Hunting velocity issues

[Hook]

A few months ago, I decided to develop cast bullet hunting loads for a few of my rifles. I cast 30 cal and 458 cal bullets to use in 30.06, 308, 30-30, 30-40, and 45-70. All bullets are gas checked and powder coated. Early work was for plinking loads and they all worked beautifully. Then I started pushing velocities up to the 2000 fps +/- range on the 30 cals. Bullet selected was the RCBS 180 gr FN because of it's healthy meplat.

The 30-30 (Winchester M54) and the 308 (Rem M600) did beautifully, 2050 fps for the 30-30 and 1950 fps for the 308. Accuracy is well within acceptable boundaries for the range I might shoot a whitetail. The 30-40 does as well as can be expected with it's peep sight and my 71 yr old eyes.

The 30.06, a sporterized 03A3 with a WWII 4 groove bbl, refuses to give any kind of consistent accuracy at the desired velocity. I have tried a half dozen different powders recommended for that caliber and velocity and just can't get there. I tried again this morning with two more loadings and I'd get 2 shots kinda sorta OK and then 2 or 3 scattered out 3-5 inches.

Got to wondering if my rifle and/or scope had gone on the fritz, so I grabbed a 50 round box of the plinkers loaded 2-3 months ago. It is the RCBS bullet over 16 gr of 2400, straight out of Harris' "The Load". I fired 9 shots at a steady pace over about a 10 minute period. The first 5 went into a little over an inch and the other 4 into 1.3". Obviously nothing wrong with the rifle.





Any ideas why this bullet does so well at plinking and hunting velocities in 2 calibers and so well with plinking but lousy with hunting velocity with a third caliber. I just don't understand. Do some barrels just hate higher velocities with cast? BTW, this 03A3 has always shot well with jacketed. In fact, I made my longest ever kill with it a few years ago, about 325 yards.

[kungfustyle]

So you did a ladder work up load for the 06, yes? It may be the hardness of the bullet. Is the bbl longer on the 06? Does it slug out the same? As a general rule if a barrel will shoot jacketed, it will shoot cast. Is the bullet a gas check design? What weight? May want to go heavier, harder, wider and gas checked to get to that velocity. It is completely doable.

[Tripplebeards]

How is the rifle bedded? Did you clean all the copper fouling out of it? It took my three days of soaking to clean all the copper fouling out of my 1941 long branch.

[versa-06]

Maybe twist rate, The Win .30-30 probably 1:12 twist Rem. 600 maybe 1:12 Most 30-06's 1:10 I get my best hunting loads out of my 30-06's RCBS 30-180 203gr lubed & checked with 23-24 gr IMR SR4759 depending on the length of the barrel & priner used. My acceptable velocity vs accuracy in a 1:10 twist is usually around 1750 fps due to soft alloy.

[bmortell]

my 10 twist 30-06 could miss a refrigerator at 50 yds if its just slightly over the 2k area. really doesnt like it

but ya i just be happy with 1950 ish. if you want more power put a 220gr at 1950. which is what i do for 30-06 deer guns

[Hook]

Well, my guess is that the last two posters have hit the nail on the head. I never would'a thunk that a WWII bbl would have an issue because of it's twist rate. That may very well be the reason it shoots so dang well at lower velocities and not so good at higher. The fact that the 308 and 30-30 would, and it wouldn't, really messed with my head.

So, what I am going to do is start gradually raising the velocity and see where I can get to before the accuracy goes to pot. I can live with versa's 1750ish range if I have to because I am running a pretty soft alloy that should still perform well at that level. I really wanted all three to have about the same velocity so that I could use the same zero and trajectory for hunting purposes, but what the heck....it ain't rocket science at the ranges I'll be confined to!

Thanks to all for your comments!

[popper]

Probably alloy in the 06 twist. 180 is is a little heavy for 1:10. Try RL15?

