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How much can you resize a bullet? (Read 249 times)

Skeeter355 Participating Member Offline Posts: 12 Joined: Dec 30^th, 2025	How much can you resize a bullet? Jan 4^th, 2026 at 10:25pm	Print Post
	So slugged my new Shiloh Sharps 40-65 barrel and got a groove measurement of .405. I picked up a SEACO 740 mold and on its initial casting it’s dropping .411 bullets. In most articles I’ve read they’re recommending.001 to .002 over groove. How far would you recommend sizing these bullets? Thanks Skeeter


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marlinguy Frequent Elocutionist Offline Ballards may be weaker, but they sure are neater! Posts: 17536 Location: Oregon Joined: Feb 2^nd, 2009	Re: How much can you resize a bullet? Reply #1 - Jan 5^th, 2026 at 12:31am	Print Post
	I'd agree that .001"-.002" is what I'd want over groove diameter. But that's a long ways from .411" down to .406"-.407" diameter. Leaves the lube grooves shallower, but more important is what happens to the bullet itself swaging it down that far in your lubrisizer! It will likely deform the bullets and might case accuracy issues. You really should never purchase a bullet mold until you have the gun in hand and slug the bore to see what it needs. I prefer not to size bullets at all, but if it was only .001"-.002" I'd do it. More than that and I'd be looking for a proper size mold.

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Schuetzendave Frequent Elocutionist Offline Retired Ex-Shooter Posts: 4194 Location: St. Albert, Alberta Joined: Jan 28^th, 2005	Re: How much can you resize a bullet? Reply #2 - Jan 5^th, 2026 at 12:40am	Print Post
	Are you sure it is .405"? My Shiloh Sharps is the standard .408 and I shoot .410" diameter bullets in it. The measurements between land cuts on a bullet are difficult to measure accurately.


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Skeeter355 Participating Member Offline Posts: 12 Joined: Dec 30^th, 2025	Re: How much can you resize a bullet? Reply #3 - Jan 5^th, 2026 at 7:03am	Print Post
	Yeah I was surprised also about the sizing. I slugged the barrel from the chamber and also the muzzle and both measurements were .405. Once NOE gets their sizers back in stock I’ll get a few more bushings and test out different sizes. A guy over on the Shiloh forums did a small test on oversized and undersized bullets that was interesting. Small sample size and not at different ranges so accuracy at long range wasn’t tested yet.


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Skeeter355 Participating Member Offline Posts: 12 Joined: Dec 30^th, 2025	Re: How much can you resize a bullet? Reply #4 - Jan 5^th, 2026 at 9:22am	Print Post
	I was using calipers to measure but will also need to check with a micrometer. If it’s truly.405 I’m thinking ordering a BACO money in .408 that could be resized down to .407 or .406 or left unsized. Will probably need smaller neck expanders too.


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jhm Frequent Elocutionist Offline Posts: 1929 Location: georgia Joined: Sep 4^th, 2011	Re: How much can you resize a bullet? Reply #5 - Jan 5^th, 2026 at 11:36am	Print Post
	I have owned two Shiloh rifles both 40 cal and the barrels were .408 Shot .410 dia as cast from a RCBS mold using wheel weight. Maybe contact Shiloh about it? JMH


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Skeeter355 Participating Member Offline Posts: 12 Joined: Dec 30^th, 2025	Re: How much can you resize a bullet? Reply #6 - Jan 5^th, 2026 at 12:01pm	Print Post
	Just talked to Shiloh and Lucinda said all their 40 cal rifles should be .408. Will need to reslug and measure again or just assume it’s good and reload as it’s a .408.


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marlinguy Frequent Elocutionist Offline Ballards may be weaker, but they sure are neater! Posts: 17536 Location: Oregon Joined: Feb 2^nd, 2009	Re: How much can you resize a bullet? Reply #7 - Jan 5^th, 2026 at 2:54pm	Print Post
	Skeeter355 wrote on Jan 5^th, 2026 at 9:22am: I was using calipers to measure but will also need to check with a micrometer. If it’s truly.405 I’m thinking ordering a BACO money in .408 that could be resized down to .407 or .406 or left unsized. Will probably need smaller neck expanders too. Is the barrel an odd or even number of lands and grooves. If it's an odd number you might be getting an erroneous measurement.

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