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Headspace & Accuracy (Read 5987 times)

Dellet Frequent Elocutionist Offline Posts: 1257 Joined: May 19^th, 2017	Re: Headspace & Accuracy Reply #30 - Apr 22^nd, 2023 at 7:20am	Print Post
	joeb33050 wrote on Apr 22^nd, 2023 at 6:09am: Dellet wrote on Apr 21^st, 2023 at 10:22pm: I am very curious about how this works. In your other thread, the way you increased rim thickness was to move the outside of the rim forward. Above you explained that you seat the bullet on a compressed powder charge and seat the cartridge with the breech block. Seating the bullet into the lands. Headspace is the void between the case head and breech face. NOT QUITE. LOOK UP "HEADSPACE GUN". You have none. The cartridge will not move, you have effectively “headspaced” off the bullet instead of the rim. The only function deforming the rim may serve, would be to keep the case from moving forward with the firing pin strike. With a compressed charge and jammed bullet, you need to either be able to further compress the powder, or drive the bullet deeper into the lands. Or the thicker rim serves no purpose. Partly why I suggested checking if this was actually happening earlier. Am I completely missing something? While you are technically correct, if I lost any more the 1% had I written that in a technical writing class, it would be because the instructor was quite frankly splitting hairs. Much less of an error than in a math class using minus, instead of subtract.


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hepburnman Senior Forum Member Offline Posts: 402 Location: NJ Joined: Mar 22^nd, 2015	Re: Headspace & Accuracy Reply #31 - Apr 22^nd, 2023 at 10:30am	Print Post
	Dellet wrote on Apr 21^st, 2023 at 10:22pm: I am very curious about how this works. In your other thread, the way you increased rim thickness was to move the outside of the rim forward. Above you explained that you seat the bullet on a compressed powder charge and seat the cartridge with the breech block. Seating the bullet into the lands. Headspace is the void between the case head and breech face. You have none. The cartridge will not move, you have effectively “headspaced” off the bullet instead of the rim. The only function deforming the rim may serve, would be to keep the case from moving forward with the firing pin strike. With a compressed charge and jammed bullet, you need to either be able to further compress the powder, or drive the bullet deeper into the lands. Or the thicker rim serves no purpose. Partly why I suggested checking if this was actually happening earlier. Am I completely missing something? One obvious answer might be that the firing pin strike is strong enough to overcome the compressed powder and the bullet, which was initially engaged into the lands, and still moving the case forward, whereby the increased rim thickness is preventing this. I not saying that this is true but I will continue to test this and that. As always, your mileage may vary!


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Dellet Frequent Elocutionist Offline Posts: 1257 Joined: May 19^th, 2017	Re: Headspace & Accuracy Reply #32 - Apr 22^nd, 2023 at 11:11pm	Print Post
	hepburnman wrote on Apr 22^nd, 2023 at 10:30am: Dellet wrote on Apr 21^st, 2023 at 10:22pm: I am very curious about how this works. In your other thread, the way you increased rim thickness was to move the outside of the rim forward. Above you explained that you seat the bullet on a compressed powder charge and seat the cartridge with the breech block. Seating the bullet into the lands. Headspace is the void between the case head and breech face. You have none. The cartridge will not move, you have effectively “headspaced” off the bullet instead of the rim. The only function deforming the rim may serve, would be to keep the case from moving forward with the firing pin strike. With a compressed charge and jammed bullet, you need to either be able to further compress the powder, or drive the bullet deeper into the lands. Or the thicker rim serves no purpose. Partly why I suggested checking if this was actually happening earlier. Am I completely missing something? One obvious answer might be that the firing pin strike is strong enough to overcome the compressed powder and the bullet, which was initially engaged into the lands, and still moving the case forward, whereby the increased rim thickness is preventing this. I not saying that this is true but I will continue to test this and that. As always, your mileage may vary! Yes and no. This is why it gets real complicated, and almost impossible to know for sure. It’s not really about the firing pin being able compress the powder, or seat the bullet deeper. but rather if it’s easier to ignite/crush the primer, than compress the powder charge, or push the whole cartridge and nose of the bullet farther down the bore. You might have different answers with different primers.


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joeb33050 Frequent Elocutionist Offline Posts: 2613 Location: Marathon, FL Joined: Apr 20^th, 2004	Re: Headspace & Accuracy Reply #33 - Apr 23^rd, 2023 at 6:11am	Print Post
	(You need to *Login* or *Register* to view media files and links) Words have meanings.


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Dellet Frequent Elocutionist Offline Posts: 1257 Joined: May 19^th, 2017	Re: Headspace & Accuracy Reply #34 - Apr 23^rd, 2023 at 11:31am	Print Post
	joeb33050 wrote on Apr 23^rd, 2023 at 6:11am: (You need to *Login* or *Register* to view media files and links) Words have meanings. Wrong link to use to support your position. As you said words have meaning Quote: In firearms, headspace is the distance measured from a closed chamber's breech face to the chamber feature that limits the insertion depth of a cartridge placed in it. Used as a verb by firearms designers, headspacing refers to the act of stopping deeper cartridge insertion. The exact part of the cartridge that seats against the limiting chamber feature differs among cartridge and gun designs.[1] Bottleneck rifle cartridges headspace on their case shoulders; rimmed cartridges headspace on the forward surfaces of their case rims; belted cartridges headspace on the forward surfaces of their case belts; rimless pistol cartridges headspace on their case mouths. Under the above definition, by omitting the word “case”, that is used in the SAAMI definition, I am correct. Which technically speaking, I am not. You, are guilty of spreading disinformation The problem with the “words” here, is that there is no description in the definitions of headspace for a cartridge that seats in the chamber on the bullet. Which is the case here. Using the proper term of “head clearance”, the answer is still zero. Quote: HEAD CLEARANCE The distance between the head of a fully seated cartridge or shell and the face of the breech bolt when the action is in the closed position. Commonly confused with headspace. I beg the forums forgiveness.


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hepburnman Senior Forum Member Offline Posts: 402 Location: NJ Joined: Mar 22^nd, 2015	Re: Headspace & Accuracy Reply #35 - Apr 23^rd, 2023 at 11:51am	Print Post
	I do like the term head clearance which I reduced to a minimum in additional test reloads


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