[Hook]

Yep, looks like the twist rate is the culprit! This morning, I ran 3 rounds each of 18 and 20 grains of 2400 over the chrono. They averaged 1600 and 1700 fps. FYI, my barrel was cut to 21" at some point, so my velocities run lower. After that, I tried 21 grains and got a 1770 fps avg.

Then I loaded a batch with 21 grains and went across the creek to my range. Here is the result:




You can see that the load was wanting to group well, but it kept having flyers. So, I went back the the shop and loaded another batch with 20 grains. Six were loaded in LC53 brass and 3 in XHP. The loads in the XHP were difficult to chamber, it seems the neck thickness of that brass combined with the .311 bullet caused the neck diameter to be a tight fit in the chamber's neck. Just in case that made a difference in POI, I shot them into different targets. Here is the LC target:




The XHP target:







As you can see, I got a good, round group with no flyers. I needn't have worried about about the HXP brass, because those 3 went into the same POI. I cut that target out and superimposed it over the LC target and traced the holes onto it. Two of those bullets would have nestled within the tight clump and one would have very slightly opened the total group a coupe of tenths. You can see the ink circles where the XHP loads would have landed in the LC target.

No question that I have reached the upper velocity limit with this bullet in this rifle, at least with 2400. I would have prefered to get a couple hundred more fps, but with this flat point and it's soft alloy, I think it'll get'r'dun! I may experiment next year to see if I can improve on it. But, for now, I just loaded 30 rounds using the soft alloy, moved the POI to 2.75" high, and am good to go. Just have to wait for opener.

Thanks again for the help.

[white eagle]

alot of people make this mistake of thinking that you can get jacketed velocities out of cast boolits
sometimes you can but it depends on the cartridge like the 358 win for example
for me and my rifle and alloy I can get approximately the same velocity for both
it can be a whole lot of trial and error but that is what makes the game intriguing

[Larry Gibson]

Hook

RPM is the problem child here. You have just explained the results of the RPM Threshold. Yeah, I know, alot think it's bunk but you've just found it isn't.

"The 30-30 (Winchester M54) and the 308 (Rem M600) did beautifully, 2050 fps for the 30-30 and 1950 fps for the 308."

The M54 Winchester has a 12" twist barrel so at 2050 fps the cast bullet is well under the RPM Threshold for it, hence the good accuracy. The M600 Remington 308W has a 10" twist but at 1950 fps the cast bullet is just at the RPM Threshold w/o surpassing it, hence the good accuracy.

As you've found with your 30-06 with the 21" barrel, once you dropped the velocity back down to what is under or at the RPM Threshold with 2400 powder under the 180 gr cast bullet accuracy improved substantially.

With that weight bullet I would suggest a change to a slower burning powder such as 4895 for use in all the cartridges mentioned. As examples I've used 4895 under a 178 gr cast bullet in the 30-30, the 308W and the 30-06. The 4895 powder can push that weight cast bullet to the RPM Threshold (1950 and 2330 fps +/- fps) out of 12 and 10" twist barrels.

[swheeler]

"All bullets are gas checked and powder coated." Seems to act just like conventional grease lubed bullets of similar hardness, maybe powder coat is nothing more than a lube

[farmbif]

twist rate vs bullet weight and speed, how would I figure out best bullet weight to get max speed with the 1:16 twist 35 Whelen . ive got 3 molds that are applicable
200 grain, 220 and 250 which would be best in attempting max velocity with accuracy?

[fcvan]

Powder coating is a bit more than lube in the barrel, it is also useful shielding from the trip to the chamber in semi automatic rifles. Example: I started out shooting a Lyman C225-55 RF, designed for a gas check. When shooting lubed, the boolit took a beating from the feed ramp. It was cycling at 2250 fps rather accurately, but frequent fliers. When shooting PCd, the groups tightened to 1" ish groups at 100 yards. I would shoot, then remove the cartridge chambered under normal shooting conditions. The lubed boolit showed nose deformation, the PCd boolit did not.

