yards before it goes transonic, I considered how often I truly shoot over 1700
yards in order to justify all the extra work, and shorter brass and barrel life. The answer I came up with was never. I have
other gear to reach out further if I need to, and in the 3 years since I had my 260 built, I have yet to shoot 1700 yards, let alone
any further.
However, if you live somewhere that allows you to shoot over 1700 yards on a regular basis, then that would make a big difference in my thoughts on this matter. For me, those sorts of distances are 2-4 hours driving each way, so I rarely shoot that far.
Brass would be worked a little harder because of the fire forming, and additional powder used to get the extra velocity. Granted, the additional work probably wouldn't amount to too much, but it is a minor consideration. Generally speaking, more powder for more velocity means more pressure, and almost always means faster wear on the barrel's throat.
Drawings show the 260 imp 30 to have a sharper shoulder, longer neck, and increased case capacity. That is how they get more velocity out of the case. It is a nice case, but there is a downside to everything. Extra velocity comes at a cost.
Drawings show the 260 imp 30 to have a sharper shoulder, longer neck, and increased case capacity. That is how they get more velocity out of the case. It is a nice case, but there is a downside to everything. Extra velocity comes at a cost.
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I'm running a 260Imp30 in a 28" Heavy Palma PacNor.
No pressure signs pushing 140s to over 3000fps (Re17 and H4350) but I run them at 2930fps to keep inside the accuracy node.
Fireforming is not an issue. Load a 260 case and shoot it. Accuracy is excellent both forming and formed.
I'm using Lapua .243 brass that I sized to .260 for 8 firings then formed to 260Imp30 for an additional 4 firings (so far). Primer pockets are still firm. Zero case length trimming required.
Using the short throated reamer, the OAL with 140VLDs jammed 20T was 2.88". (bullet seated deep in case)
Reaming the throat out to put the boat tail junction above the neck/shoulder junction took the OAL to over 3".
Short throat Vs long throat? No difference in accuracy in my rifle.
Hammerhead, I am having a 260Imp30 built right now. I am planning on using Re17 and the Berger 140VLD's using Lapua .260 brass. I am limited to AIAW mag length at .295-ish, but was curious (if you don't mind sharing) what your Re17 load is and if you have any recommendations as I/we move forward with these builds. Any preference on Re17 vs. H4350 (or H4351sc), and what kind of groups have you been getting? I appreciate your help and input, I'm sure psmith and I are in the same boat, all signs point to a great cartridge, but there is such little info to be found.
Thanks again,
Thanks again,
Svendogg, the following loads are what I used with the short throat.
Re17: With 140VLDs jammed 20T, OAL=2.88", 43.6gr produced 2939fps when fireforming cases and 2950fps with formed cases.
H4350: With 140VLDs jammed 20T, OAL=2.88", 44.6gr produced 2939fps with formed cases.
Load testing at 300m in quiet conditions, Re17 produced 5 shot groups under 0.4moa but H4350 regularly shot groups in the 2s. I opted for H4350.
Note: I started with low single loads (42gr H4350 & 41gr Re17) and worked up in steps of 0.5gr to find the pressure limits. However, I reached my velocity target before I reached the pressure limit and still have no idea how hard the 260Imp30 can be pushed. The resulting charge/POI plot revealed a likely node around 2920fps-2950fps and I worked on that.
Re17: With 140VLDs jammed 20T, OAL=2.88", 43.6gr produced 2939fps when fireforming cases and 2950fps with formed cases.
H4350: With 140VLDs jammed 20T, OAL=2.88", 44.6gr produced 2939fps with formed cases.
Load testing at 300m in quiet conditions, Re17 produced 5 shot groups under 0.4moa but H4350 regularly shot groups in the 2s. I opted for H4350.
Note: I started with low single loads (42gr H4350 & 41gr Re17) and worked up in steps of 0.5gr to find the pressure limits. However, I reached my velocity target before I reached the pressure limit and still have no idea how hard the 260Imp30 can be pushed. The resulting charge/POI plot revealed a likely node around 2920fps-2950fps and I worked on that.
From what I'm reading about this cartridge here, I'm considering having my standard 260 re-chambered.. The ability to simply shoot any 260 ammo you want is HUGE if you get stuck somewhere without enough of your 260IMP30 ammo.. And case life doesn't appear to be much of an issue. It would seem that all the "conventional" wisdom about wildcats doesn't seem to apply to this round.
Especially interesting is that it works well in gas guns too. I would usually expect some feeding issues with the sharper shoulder, but even there, it seems this round doesn't comply with "conventional" wisdom about wildcats. Maybe the "wisdom" ain't so wise after all....
Especially interesting is that it works well in gas guns too. I would usually expect some feeding issues with the sharper shoulder, but even there, it seems this round doesn't comply with "conventional" wisdom about wildcats. Maybe the "wisdom" ain't so wise after all....
Hmmm the more i keep comin back to this thread the deeper i thinking.. re-chamber my 60? Yea but im already getiing .2s with 2870 fps..hmmm
My brass life improved with the ackley chamberings. Just anneal the brass after the fire form if it bothers you. My experience with them is for varmint calibers, but I learned enough to know I dont think it will make a difference on target with a mag feed bolt gun. I've used the 6.5x47 and the .260 extensively, and there is no practical difference on target in my opinion. Those two represent a greater spread of capacity than the standard .260 to an improved .260.
I think the wisdom still applies. HH is getting 2940 with a 28" tube. I was at 2825 with a standard 260 and 26" barrel. Brass growth should be less with the sharp shoulder but I would hazard a guess that most of us lose the brass before its worn out. What interests me the most is reports of 3000 fps with no pressure signs. Assuming 25 fps/inch, can I hit an accuracy node at 2950 with a 26" barrel. Sounds like it might be possible.
