32 ACP barrel bore diameter and twist
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32 ACP barrel bore diameter and twist
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- Posts : 111
Join date : 2018-06-07
Location : Milano
Re: 32 ACP barrel bore diameter and twist
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
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- Posts : 1458
Join date : 2011-06-11
Location : South Prairie, WA 98385
Re: 32 ACP barrel bore diameter and twist
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- Posts : 111
Join date : 2018-06-07
Location : Milano
Re: 32 ACP barrel bore diameter and twist
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)
CraigB5940- Posts : 199
Join date : 2018-01-26
Location : SE PA
Re: 32 ACP barrel bore diameter and twist
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- Posts : 111
Join date : 2018-06-07
Location : Milano
Re: 32 ACP barrel bore diameter and twist
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
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- Posts : 1458
Join date : 2011-06-11
Location : South Prairie, WA 98385
Re: 32 ACP barrel bore diameter and twist
Yes, I understand but how you reload 32 ACP brass in SAAMI specifications with a bullet of .312 and not .308 without deforming problems?
ser2711- Posts : 111
Join date : 2018-06-07
Location : Milano
Re: 32 ACP barrel bore diameter and twist
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
fc60- Posts : 1458
Join date : 2011-06-11
Location : South Prairie, WA 98385
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