Now, I shoot an NOE 225-62 RN, designed for powder coating without a gas check. I get full cycling from a 1-9" AR 15, a 1-10" Mini 14, at 2250 fps. I also have a single shot 24" H&R 1871 Handi Rifle that gives 2450 fps with the same load. That cartridge of course does not take a beating when chambered and groups slightly better, partly because of the longer barrel, partly because no gas is lost to an operating system.

I need to download this cartridge to see if I am over rotating the boolit. Since I PC, I can use a different color to differentiate the single shot loads from the semi-auto loads. That and I also put semi loads in stripper clips with a printed load spec, and the 'accuracy' loads in boxes. It will just take a range day when I take my portable reloading station to the range and build 5, shoot 5, and ladder down (or up) to a sweet spot the rifle likes. I will also try loads with the Lyman boolit and gas checks as I have 10 pounds of the 55 grain boolits, and 20 lbs of the 62 grain boolit, all have already been PCd, from a 50/50 COWW/pure lead mix.

PC is a lube substitute with a little more. Lubed lead was a relative clean shooter, PC has always shown 'factory new shine.' That, and I don't need to harden up for accuracy, current alloy gives me devastating performance on rodents and pests, and murderous on tin cans. I mostly shoot standing without a rest or shooting sticks. The only bench testing was done when first shooting a new rifle, the Mini 14 was well used when I got it. I am happy with the performance. Tin cans, are not very pleased.

[Hook]

Larry, I tried several different powders attempting to reach a higher, hunting velocity, including H4895. I think my problem hinges around just jumping from the accurate plinking loads up to 2000 +/- fps. It worked for the 30-30 and 308....didn't for the 30.06. I backed off the 2400 loads and walked up to a medium velocity that works well, even if it's not as fast as desired. I suspect that the same can be done with the slower powders, maybe resulting in higher velocities than with 2400. That will be a project for after this season. The 1700 fps loads I've put together will suffice for now with careful shot selection.

Thanks again to all for your comments and suggestions.

[Larry Gibson]

twist rate vs bullet weight and speed, how would I figure out best bullet weight to get max speed with the 1:16 twist 35 Whelen . ive got 3 molds that are applicable
200 grain, 220 and 250 which would be best in attempting max velocity with accuracy?

You will, no doubt, "max out" with any of those bullets in the 16" twist barrel because of recoil and that the RPM Threshold for a 16" twist will be in the 2900 - 3100 fps range. When you get into the higher velocity range for cast bullets [naked GC'd and lubed ones] how high the velocity gets while maintaining the accuracy you want depends on other factors also. The major factors are; how well you can shoot under the recoil, quality of the alloy, quality of the cast bullet, design of the bullet, consistent weight of the cast bullet, proper GC seating, slower burning powder used, quality of the reload itself, etc. Go for it, good luck and keep us informed(?).

[GregLaROCHE]

Softer, heavier and slower boolits in my opinion, are better than hard high velocity, for harvesting meat. Keep this in mind while developing a hunting load.

[Larry Gibson]

Larry, I tried several different powders attempting to reach a higher, hunting velocity, including H4895. I think my problem hinges around just jumping from the accurate plinking loads up to 2000 +/- fps. It worked for the 30-30 and 308....didn't for the 30.06. I backed off the 2400 loads and walked up to a medium velocity that works well, even if it's not as fast as desired. I suspect that the same can be done with the slower powders, maybe resulting in higher velocities than with 2400. That will be a project for after this season. The 1700 fps loads I've put together will suffice for now with careful shot selection.

Thanks again to all for your comments and suggestions.

The reason it didn't work in the '06 at 2000 fps is that velocity was/is above the PM Threshold for the bullet/load used. The RPM Threshold in the 10" twist '06 is going to be about 1950 fps. Switching to 4895 with a dacron filler [the slower burning powder than 2400 will give a gentler "push" on the bullet] and working up to 1850 - 1950 fps should still give you the same accuracy level as the 30-30 and the 308W. However, you seem satisfied with the load you're using for the time being in the '06 so give it a try. Good luck hunting with all three, they should do the trick.