Hollow Det Pin Conversion

Has anyone experienced a decrease in blowback force when switching to a hollow det pin design?

Cheers,

Victor

Dont have a hollow det pin so cant comment on that, however as the blowback power is all down to the round i would not think the det pin had any effect. Does the piston in the round also have a hole in it or do you have a worn seal on the piston as those would be the likely cause of low blowback power i would think.

claymore wrote:

Dont have a hollow det pin so cant comment on that, however as the blowback power is all down to the round i would not think the det pin had any effect. Does the piston in the round also have a hole in it or do you have a worn seal on the piston as those would be the likely cause of low blowback power i would think.

Hi Claymore, it's more that I'm trying to consider all variables. I'm still marching (slowly) toward a barrel venting conversion on my Hudson M1A1, and have already increased the weight of the bolt considerably. To get it to flash out the barrel, I assume I'll need hollow pistons as well as a hollow det pin. Just trying to wrap my head around it, and make sure I can still get it to cycle before moving forward with the invasive surgery

A hollow det pin by itself won't get you any muzzle effects with a long barrel like on the M1A1.  You would most likely need to use a hollow inner piston in your cartridges that uses it's own cap, as well as the addition of some Al or prop powder most likely.

Then, as you've suggested, you will have a difficult time operating a heavy bolt with the cap charge(s) energy being split. Main spring experimentation will likely be in your future!

With the whole gas bypass setup of the M1A1, I am curious how you'll get along.  Have you managed to drill the carbide insert in front of the det pin?

Please keep us posted.

ljerr2 wrote:

With the whole gas bypass setup of the M1A1, I am curious how you'll get along.  Have you managed to drill the carbide insert in front of the det pin?

Please keep us posted.

Drilling is still on the table, but I actually think it will be easier to mill out a channel between the chamber and the rest of the barrel. Basically a long slot that I'll machine a mating insert for that will be bored out to line up with the remaining barrel. It'll require a new det pin, and hollow plungers... Honestly it's going to be so invasive I still might not do it, but I really really really want to.