Home Forums Reloading Big Game Rifles Partitions and bullet jump

I am about to start developing a new load my .270WCF

I will be using 130gr Partitions and IMR7828SSC with CCI-BR2 as I have a good supply of both at hand.

Do Partitions normally respond with better accuracy to a particular amount of jump to touch the lands?

Or would you just start almost kissing them and experiment with small OAL reductions?

Thanks!

I have found in my rifles 30 thou off the lands works best for me. At 20 thou always seems to be a flyer. 10 thou looked more like a shotgun pattern. Of course every rifle is different.

I seem to get the best results with Partitions anywhere from 0.025" to 0.030" off the lands. I do believe that there can be multiple sweet spots as you seat deeper, though...at least with some bullets.

I will load 4 each with 57,5-58,5-59,5 gr of powder, all of them with a 0,03" jump and see how they go.

Thank You!

This is normal.
Whenever 2 are close and the 3rd out of the group, seating deeper usually brings it into the group.
For thin barrels, an 1/8th of a turn on the seating die and for medium weights, perhaps a 1/4 turn to get the same results and usually a repeat or 2 is also necessary.
John

I start out at factory length, if I get 1” or smaller groups, I’m good to go. If I don’t, The I will experiment with length. I’m just a hunter.

Here's my two cents, I'd start by loading the bullet as far out as the throat and or magazine box will allow. If groups are to your liking stop, if not begin seating bullet a little deeper etc. You didn't ask, but I've shot several .270's and none gave top accuracy or velocity with IMR7828. and the 130gr bullet.

I like H 4831sc in my 270. Found the best combo of accuracy and velocity with it.

+1

I usually load them as far out as I can and still have them feed through the magazine. Backing off has never worked for me...

Again, I hate to do it because I'm answering a question you didn't ask but I have to agree with the two previous posters. It's hard to beat H4831sc with the 130gr Nosler Partition in the 270 Win. It's a classic and for good reasons.

As with other bullets, no rules apply with the Partition. I've used them in calibers from .22 to 30 in many different cartridges. Some need long seating, others short, some in between.

Though perfect for hunting, I've always thought of the Partition as a strange bullet. Some rifles display incredible accuracy with Partitions. In others, accuracy is beyond terrible. I would guess 50% of the rifles I've tried Partitions in did not shoot them well. In such situations, I've found a Barnes TSX BT will usually remedy the matter.

hanco,
I am just a hunter, too. I do not know what is the factory length, can you please tell? If I do not get the accuracy I am looking for -4 shots under 1,2" at 100 meters or 110 yds- with a 0,03" that could be my second try.

super T,
Rifle is a BlaserK95 single shot, so there is no limiting factor in COL. I can load them as far out as I wish until they touch the lands.
Regarding 7828SSC we shall see... I have 3lbs at hand and will try with it before anything else. According to their online data source, velocity should right up there. I am using Norma cases and they have a few extra gr of capacity, so I should be able to stuff enough 7828SSC inside, I guess. Acuracy is another thing, but we shall see.

lotech,
We have an enormous choice of bullets. This gun is super accurate with Berger's 140gr Hybrid Hunting and H4831 but theres something classy and classic about a .270 and a 130gr Partition I want to try. Even more classic would be with H4831 but I do not have much left and want to save it for the Bergers.



will report on my findings before the end of the day. rgds. to all.

270 maximum over all length 3.340

7STW,
In my particular gun, a 130gr Partition will ber kissing the lands at 3.33"


I just got back from the shooting range and accuracy was so-so... Best 4 shot group at 100 meters -ca. 110yds.- came at 59,3gr/7828SSC/CCI-Br2/3097 and measured 1.15"

For my style of hunting that is enough, but I will play a little with the seating depth and maybe increase the load towards 3,100fps and see what I get.

There seems to be a pattern in the sense that the higher loads produce tighter groups than the lighter ones so it might be worth exploring.

I woul also like to ask if there is a more or less standard pet load with H4831 and the 130gr Partition bullet in the .270...? After all, I might give them a try too

Hello chamois

In my Win Model 70 I run the standard Jack O Connor load of 60 grains of H 4831sc. I would start at 57 gr and work up one grain at a time to find the pressure point. At 60 grains there are no pressure signs and accuracy is excellent in my rifle. I also use the Winchester Large Rifle Primer as I have found with that much slow burning powder the hotter primer seem to work best.

I've used 7828 in a couple of .270s with at least as good accuracy (probably better) as the same rifles produced with H4831. I have heard it called one of the most under appreciated powders. I keep it for the .270s and also for when a friend wants to come by and load for a magnum. As a side note I find H4831 works well for me in heavy (178 grain) .30-06 loads. As far as cartridge over all length I believe in trying as long and close to the lands as reasonably possible and then backing down if needed.

Chamois- I have seen very good performance, accuracy-wise with the 130 Partition in a couple of .270s, though I have never killed game with that bullet for some reason. Like others, I've found H4350 or H4831 work fine, though one seems to always slightly edge out the other in accuracy from a particular rifle.

A few years ago, I tried Reloder 19 with a number of bullets including the 130 Partition. Generally, Reloder 19 proved a bit more accurate than H4350 or H4831 with most bullets. Rifle was a new Cooper, and results from one rifle prove nothing; just thought it interesting. To simplify matters, however, I'll stay with the Hodgdon powders as I use very little Reloder 19 in anything else.

There's far more difference due to variations in individual rifle throats than the bullet loaded, the reason advice on seating depth doesn't always work for all rifles and bullets.

One of the best pieces of advice on loading Partitions came from Gail Root, for many years the head bullet designer for Nosler. He said that if they didn't shoot very well in a particular rifle to try a slightly faster-burning powder, which "bumped up" the rear core to fit a slightly loose throat and/or bore better. I've also found Partitions often respond to a little more slow-burning powder, probably for the same reason.

Partitions also can be more sensitive to being seated a little crooked than other bullets, perhaps because the rear core gets deformed slightly when the bullets aren't seated straight, both in the cartridge neck and when it starts down the barrel.

But a worn throat may simply refuse to shoot Partitions well, no matter what you try. I have a .257 Roberts that shot 100-grain Partition extremely well 25 years ago, but its barrel has seen enough use since to result in visible throat-wear, as seen through my bore-scope. It simply will not shoot 100-grain Partitions the way it used to--but will shoot 100-grain Ballistic Tips very well.

I will try some COL tweaking with 7828, and whichever produces the best accuracy I will try with H4831 and H4350. Maybe the slightly faster-burning powder works for this particular rifle.

It will take some time but I will eventually report in whatever results I get.

Thank you everybody for your contributions.