Ummm...doesn't the 6.5 Creedmoor have a 30 deg shoulder as well? Not sure what I see as a benefit of a ".260 imp 30"...
260-30° has more case capacity than 6.5creed.
I say DFB (don't fucking bother) chasing the incremental increase in capacity UNLESS you can mag-feed the cartridge with bullet seated at or above the NSJ. If not, it's hardly an increase in capacity at all.
Considering that 6.5-284 achieves ~3000fps from ~53gr of powder (not considering specialty powders like RE17 or N550/N560) does it seem reasonable to think 2950-3000 would be achievable with ~45gr...assuming similar pressure??
Sharp shoulders stretch less each firing. An advantage when you fire brass many times AND trim with a hand crank. However, most all chambering reamers allow for brass ~.020" longer than the SAAMI spec, so for a tacmach rifle, it's totally conceivable you'll lose a piece of brass (even 243/260/308) before it needs a trim. Similarly, I actually PREFER a bit of stretch, because it gives something for the Giraud to actually do. The 30-40° cases stretch so little they often leave no material for the Giraud to clean up.
I think ultimately, in regard to ballistic performance, the 260-30° is to the 260 as the 260 is to the 6.5creed
Which is to say the difference is hard to detect, because other factors like barrel, powder lot, bullet lot and environment are a bigger deal than the slight changein cartridge capacity.
That all said, the 260-30° sure looks sexier than standard 260.
I say DFB (don't fucking bother) chasing the incremental increase in capacity UNLESS you can mag-feed the cartridge with bullet seated at or above the NSJ. If not, it's hardly an increase in capacity at all.
Considering that 6.5-284 achieves ~3000fps from ~53gr of powder (not considering specialty powders like RE17 or N550/N560) does it seem reasonable to think 2950-3000 would be achievable with ~45gr...assuming similar pressure??
Sharp shoulders stretch less each firing. An advantage when you fire brass many times AND trim with a hand crank. However, most all chambering reamers allow for brass ~.020" longer than the SAAMI spec, so for a tacmach rifle, it's totally conceivable you'll lose a piece of brass (even 243/260/308) before it needs a trim. Similarly, I actually PREFER a bit of stretch, because it gives something for the Giraud to actually do. The 30-40° cases stretch so little they often leave no material for the Giraud to clean up.
I think ultimately, in regard to ballistic performance, the 260-30° is to the 260 as the 260 is to the 6.5creed
Which is to say the difference is hard to detect, because other factors like barrel, powder lot, bullet lot and environment are a bigger deal than the slight changein cartridge capacity.
That all said, the 260-30° sure looks sexier than standard 260.
go for it P! it looks cool, everybody will think its the way to go as wells you shot, and i want to do one also
and you'll be my guinea pig. p.s: turbo will just be jealous cuz you will have a "custom" round to
. see you guys soon.
and you'll be my guinea pig. p.s: turbo will just be jealous cuz you will have a "custom" round to
. see you guys soon.go for it P! it looks cool, everybody will think its the way to go as wells you shot, and i want to do one also
and you'll be my guinea pig. p.s: turbo will just be jealous cuz you will have a "custom" round to
Bob, SAC chambered my new match rifle in 6 Super.
6.5mm's are SOOO 2011.
By the way, Mark has 6mm and 6.5mm SLR reamers. Plus if you like, you can borrow my personal 6/6.5 SLR reamer.
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ya i know he told me about it and how well you did. if 6.5's are sooo 2011 what the hell is a 300wm?
thanks for the reamer offer but i don't think i can be very precise with a cordless drill. and the slr is my other thought.
thanks for the reamer offer but i don't think i can be very precise with a cordless drill. and the slr is my other thought.
ya i know he told me about it and how well you did. if 6.5's are sooo 2011 what the hell is a 300wm?
thanks for the reamer offer but i don't think i can be very precise with a cordless drill. and the slr is my other thought.
300wm is still legitimate today in 2013, and will be into the future for:
1. Chuck Norris
2. Dudes with tiny weiners trying to compensate
...don't remember you rocking a beard, Bob...
Which are you?
Running a 6.5 SLR/S Improved, so far accuracy is great. I've broken in the barrel and will ship off for melonite treatment before I finish doing my load development.
I am keeping track of it here: 6.5 SLR/S Improved - Ready for testing
If you want another flavor go for it, otherwise any of the established 264 cals will do.
I am keeping track of it here: 6.5 SLR/S Improved - Ready for testing
If you want another flavor go for it, otherwise any of the established 264 cals will do.
300wm is still legitimate today in 2013, and will be into the future for:
1. Chuck Norris
2. Dudes with tiny weiners trying to compensate
...don't remember you rocking a beard, Bob...
Which are you?
i'm working on the beard lol. but until then i'm going to shot the 300 and drive my vette to matches.
Im running a 260ackley 28" fluted Krieger #6. 101thou freebore.
pushing 140gr nosler custom comps jammed 10 thou into lands
my mild load achieves about 2960fps, the hot load gets just under 3100fps, but eats brass. 2-3 reloads out of lapua before primer pockets give up.
i used to use ar2209, but now use RL 25 as it gives similar velocities at slightly lower pressure.
pushing 140gr nosler custom comps jammed 10 thou into lands
my mild load achieves about 2960fps, the hot load gets just under 3100fps, but eats brass. 2-3 reloads out of lapua before primer pockets give up.
i used to use ar2209, but now use RL 25 as it gives similar velocities at slightly lower pressure.
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