.303 Cast bullets tumbling. Need help

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Rkrenz

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Good day CGN

So Im having an issue with my cast bullets in my No. 4 Mk 1. I cant figure out why but my bullets are tumbling at 25m! I believe that under sized bullets aren't my issue because the barrel slugs at .311 and my bullets are sized to .312 and I am not getting any leading.

My load is the lee 185gr .312 mold sized to .312
Bullets are powder coated not gas checked
sitting over top of 13gr of trail boss powder.

Is my powder charge too light?

https://imgur.com/fJmdLMp


https://imgur.com/bakV4qA


My K98 mauser however is shooing very well with cast bullets. At 50m with iron sights I am getting respectable accuracy for a reduced load and have not had any tumbling or leading.

My load is the lee 175gr .324 mold sized to .324
Bullets are powder coated not gas checked
sitting over top of 13gr of trail boss powder.

https://imgur.com/as98BgA


https://imgur.com/o6DrU9S
 
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5 groove or 2 groove? From what I understand the 2 groove barrels may need a harder bullet to engage the rifling properly since there is less to grip on.

I never had any tuck with the LEE bullets but I would suggest trying a Lyman 314299 bullet with gas check. I have never had a problem getting that bullet to shoot well.
 
Third Rail said:
A quick check provided no load data for the 303 at Hodgdon, where did you get the 13 grains from?
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You don't need data right from hodgdon. They tell you how to get your own data.

Fill the case with trailboss to the base of the bullet. DO NOT COMPRESS THE POWDER AT ALL. That is your max. For the min charge take your max and multiply that number by .7 (70%). That number will be your min charge. That works for any cartridge. I have used trailboss in 223, 30-06, 243, 7mm-08 all with the same formulas and different bullet weights.
 
lyman54 said:
Pretty sure you need gas checks on them, that's what causing the key holes. Trail Boss should almost fill the case leaving a small space under the bullet.
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Gas checks should solve the problem. Recently sent 400 rounds down range through a No4 mkll and several Ross rifles.
180 grain gas checked bullets from Bullet Barn .313 dia. Load was 18 grains of H4198. Not one tumbled and the Ross MKlll gave impressive acuracy with this load.
 
Gas checks or you can try a heavier charge. I never had much luck in my 2 gr savage no 4 with trail boss. fine as kind in a no 1. if I use a pc or tumbled lube bullet in my no4 without a gas check it has to be chased with at least 27 gr of h4895. Gas check may be your best option.
 
The shape of the holes makes me suspect that you have a pointed bullet. Generally, flat or round nose bullets shoot better at cast bullet velocities. You may need to get more velocity to get the bullets stable. Bore condition is important and it's possible a thorough cleaning will help. Also, check the muzzle for wear or burrs. Fire lapping may help a slightly rough bore. As with all things related to cast bullets, YMMV.
 
I'll assume that this gun shoots other bullets accurately, i.e. it's not the rifle, but this load combination.

Depending on your OAL, 13.0 grs of Trail Boss should nearly fill the case, and produce 1400-1500 fps. No problem with the load.

You report that there isn't any leading, so that's not the cause of the keyholing, and there's no need for Gas Checks for that reason.

That leaves the "fit" of the bullet. When you slug a barrel, the result is the minimum groove diameter. A reading of 0.311" makes a 0.312" bullet seem ok, but the last or first several inches of a barrel could be slightly greater in diameter. A Gas Check will enable the rear of the bullet to "Bump Up" in diameter, and might solve the keyholing.

It would also be interesting to try a few more bullets without Gas Checks, but unsized. If they fall out of the mold at 0.313" or higher, that might do it right there.
 
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If I had that result, I would clean the barrel chemically and then use RemClean to scrub it.

Then I would try the same load with 1 grain more and 1 grain less, to see if there was an improvement in either direction.

If the bullet was a gas check design, I would try with them, too.

I have not done a lot of lead bullet shooting, but I have had good results shooting the heavy Lee bullet (210gr?) in my Lee Enfields. I used 10 to 15 gr of shotgun powder.
 
I use foam bore cleaners that will remove the copper and carbon without using a copper bore brush. On a milsurp rifle with a frosted and pitted bore the rough bore will "eat" a copper bore brush and give a false copper reading.

Below a No.4 after one shot of foam bore cleaner and letting it soak overnight.

p59rhnP.jpg


Below a brand new Savage button rifled barrel bore scope photo and another reason to use foam bore cleaners. These button rifled barrels will also eat bore brushes.

GpTCke2.jpg


Below a AR15 right after a squirt of foam bore cleaner, what is amazing is the copper from the bullet is turned into a gas and coats the flash suppressor and gas tube. On the AR15 the gas tube can be blasted with Gun Scrubber, carb cleaner, etc. to remove any foam. Just remember that any semi-auto gas system must be flushed out or it will gum things up.

M1BUyQB.jpg


Below the first patch pushed down the bore after the foam did its work.

eIRAnKF.jpg


When switching to cast bullets just keep applying the foam until you no longer see any blue coloration. This will depend on how frosted and pitted the bore is from corrosive primers. It was my experience that Enfield rifles were much better cared for and Mosin's bores were not and can get real ugly and take more time to remove the copper.

Bottom line, the foam bore cleaners will greatly reduce your cleaning rod time spent in the bore and do all the work for you.
 
Andy said:
... 13.0 grs of Trail Boss should nearly fill the case, and produce 1400-1500 fps. No problem with the load.... When you slug a barrel, the result is the minimum groove diameter. A reading of 0.311" makes a 0.312" bullet seem ok, but the last or first several inches of a barrel could be slightly greater in diameter... It would also be interesting to try a few more bullets without Gas Checks, but unsized. If they fall out of the mold at 0.313" or higher, that might do it right there.
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This. ^. I would try the bullet unsized, and see how it works.

Rule of thumb with cast bullets - the larger the bullet is, the greater the accuracy potential will be. The limiting factor is the chamber/leade dimensions, not the bore dimensions. If you can chamber a cast lead bullet then it will shoot. Most LE rifles have generously sized chambers, I normally use .314" or .315" cast bullets in LE 303 rifles. Don't be afraid of using a cast bullet seveal thousandths over groove diameter.

The other rule of thumb with cast bullets is you get better results if you clean the copper and lead deposits before shooting cast. Your barrel will have fewer leading problems and will shoot more accurately if you start with a clean barrel.

lyman54 said:
Pretty sure you need gas checks on them, that's what causing the key holes. Trail Boss should almost fill the case leaving a small space under the bullet.
Click to expand...
shouldn't need gas checks at trail boss velocity, especially if they are powder coated.
 
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