New Creedmoor load test

[Unclenick]

I popped the out-of-published-load-range warning into your post. Required now.

Keep us up and what happens and what your results look like.

[kilotanker22]

Thanks Unclenick

[kilotanker22]

CAUTION: The following post includes loading data not covered by currently published sources of tested data for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assumes any liability for any damage or injury resulting from the use of this information.


Well 44 grains of StaBall 6.5 got me up to 2710 fps. ES and SD were better though. Group size was sub MOA, but kind of danced around in a circular pattern. I can load this hotter, but H-4350 is still 50 fps faster and I use.more than 2 grains less powder to do so.

Retested the 140 Matchking in the new brass with H-4350 load. Velocity was a little low, but still shoots groups you could cover with a dime.

[kilotanker22]

I did notice that I had to reduce my powder charge significantly with this Peterson Brass. A full 1.2 grains less powder, but only lost like 45 fps.

[kilotanker22]

Again today, no better than .9 MOA ten shot groups shot three such groups. .9, 1 and 1 MOA ten shot groups. That was with the 147 Grain ELD Match bullet and a Hodgdon's max charge of H-4350.

I am nearly certain that this bullet will need to move closer to the lands to improve the groups. Problem is that they are at mag length and still .075" off the lands.

I think that I am going to start load workup over again. I AM GONNA DROP to 39 grains of H-4350 and start these bullets at the lands. Work up in half grain increments to find my max charge at the lands.

I am also gonna order some MDT magazines without the binder plate. That will allow me to load out to 2.960". These bullets at the lands are 2.920". Once I find my maximum charge I will do a seating depth test. Although I am not sure it's worth a complete load workup. I only have around 500-700 shots left on this barrel.

[Rimfire5]

kilotanker22,

I don't know how many rounds you have down that tube but you might be underestimating the life left in that barrel.

I have two 6.5mm Savages in 6.5mm CM - 12 LRP and 12 FV - with over 4,250 and 2,850 rounds down range respectively and they shoot as good or better than they did with 200 rounds down range.

Unless you have more than that down your barrel, you may have many more rounds of life left.
I keep shooting until I can measure a difference in average group size over a significant sample.
I only had one barrel in another rifle, a .308, start to lose accuracy due to wear, and that was because it started out with a chamber that was 0.080 deeper than SAAMI recommended O.A.L. and by the time the rifling eroded an additional 0.090 I couldn't seat the bullets out any longer and still maintain neck tension.

[kilotanker22]

I have about 1300 rounds down the tube after today. I am pretty sure my main issue is that this bullet needs to be closer to the lands.

[hounddawg]

Just out of curiosity Kilo have you ever tried any 4831SC with the heavier bullets? I had one 26 inch barrel (.260 Rem) that loved that stuff with the 140's and 142's

[kilotanker22]

I have not, H-4350 shoots so well with excellent velocity spreads. Everything else shoots really well except for this bullet. I mean 1 MOA ten shot groups are ok, but I know the rifle is capable of a third that size.

I will load these long and single feed them for now to see if they will shoot like every other bullet I have tried. Once I have those MDT magazines I will be able to load them at the lands.

I think I might start at 40 grains of H-4350 instead of 39. Starting the bullet close to the lands will raise pressure, but also moving that bullet .065" further out of the case will increase case capacity a little.

I will need to load 20 rounds at each increment. 10 for velocity testing and ten for group size. If I get lucky and one of the increments shoots the way I want it to then I am done. If not then I will choose the one with the best velocity spread and do a seating depth test. Also right now I am at the lower end of my barrel time node. Hopefully lowering the charge weight and moving the bullet closer to the lands will decrease barrel time and get me more towards the middle of that node.

[hounddawg]

Well I only had one barrel out of four that prefered it over H4350 and that particular barrel loved Varget with 120 and 123's.

[Unclenick]

Kilotanker22,

I don't know how close to the lands you intend to go, but if you start in full contact with the lands, lowering the charge about 10% will keep the pressure close to the same as when you have your bigger jump.


