Yes Guys- Size DOES Matter

[sw282]

l have this Smith&Wesson PC 629 Magnum Hunter in 44 Magnum with app 10,000 rounds thru it.

Groups seem to be getting a hair larger now since new. So l decide to do a little measuring.

First l did the throats and found them pretty uniform @ .430''. Per chance l checked my sizing die

and noticed it was .429''. Remembering what l have learned on this site, l ordered a .431'' die.

ln testing only one variable should be changed at a time. Loaded up 18 44 rds @429''. Followed

by 18 boolits sized to .431''. Brass, powder, primer were the same on all 36 loads. l went to the

range yesterday..Fired 18 each @ two different targets.. Range was 25yards... l scored the

targets each.. Score on .431'' boolit fired target had a 20% higher score than the .429''.

thanks guys.


282

[GhostHawk]

Yep, bullet fit is king, but everything matters.

[Catshooter]

Good for you.

Remember, just because it's marked .429 doesn't mean it actually sizes at that measurement. I've been foxed by that before.


Cat

[fatelvis]

Now you should try sizing your boolits at .430". I would bet that would yield the best accuracy with no leading.

[6bg6ga]

And no one mentioned size does matter

[RobS]

Now you should try sizing your boolits at .430". I would bet that would yield the best accuracy with no leading.

Indeed. .430 throats will have a boolit hitting the barrel at .430.

.431 will be sized down to .430 after passing through the throats.

[sw282]

Just a quick update on this thread...Scores up Dramatically due to proper sizing of my boolits..

We had our first IHMSA silh Big Bore match of 2017 Saturday.. Very satisfying to be able to

ring the bell @200 meters shooting a big slow boolit while standing

[TexasGrunt]

Good for you.

Remember, just because it's marked .429 doesn't mean it actually sizes at that measurement. I've been foxed by that before.


Cat

I buy from NOE and don't have that worry.

[Capt. Methane]

Now you should try sizing your boolits at .430". I would bet that would yield the best accuracy with no leading.

This is something that has come up for me recently in .41 Mag. How much is too much oversize? The reason I ask is that the cylinder throats in my S&W are right at .410, as near as I can tell with the five groove rifling the groves are slightly smaller than that-it's pretty tight with a Sierra FPJ passing through the cylinder with slight drag and even a factory .411 LSWC (verified by micrometer) stopping with just the nose protruding from the cylinder.

I'm sizing to .412 and get decent accuracy with soft alloys but as I work up more energetic loads with harder GC boolits can that cause pressure issues or inaccuracy?

I'm also loading for a Henry in .41 and need to slug the chamber area but the muzzle end grooves mic out at .4095...

[gwpercle]

And no one mentioned size does matter

My wife keeps telling me that ! Wonder what she means ?

[sw282]

Sadly, 0ne of our shooters has a 44 Smith w/.434'' throats... Talk about ''Slinging Lead''

He buys .430'' Speer swaged 240gr SWC boolits. Tumble lubes in Alox a couple times..

Then puts them in the freezer before loading

[mdi]

I believe that .431" bullets through a .430" throat won't be a problem, it's just .001" (.0005" on each side). The only problem I've encountered when shooting lead bullets over throat size (+ .002") is lead "spray" on the cylinder face, forcing cone and frame. But I've "customized" my sizing die to give me .431", the same diameter as my 3, 44 Magnum revolvers' cylinder throats. A bit larger is fine, but beware smaller than throat diameter...

I've found many suggestions like "push through", "drop through", "snug fit", "slip fit" to be worthless as they are subjective and not real measurements. It's no big deal to get a micrometer and measure the bullets and know for sure the dimensions you are working with.

[Engineer1911]

My 6" M29 Silhouette and 8-3/8" M629 both have cylinders with 0.433" throats. I have a set of pin gauges 0.251" to 0.500" and a Mitutoyo micrometer with carbide faces. I guess I just identified my root cause for poor accuracy with 0.430" bullets and heavier powder charges. Leading was remarkable.

[Whitespider]

My M29 (5 inch) has .430 throats, the barrel is something a touch less (a barrel slug will drop through the throats with ever-so-slight help).
My Super Blackhawk has .433 throats, the barrel is .4306.
I didn't want to keep two different sized boolits around so I compromised... I use air-cooled WW/2% tin alloy sized .4315, and push them hard enough to (hopefully) bump-up for the Super Blackhawk throats (about 1200 fps). I get zero leading in the M29 and accuracy is very good, what little leading I see in the Super Blackhawk is confined to the forcing cone area and easily manageable, accuracy is also very good.
(Note... it's been a long time since I "printed" groups on paper with either gun so I can't brag about group sizes, but bouncing a beer can at 50 yards, shooting off-hand with a revolver is "very good" accuracy in my world).
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