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  #76  
Old 02-21-2019, 07:58 AM
zukiphile is online now
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Quote:
Originally Posted by octanejunkie View Post
What exactly are we doing here?

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He is making a weight that will attached to the bolt and the leg that hits the back plate of the bolt frame/fork. He ordered a forward assist adapter to check his dimensions, but he is making it from solid steel or brass and cutting a path for the hammer to swing and the firing pin to be removed.

This will add approximately two ounces and will bring the total reciprocating weight up to about seven ounces, the approximate weight of a 10/22 bolt.

The benefits should include gentler recoil/lower bolt velocity with less pronounced slamming against the back plate, and a longer period during which the bolt stays closed after ignition. This may allow it to run better and/or cleaner with a 20 inch barrel or a suppressor, or utilize hi velocity ammunition without port pop.

Last edited by zukiphile; 02-21-2019 at 08:10 AM.
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  #77  
Old 05-07-2019, 09:19 PM
ILhondo
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I'm waiting now on a quote from eMachineShop. The drawing was easy enough after I ordered a CMMG bolt assist piece to check my best guess dimensions. The program won't provide a quote but an earlier design was pre-approved so this version should be also. This will probably be expensive, so, I thought about 3D printing which may be a little less expensive so I'm still investigating this angle.

Another way to add weight as opposed to a slug that mimics the CMMG bolt assist piece would be a bolt handle that reciprocates with the bolt. I've saved some pictures of CMMG upper conversions with a slot in the upper and a bolt handle, both right and left handed versions. It appears that the bolt handle was inserted in the area of the bolt where the cotter pin holds in the firing pin. I'd really like to see a picture of one of those modified bolts. The slot would be fairly easy to do.
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  #78  
Old 05-14-2019, 08:45 AM
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Quote:
Originally Posted by ILhondo View Post
Another way to add weight as opposed to a slug that mimics the CMMG bolt assist piece would be a bolt handle that reciprocates with the bolt. I've saved some pictures of CMMG upper conversions with a slot in the upper and a bolt handle, both right and left handed versions. It appears that the bolt handle was inserted in the area of the bolt where the cotter pin holds in the firing pin. I'd really like to see a picture of one of those modified bolts. The slot would be fairly easy to do.
I saw this today, but don't know if that is the slot you need.

https://www.jsesurplus.com/AR-15SBUB...EXCLUSIVE.aspx
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  #79  
Old 05-14-2019, 09:54 PM
octanejunkie

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That's an expensive upper receiver, but how much weight can a handle add?

Why not fashion a pair of slabs, the same profile as the reciprocating bolt mass, with a hammer channel down the center and weld them to the rod guide?

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  #80  
Old 05-15-2019, 05:35 AM
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Quote:
Originally Posted by octanejunkie View Post
That's an expensive upper receiver, but how much weight can a handle add?

Why not fashion a pair of slabs, the same profile as the reciprocating bolt mass, with a hammer channel down the center and weld them to the rod guide?

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He is working on that, but his other idea is a bolt handle weight.

The problem with an internal weight is the room within the BCG and in the upper half of the BCG is very limited. He has roughed out a weight that really uses all of the available space, but that's real design and machining, so it isn't a cheap solution. My less elaborate idea is a piece of stainless 7/8 inch OD pipe cut in half length-wise, then cut to allow the hammer to drop, and attached to the back of the bolt and guide rod. My idea wouldn't weigh as much.

IlHondo's idea of an external handle/weight gets beyond that space constraint.

Last edited by zukiphile; 05-15-2019 at 09:03 AM.
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