Lee Loader

With the hog-killing as of late and only two rounds of ammunition left, it is time to reload a batch of ammo. Here is what has been shooting so well with my scout rifle.



I wanted to see what changes are made to velocity and MOA when the case is topped off to 100% of the case capacity with the bullet seated using the BPI Buffer Filler.



Notice in the TMT cartridge drawing that the "airspace" above the powder charge has been filled with the BPI product.



As a note, I'm back to using the Collet Dies on the Challenger press, and I'm not having any issue with the brass. Previously, with the die on the Classic Turret, I was getting some type of "bump" applied to the case between the shoulder and web that would not allow the cartridge to chamber. I've had precisely the same issue with the Collet/Turret with the 300 Savage. The die's instructions require a different setup for each press, but I set them up correctly as the detail indicated.

The Auto Drum sure makes reloading easy. I have specific drums labeled for my "inventory" loads that are kept with the die sets — nothing to getting set up. The work is done before you know it.

Always been a fan of PRVI bullets. Have you tried IMR 3031? I must dig out my 303B notes. I seem to recall that it was a full case load but I may be mistaken. I was trying to find a powder equal to that used when the military stopped using cordite in the MK VIIz round. I believe it was a French powder. I think I made a post on the subject here or perhaps on a collectibles forum.

Edit: Found it.

https://www.lee-loader.com/viewtopic.ph ... 03b#p26487

Thanks for the reference Macd, I remember the topic.

I don't have any IMR rifle powder, the two Hodgdon powders that I've narrowed the 303 British down to is Hybrid 100V and Varget. Without a doubt, the best MOA performance I've had (less than 1 MOA at 100 yards for 5-shot strings) is with these two, but I've tested BL-C(2), H322, H335, H4198, and H4895. I think Hybrid and Varget have outperformed the others because they have the highest case fill of the powders tested for a given pressure. I've been shooting the Varget, but I think Hybrid might have the best MOA and FPS performance.

My initial shooting was with the cartridge at an overall length of 3.070". I left the Hybrid loads at that length as a given and slowly started reducing the overall length of the Varget loads. As I reduced COAL, I had to reduce the Varget charge slightly to avoid stiff extraction. The funny thing was that as the bullet was ever so slightly seated deeper, the max that would avoid stiff extraction remained at 92% of the useful case capacity.

For those that might not understand that concept, a case filled to the neck with powder, but without a bullet being seated, is at 100% of its capacity. As you introduce the bullet and seat it, the capacity displacement creates a change in the usable case capacity. The deeper the bullet is seated, the smaller the available capacity becomes. As I seated the bullet deeper and continued to match the 92% fill, I remained clear of stiff extraction.

With the Varget, what I'm trying to do with the filler is see if it puts some advantage over what's been shot with that powder without getting me back into the stiff extraction. Granted, the Varget performance has been excellent, really good, as the best string to date has been .710 MOA at 100-yards.

As I start the OAL reduction of the Hybrid from 3.070 to the 2.960, the COAL that the PPU bullet seems to like (and matches the cannelure), the powder charge will simply be reduced to maintain the 100% fill.

I've said it before, but will again; the 303 British has been the toughest cartridge I've worked with to find what works. I'm up to 42 different efforts and will gain a few more as the final work with the Hybrid 100V continues.

Ranch Dog wrote: The Auto Drum sure makes reloading easy. I have specific drums labeled for my "inventory" loads that are kept with the die sets — nothing to getting set up. The work is done before you know it.

As usual RD's posts always get my grey matter going. I have been looking at IMR's newest offerings and wonder if 4166 and 4451 might be worth a try for the 303B. 4166 is just above 4064 in burn rate and 4451 is just below 4350. 4451 should also work well in 6.5x55 and 7.5x55.

Macd wrote:As usual RD's posts always get my grey matter going. I have been looking at IMR's newest offerings and wonder if 4166 and 4451 might be worth a try for the 303B. 4166 is just above 4064 in burn rate and 4451 is just below 4350. 4451 should also work well in 6.5x55 and 7.5x55.

Do you know anything about the bulk density of the powder (or VMD)?

No not at this time. Trying to find that out.

hERE YOU ARE.

https://leeprecision.com/files/instruct/VMD.pdf

Nice, an updated list.

The specific gravity of IMR 4166 is .846 and 4451 is .907. None of the numbers speaks of the volatility of the powder just the fill. The latter, 4451, probably has a better chance of filling the case.

I'm sure you have seen Hodgdon's IMR data.

Yes I looked at the loads listed. I find it of interest that 4451 at the max is compressed. This is one of the things that intrigues me.