M781 TPT (Inert) Round Components

[ChevTec]

Props on keeping up with this thread and all the info. I really need to get some of those green aluminum cases as they look so cool! Just had to justify when I'm sitting on boxes of m212 nylon cases

[Rekraps]

5 hours ago, ChevTec said:

Props on keeping up with this thread and all the info. I really need to get some of those green aluminum cases as they look so cool! Just had to justify when I'm sitting on boxes of m212 nylon cases

No kidding. I have about 25 of the aluminum (no finish shells) and 25 of the green aluminum shells in addition to the 300 complete nylon shell blue rounds and lots of pushers and wind screens. 

The problem with the aluminum shells is that after at most two shots, they have to bee resized as the top 1/3 swells. Joe Jones is working on a die for me. Now I will say, the rounds in the aluminum shells SEEM to travel much further and faster. No way to prove it, but shooting them alongside the nylon shell rounds that is my impression. Also, loading the impulse round (.38 Blank) into the aluminum shell takes a nylon hammer or a vise to press in, whilst with the nylon shells it does not. Shooting the aluminum shells with sponge tips and .38 special half/loads does not swell the shell. And man do those sponge tips move.

[Rekraps]

So I looked at the interior of the nylon and aluminum shells to see if there was a difference, and yes there is. The small opening at the top of the impulse chamber (where the blanks fit) is much smaller on the aluminum than nylon shell. So, this means that the pressure in the aluminum impulse chamber gets much higher before releasing into the much larger main expansion chamber. This is probably why I "feel" that the aluminum shells shoot faster. 

[ChevTec]

On 4/22/2024 at 9:21 AM, Rekraps said:

So I looked at the interior of the nylon and aluminum shells to see if there was a difference, and yes there is. The small opening at the top of the impulse chamber (where the blanks fit) is much smaller on the aluminum than nylon shell. So, this means that the pressure in the aluminum impulse chamber gets much higher before releasing into the much larger main expansion chamber. This is probably why I "feel" that the aluminum shells shoot faster. 

Yes I definitely tell everyone to drill out the aluminum shells vent holes. Some people have had them blow out as well. I tried it once in my lightweight break action LMT and thought I dislocated my shoulder haha. I only use them with crimped low power blanks for less lethal projectiles unless they are drilled out to m212 spec

[Rekraps]

On 4/24/2024 at 7:47 PM, ChevTec said:

Yes I definitely tell everyone to drill out the aluminum shells vent holes. Some people have had them blow out as well. I tried it once in my lightweight break action LMT and thought I dislocated my shoulder haha. I only use them with crimped low power blanks for less lethal projectiles unless they are drilled out to m212 spec

Thanks for the tip. They felt "overpowered" to me. I don't want to take chances, plus the damn round flies totally out of sight! Not good for backyard shooting.

[ChevTec]

On 4/27/2024 at 4:24 PM, Rekraps said:

Thanks for the tip. They felt "overpowered" to me. I don't want to take chances, plus the damn round flies totally out of sight! Not good for backyard shooting.

Yeah you'll want to drill them out to at least 1/4 inch. Pretty simple to do with a hand drill. You can go slightly larger but it's not needed. I have seen the aluminum cases damaged from shooting them with full power, burst disk blanks. 

[Rekraps]

44 minutes ago, ChevTec said:

Yeah you'll want to drill them out to at least 1/4 inch. Pretty simple to do with a hand drill. You can go slightly larger but it's not needed. I have seen the aluminum cases damaged from shooting them with full power, burst disk blanks. 

So this may explain why my aluminum shell with full power blanks have the top 1/3 bowed out.... making them hard to extract. I'll use 1/2 power blanks from now on, instead of drilling.

[Rekraps]

On 4/29/2024 at 7:11 AM, Rekraps said:

So this may explain why my aluminum shell with full power blanks have the top 1/3 bowed out.... making them hard to extract. I'll use 1/2 power blanks from now on, instead of drilling.

A friendly reminder to those of you who reload your own M781 rounds.... full power .38 shorts send that thing down range quickly, be careful. I had one hit a tree and the pusher landed almost 50 feet away from the strike area. ONLY use 1/2 power .38 special loads for the non-lethal sponge rounds.