Troubles????

Hi Everyone,

I wasn't quite sure where to post this, but here it is. Keyholing issue. I am using a Lyman 311466 mold. This mold, for whatever reason drops boolits at .315-.316. What I am doing is working on a load for my 303 Brit. I decided to try some tumbled lubed with 45/45/10, and some powder coated. My starting load is 13 grains of Unique. My 303, as best I can tell slugs at .315. ( it's a 5 groove, so kinda hard to be real accurate) I decided to try some tumble lubed as cast and seated a gas check. I powder coated some and gas checked and sized them to .314. ( it was the closest size I had) After firing them at 25 yards, on separate targets, 10 rounds each, six of the tumble lubed boolits went through the target sideways. All ten of the powder coated boolits were normal, and grouped quite well. So it seems, why worry, just bake them and shoot them, right? Probably will. But I'm just trying to figure out what may have caused the t/l boolits to perform so erratically? Thanks in advance for giving this a look, and any thoughts on the matter.

Have you slugged the bore? The PC may be increasing the diameter enough for the rifling to get a good grip.

Are you seating the boolits to touch the lands?
If seated so there is a jump to the lands, there is more of a risk of a crooked launch.
As to why you didn't see keyholes with PC, Maybe the PC has increased the nose size, so that batch is less likely to have a crooked launch.

First step should always be to slug the bore, before you start making boolits. That bore could be really worn. Shooting lead enables you to make up the difference in the wear.

Barrel condition, which is not mentioned, can often be a factor with older military rifles. The throat can be worn by erosion due to burning powder, or just worn by a lot of bullets having passed through the barrel. The muzzle can be worn due to careless and aggressive cleaning. You might consider slugging the entire barrel, which it sounds like you have already done. That will give you the minimum diameters in the barrel. Try slugging the area a few inches before the end of the muzzle to see if that is larger than the middle of the barrel. Slug the area an inch or so in front of the chamber to see what you have there. If you have a barrel with measurements being loose-tight-loose, that might be part of your problem.

I was helping a friend with a rifle with similar barrel conditions. It would not shoot reduced loads at all, without tumbling. I used the same cast bullet with beginning load data from the RCBS Cast Bullet Manual and the rifle shot as accurately as it did with jacketed loads. The book data for H-380 which is a rifle powder and gave a push rather than the impact of the fast pistol powder. I also used the CF Ventures soft wax gas check which sealed around the bullet base when the barrel loosened near the muzzle. That seems to have eliminated both leading, and tumbling. Your results might be different.

The 303 British was originally loaded with black powder in 1888. Black powder (but not substitutes) can upset soft lead bullets to fill the rifling. As-cast TL bullets can be finger lubed with T/C Bore Butter. Soft lead may cast slightly larger than a harder alloy as well.

Of the British rifles I've had , only one of them a number four mark two measured .314" . Everything else went all the way to .319" .

For the stubby bullet you are using , paper patch the bullet until it just barely slides into a fired case . That diameter is likely going to shoot well .

Jack

Sounds like undersize bullets. The powder coating is probably just bring them to marginal diameter.

Quote:

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Originally Posted by Jack Stanley

Of the British rifles I've had , only one of them a number four mark two measured .314" . Everything else went all the way to .319" .

For the stubby bullet you are using , paper patch the bullet until it just barely slides into a fired case . That diameter is likely going to shoot well .

Jack

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I was expecting these kinds of measurements with a 1942 No4 MKII BSA ( Birmingham Small Arms) no. 490 ... but when I slugged the bore ... for the third time and still got the following ... .303" bore + .004" groove + .004" groove = .311" !!! Now if I add .001" that = .312 " for a proper boolit dia.
Who has ever heard of a British Enfield that takes a .312" Cast Boolit ????
They are all supposed to be .314" to .319" !!!
Do you know how hard it is to find a 303 mould that's .312" ... Lee had them in stock , but that was a few years ago .
My oversized bore troubles never happened ... I was sorta lost the .312" size worked perfectly with Unique and Red Dot ... it was just too easy !
Gary