Whats the maximum oversize for the boe riding shank of a boolit?

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drone posted this 4 weeks ago

I have some commercial boolits hardcast for the 303 british.

They are gas checked and I've lubed them with liquid alox. They have been sized to 309 but whilst checking them with my micrometer I noticed that the bore riding section ahead of the 309 diameter was 0.302", the bore of my 308 for which these are destined, is 0.300".

s this too much bearing in mind I have nothing that can resixe the front end only of the boolit.

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Idahocaster posted this 4 weeks ago

I find that having a nose that will engage the rifling a bit helps with accuracy. The trick is will they chamber? Load a dummy cartridge with one of those bullets and see if it will chamber smoothly without pushing the bullet back into the case. If it will, load some up and give then a try!

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porthos posted this 4 weeks ago

i think that the .309 size might be 3 or 4 thousands too small.

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Aaron posted this 4 weeks ago

Load a dummy round and see what happens.

With rifle in hand, I confidently go forth into the darkness.

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drone posted this 4 weeks ago

Dummy rounds exhibit slight drag at the closing end of the lever stroke, engrave by rifling for about 0.02" as far as I can estimate.

Meanwhile I had a eureka moment, doesn't really matter about the size as following along behind is a 0.309" diameter shank.

I worried about pressure but I try to select my powders to provide the minimum pressure peak (on paper I must say).

Gun is a 308 Browning BLR 81 and it's the BLR I'm most concerned with though as I need it to be reliably accurate out to 200 yards. 

My knowledgeable club mates tell me that to seat the bullet into the leade isn't always a bad thing, sometimes accuracy improves.

Next step is to field test the load I've settled on for accuracy.

Dummy bullets cycle fine with the last few degrees of lever throw stiffening up a bit and the rifling clearly engraved on the bore riding shank. Bullets were fairly heavily crimped into the groove so bullets didn't set back. Extraction was OK.

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Idahocaster posted this 4 weeks ago

Load a few and give them a try! My rifles tend to like having the bullet right at or engraved into the rifling.

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drone posted this 4 weeks ago

 Dummy RoundBoolit weight

I load it as a 180 grain boolit using 20 grains of 2400. I've reduced the OAL to what you see, which is still longer than Lymans Minimum oal for such a load. I'll be using them this weekend to see how they function.

Dummy round feeds and ejects through the BLR OK.

Just to be clear, I have two sets of loads, one with the OAL of 2.795 +/- a bit and the dummy OAL as above which I have yet to load. 

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Aaron posted this 4 weeks ago

I'll be curious to see how this works for you. I suspect there may be a leading issue so keep an eye out for that.

 

With rifle in hand, I confidently go forth into the darkness.

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drone posted this 4 weeks ago

I have a new to me Savage 99 in 22 hi power that I'll be range checking this weekend, also my win 94 needs some exercise, I'll be checking those boolits out on the 3rd saturday of june ( my club has a range booked the 1st and 3rd saturdays of each month) and I'll revert after that.

 

Many thanks to all for your interest, I appreciate it.

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linoww posted this 4 weeks ago

I've shot quite oversized bullets for bore and groove dimensions with success quiet often. I worry about throat fit first.i try to use the largest diameter that fills the throat. an example is a 7.5 Swiss Martini with the GP90 chamber for paperpatch bullets.The throat starts at about .330 in front on the chamber. The bore and groove is .307 x .296 (roughly). I shoot heeled(stop ring ) bullets meant for the 8.15x46r (.322 ) or breech seat a 32-40 bullet I machined a .328 base band on.

 

Another fellow on the ASSRA forum is shooting a similar Martini with oversized bullets with great results. 

"if it was easy we'd let women do it" don't tell my wife I said that!

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drone posted this 3 weeks ago

I'll be shooting the 308 this coming weekend, 8th june 2024 so will revert after that.

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Idahocaster posted this 3 weeks ago

I'm interested to see how it works out for you!

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drone posted this 3 weeks ago

I can confirm that the reduction in OAL solved the issue, I was shooting silhouette targets and found that at the velocity of these, 1600 fps give or take, trajectory is rainbow like and after 150 yards the wind really moved the cast boolits around.

I'm reasonably happy but now I'll have to increase the muzzle velocity to around 1900 - 2000 fps to improve the 200 yards accuracy.

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