New! The S.I.A. "Trecenti" 300 BLK integral suppressor

[Richard/SIA]

Six baffles equally spaced.
Spacers are integral to the baffle.
I have found that putting more baffles too close together is less effective.
So fewer actually work better as the gas gets a chance to expand between baffles.

Nothing spectacular.
Keeping cost down and serviceability up.
Pic from my site.

[rpk47]

I checked out your site, by chance is this 300blk set up similar to your De Lisle set up (awesome by the way) with the barrel being ported in the grooves?

[Richard/SIA]

Not quite, the lands and grooves for .30 are very close together to keep the ports between the lands.
I also felt that there really is not enough barrel length after the gas port without losing the residual pressure needed to operate the action.
So I port into a short extension added at the end of the barrel.
The extension can be reamed after porting so no need to use the slow EDM process.
Could probably use a 10" barrel but I want the short pistol gas tube for overall length.
The 8.2" barrels with pistol length gas tube are readily available.
If I was sure it would operate properly and be reasonably accurate I would use an even shorter barrel.
From what I can find 8.2" is pretty well the minimum practical barrel length.

[A-Game]

I'm in NW phoenix valley. I'm always game for a demo to compare to my 16" AAC MPW

[USBP379]

I think something like this on an HK53 clone would be spectacular. Think of an MP5SD but in 300BLK rather than 9mm!

[Richard/SIA]

I'm about to go out and try a slightly lightened bolt.
The "Best" load I have on hand works great except that it does not lock the bolt back on the last round.
No big deal for some folk, unacceptable to others.
I have another load that does lock the bolt but it's transonic and you can clearly hear the difference.
I also have some Remington 220 gr. coming next week so that I can try it with a factory subsonic loading.

As to other guns, ah well, I probably should not talk about that yet.
Lets just say there is another possible suppressed 300 BLK project on the "To do" list for next year.

[Richard/SIA]

Trying to get the Trecenti to work better with less expensive 190 gr. bullets while remaining subsonic.

Spent the morning doing some experiments.
Tried out a 1.5 oz lighter bolt with no other changes.
Yes, it does make a difference.
The issue has been last round bolt lock.
The bolt already locked back on a load that I was not happy with as it seems to be transonic.
The sweet load is quieter than 9mm and functioned just fine except that it rarely locked the bolt despite opening the adjustable gas port.
With the lighter bolt is does lock back reliably with the gas port only partially open.
No other changes were made.
Switched back to the standard bolt and lock back was lost.

A lighter bolt can clearly make a difference but I hesitate to use it with the slightly higher load as I am certain I would have to close the gas port way down.
Ideally the gas port could be adjusted and then left alone for varied loads.

Next round of experiment is to try out the Rem. 220 gr subsonic that is to arrive by Wednesday.
Pretty certain that will work fine with the standard bolt and with the light bolt I will have to close the gas port down.

One interesting result from this morning is the conclusion that 190 gr. 300 BLK subs are quieter the to the ear than 147 gr. 9mm out of essentially identical suppressors.
But the blow-back 9mm has less action noise than the gas operated 300 BLK.
I also note that as the shooter rounds which do not lock the bolt back seem to be quieter than those that do.
Witnesses did not seem to notice a difference.

I may make the light bolts an option for those who want to shoot the lighter bullet (less expensive) subsonic rounds.