Regarding shot-out barrels, I think most people expect them to just gradually shoot larger and larger groups. That can happen with uniform throat errosion, but when a barrel really starts to die, it is usually because the throat is becoming non-uniform due to chips breaking off the alligator skin thermal stress cracking pattern that eventually forms. When that occurs, the uneven throat can tilt some bullets more than others, so you start to get fliers.

When I shot out my first M1A barrel, I had shot a dozen rounds clean onto a slow-fire target and suddenly got an uncalled 9 at about 10:30. I figured it was me, but within another twenty rounds, I had another in the same place. Over the course of the summer it went from one-in-twenty to one-in-ten and then one-in-five, at which point it finally dawned on me that the problem wasn't me and I needed a new barrel.

In an article on barrel life in Precision Shooting magazine in the late '90s, Sierra's range was used to shoot out .308 Win barrels made of chrome-moly and stainless, some cryo-treated, some not, some using moly bullets and some not, but the criteria for life was the same: the appearance of the first flier.

G. David Tubb says his throat conditioning abrasive bullets can recover throat uniformity and double the life of a barrel, thereby (though the throat will be longer). I haven't tried this form of firelapping yet.

[hounddawg]

G. David Tubb says his throat conditioning abrasive bullets can recover throat uniformity and double the life of a barrel, thereby (though the throat will be longer). I haven't tried this form of firelapping yet.

I like them for barrel break in but have never tried them on recovery. I have a .260 barrel that has over 2K down it and starting to throw flyers that I will try them on either next month or September. I will remeasure the lands, and do an adjust on base to ogive, clean, shoot 15 rounds then 15 of the Tubbs, clean, and then 15 more. See if flyers are reduced

That is if I remember, I am in the middle of relocating and have to setup a reloading room and find some range time first.

[kilotanker22]

So far I have observed around .010" of erosion. That is only based on CBTO to the lands in this rifle using the same Hornady bullet I first started with.

[Unclenick]

That may slow a little now the corners are rounded. Note, too, you will often get different readings from tangent and secant ogive bullets because the former tend to touch the lands at bore diameter first, while the latter tend to touch them at groove diameter first. This is thought to be part of the reason secant ogives can be fussier about cartridge runout.

[kilotanker22]

Unclenick, that is precisely why I have used the same bullet to track throat erosion. I do see what you speak of though. A Sierra 140 grain Matchkings CBTO at the lands is using the Hornady tool is 2.288". Where the Hornady 140 grain ELD Match bullet measures 2.272". The 147 grain ELD Match bullet's CBTO is 2.272" as well.

[kilotanker22]

Assuming that the tool will measure CBTO where the bullet meets the diameter of the tool. I just assume that the Sierra has a longer surface at full diameter than the longer more slender Hornady bullet.

The Sierra shoots so damn well, I just want a higher BC for longer shots. I have recently acquired the use of a farm where I can stretch out to 1200 yards.

[kilotanker22]

I decided to reduce the starting load by 9% I will begin testing at 38 grains of H-4350 increasing by .5 grain increments. So I will test 38, 38.5 and 39 grains of H-4350 this afternoon. With the bullet at the lands. I am hoping to find velocity similar to what I have now while reducing barrel time by moving the bullet closer.

[kilotanker22]

So far velocity wise
38 grains Avg= 2541
38.5 grains Avg= 2560
39 grains Avg= 2591

All had single digits SD numbers. The 39 grain load had an extreme spread of only 8 FPS.

Letting the barrel cool for awhile before I shoot groups.

Seeing the velocity I am getting here. I plan to load 39.5 grains and 40 grains for the next range trip. Since my top velocity at 39 grains is 150 FPS slower than my previous load

[kilotanker22]

Coincidentally all of these loads showed vertical stringing at 100 yards. All groups were sub MOA, but where the groups opened were in elevation.

I am gonna guess that if I load. A little hotter that will tighten up.