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32 ACP barrel bore diameter and twist

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32 ACP barrel bore diameter and twist Empty 32 ACP barrel bore diameter and twist

Post by ser2711 Thu Apr 07, 2022 9:07 am

What is the real bore diameter and twist now of .32 ACP when the Lothar Walther barrel blank are the same of 7,65 mm Para (.308) and Twist 250mm(9.8 inches)?...Also bullets Fiocchi diameter is .308 in factory 32 AUTO FMJ 73 gr.

ser2711

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Join date : 2018-06-07

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Post by fc60 Thu Apr 07, 2022 11:42 am

Greetings,

32ACP bore dimensions vary all over the "rainbow".

Look up the CIP specifications and note the diameter tolerances. (7,62 Browning)

https://bobp.cip-bobp.org/uploads/tdcc/tab-iv/tabivcal-en-page12.pdf

Then, check the SAAMI specifications and tolerances. (32 Auto)

https://saami.org/wp-content/uploads/2019/02/ANSI-SAAMI-Z299.3-CFP-and-R-Approved-2015-12-14-Posting-Copy.pdf

Cheers,

Dave
fc60
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Post by ser2711 Fri Apr 08, 2022 3:07 am

So the 32 ACP use on Pardini is not the .32 ACP with his original size of 308..and different barrel twist (32 wadcutter)

ser2711

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Post by CraigB5940 Fri Apr 08, 2022 8:14 am

You have to slug your bore. My Pardini 32 ACP slugged at 0.3125 bore diameter. You can call Pardini USA and ask them what twist they use and what the factory tolerance is for bore diameter.


Last edited by CraigB5940 on Fri Apr 08, 2022 8:15 am; edited 1 time in total (Reason for editing : typo)

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Post by ser2711 Fri Apr 08, 2022 9:39 am

I am in Italy and I know the size .3125 and the twist (16") of Pardini barrel are the same as 32 S.W wadcutter only chambered in 32 acp who sould be .308 twist 9.8"

ser2711

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Post by fc60 Fri Apr 08, 2022 11:26 am

Greetings,

Pardini 32 ACP barrels are 0.314" with a 0.312" choke at the muzzle.

Twist is 1:450mm

Curious, the barrel is the same for the 32 Long and 32 ACP. The chamber reamer determines how it will be used.

Also, the Pardini 32 ACP is NOT A SAAMI chamber. It is a Pardini proprietary development. The cartridge head spaces on the case mouth, NOT THE RIM.

Cheers,

Dave
fc60
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Post by ser2711 Sat Apr 09, 2022 4:34 am

Yes, I understand but how you reload 32 ACP brass in SAAMI specifications  with a bullet of .312 and not .308 without deforming problems?

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Post by fc60 Sat Apr 09, 2022 3:33 pm

ser2711 wrote:Yes, I understand but how you reload 32 ACP brass in SAAMI specifications  with a bullet of .312 and not .308 without deforming problems?

This is a challenge addressed by the reloader.

We can select brands of brass based on wall thickness and uniformity. I prefer R-P brass for my 0.314" bullet loading.

Bullets need to be matched to fit the barrel groove diameter.

With Lead bullets, a 0.314" diameter works well in the Pardini barrels. Bullets with small diameters tend to have larger group sizes. Some quite bad.

In the case of Jacketed bullets, 0.312" is the largest I have seen marketed. i.e. Hornady 85 grain 0.312". These shoot X-ring at 50 yards in the factory Pardini barrels. Yes, the bullet is 0.002" smaller than the groove diameter of 0.314"; but, test targets say it works.

Also, you cannot go to the local Gun Shop and ask for 32 ACP Match ammo. It does not exist. All the loadings are for Personal Defense. True, you might happen on to a lot of ammo that shoots X-ring. The challenge is will the next lot of ammo shoot as well?

Do recall that the 32 ACP is a Personal Defense cartridge/weapon. Not a precision Target offering.

Pardini sorted out a way to make their HP conversions accurate at 50 yards in 32 ACP.

Cheers,

Dave
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