No4 & No5 Bolt Head Sizes (Update) |
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Shamu
Admin Group Logo Designer / Donating Member Joined: April 25 2007 Location: MD, USA. Status: Offline Points: 17603 |
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A lot of modern ammo is thin walled & has thin rims as well. Can you get Prvi Partizan brand there? If so switch to it, or if you can find it Greek HXP stamped brass. Its Way way closer to spec.
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Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)
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Goosic
Senior Member Joined: September 12 2017 Location: Phoenix Arizona Status: Offline Points: 8792 |
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Gerrit. You mentioned that you are using Hornady brass. I would consider something else such as what Shamu suggests. I purchased 200 Hornady cases awhile back. Loaded everyone to exacting specifications,starting 1 grain above minimum charge from my data sheets. Fired everyone from the same rifle that has correct headspacing,no chamber issues that I am aware of,and in an almost pristine condition. 1/3rd of those cases split apart 1/4" above the rim. Hornady reps maintain that I loaded the cases past maximum charges. I cut a case in half,length wise. A very thin wall as opposed to Privi cases which is pretty close to the original ammo. It is not a headspace issue. The cases are separating from the combined fireforming, resizing,and the chamber space. Remember my specific question about the case splitting 1/4"above the rim? That is a specific area where the .303 case splits more often then not. Alot of the splitting is the thinwalled brass but,it also has to due with the chamber area.
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Gerrit
Newbie Joined: April 07 2019 Location: South Africa Status: Offline Points: 14 |
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I visited my gunsmith today for some advice. He does have a few old #0 to #2 heads in his shop, but no #3. I assume that more Lee Enfield .303s needed the longer #3 head to compensate for the modern cases. On close inspection of my head, it does look like about a 1.6 mm washer is fitted to the face of the main heae unit. My #2 head measure 16.16 mm (0.63622 inch) but is also not constant when measured at different places around the circumference. I would then need a #3 head of 16.3 mm to fix my problem.
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Zed
Special Member Donating Member Joined: May 01 2012 Location: France Status: Offline Points: 5585 |
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I would suggest asking him if you could measure the #2 bolt heads that he has in stock. Due to the variation in actual size; you may get lucky and find a longer #2 head. The bolt head should be one piece; there should not be anything added on, such as a washer. However there can be a mark appear on the front face caused by the primer if you get a gas leak around edge when firing.
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It's nice to be important, but it's more important to be nice!
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Shamu
Admin Group Logo Designer / Donating Member Joined: April 25 2007 Location: MD, USA. Status: Offline Points: 17603 |
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There was an (unofficial & IMO dodgy) "fix" where shim material was braise or silver soldered to the bolt head to "make it longer". I wouldn't trust it frankly.
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Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)
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Goosic
Senior Member Joined: September 12 2017 Location: Phoenix Arizona Status: Offline Points: 8792 |
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These are ones I have. The top one that has an actual L stamped on it was refaced by myself to fit my No4 7.62x51. Notice the difference between my #2 and my shortest #3. A mere .002" in difference. I have a #2 currently in a rifle that is .636,which is bigger then two of my #3's. Do as Zed suggests and have your gunsmith measure all of his #2 boltheads. Even if he finds one .001 longer then the one you have is an improvment.
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FlyPiper907
Senior Member Joined: January 31 2021 Location: Alaska Status: Offline Points: 188 |
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Howdy folks, late to the party here. So, from what I’m gathering, any 0, 1, 2, or 3 bolt heads may not reflect the same value among the same size bolt heads? I’ve just acquired a Jungle Carbine with a #2 head - still a little long in the headspace department with the current head on it. Worth maybe trying another #2 bolt head?
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britrifles
Senior Member Joined: February 03 2018 Location: Atlanta, GA Status: Offline Points: 6539 |
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Measure the length of the bolt head you have and see where that length falls into the table at the top of this post. From that you can see if your #2 bolt head is on the short or long side of that range. If it’s already on the long side, better look for a #3 bolt head.
Does the bolt close on a field gage?
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FlyPiper907
Senior Member Joined: January 31 2021 Location: Alaska Status: Offline Points: 188 |
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Britrifles,
It doesn’t close on a field gauge but it’s on the long side for sure. The bolt handle stops about 2/3 of the way closed. Certainly safe to fire but I’d like it a little on the shorter side. I’ll get a pair of calipers and have a look.
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MJ11
Senior Member Joined: September 18 2008 Location: Oregon Status: Offline Points: 1882 |
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Another good read on the never ending story. The update is every bit as interesting as the original. Some years ago I was at a match and met a retired gent who had a #3 with a .003" bit of stock added to the bolt face. He had had no problems with it and claimed several hundred rounds of reloaded munitions through it at the time. Point is I had never seen that approach to the problem and had just went about collecting as many bolt heads as possible. The conversation had come up because I had a 7.62X51 LC match case separate 3/8th inch above the rim taking me out of the contest. The Gentleman was all about wanting to fix my rifles bolt head but I let it pass because I knew it was my fault trusting a batch of even LC Match 69 case after seven reloads. I then knew why there was a line of vertical stations on those cases. Live and learn. Also I never went to another event without a ruptured case remover.
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The Spartans do not ask how many the enemies are but where they are
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britrifles
Senior Member Joined: February 03 2018 Location: Atlanta, GA Status: Offline Points: 6539 |
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I also like to have headspace right at minimum if possible. It extends brass life. 40 to 50 reloads before case head cracking...relatively mild loads help too.
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Goosic
Senior Member Joined: September 12 2017 Location: Phoenix Arizona Status: Offline Points: 8792 |
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My headspacing is as such that with a No-Go gauge, the bolt handle has only traveled 65% before lockup. The fired case in the case gauge as compared to an unfired case look identical.
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Twodogs
Groupie Joined: December 05 2018 Location: England Status: Offline Points: 96 |
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Or even better look for a longer bolt head which may well be marked with a 3 or a 2 o a 1. The need for a longer bolt head will also tell you the rifle is wearing out. Number/size relationship aside these rifles never left factory/ base repair with a no3 bolt head.
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FlyPiper907
Senior Member Joined: January 31 2021 Location: Alaska Status: Offline Points: 188 |
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That would make sense. You should’ve seen the copper in that barrel. Very clean now, stripped her all the way down. My guess is the gun hadn’t been apart since it left the factory. Wood was in great shape, can’t wait to take it to the range
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FlyPiper907
Senior Member Joined: January 31 2021 Location: Alaska Status: Offline Points: 188 |
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Would changing the bolt to a new bolt help with headspace as well?
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Goosic
Senior Member Joined: September 12 2017 Location: Phoenix Arizona Status: Offline Points: 8792 |
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Your field gauge is a SAAMI spec'd gauge with a .070" rim thickness. If your bolt is stopping 2/3rds of the way down leave the rifle alone. The,"Official" headspace gauge has a rim thickness of .074" and with that in mind, your rifle is beyond good to go, just from what you have said in regards to where the bolt handle is stopping. Using the .074" headspace gauge. The headspacing was found to be acceptable with the bolt at 80 - 90% travel before stopping. You are overthinking this.
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