Supressing a Glock pistol vs a HK vs a Sig

[larryccf]

this only applies to the USP Series HK pistols and pre 2003 SIG pistols

For years i'd read on the web, the web wisdom that the Glock pistol was quieter when suppressed with the same suppressor than either the HK or the SIG. And foolishly, i accepted that "web wisdom". It was not until after we started the CCF RaceFrame project of manufacturing metal replacement frames for the Glocks that I learned different. That "web wisdom" was based on false knowledge that the Glock's action stayed locked longer, thus preventing noise escaping out the ejection port. It was during the RaceFrame development , and we were exploring the cause of the Glock "kabooms" that everybody attributes to the unsupported case. Well, i don't doubt the unsupported case exacerbates the kaboom issue, but it isn't the cause of it.

Take a glock, cleared of all ammo, and pull the slide back a hair - and i mean a thin hair. The barrel starts to unlock from battery or the slide and dropping down within 10-15 thou of travel rearward. Surprisingly, if you pull the trigger, it will release the striker for a considerable amount of travel. Frank Di Nuzzo, who was chief armourer & firearms instructor at Glock USA for 13 years, told me the standard frame glocks (17/22/24/31/34/35 & 37 ) would fire out of battery up to 55 thou of travel.

To me that's a big safety issue. Do the same with the HK USP series pistols or the SIGs, and the barrel doesn't start to unlock from battery and dropping down for about 100-110 thou of travel - the HK USP will still fire for about 50-55 thou of travel, but keep in mind the barrel is still fully locked in battery. Then for the last half of it's 100-110 thou of travel, the HK will not release the hammer, even though the barrel is still in battery. That's a big safety plus to me. The SIGs were similar in amount of travel before they started unlocking and how far they'd travel and still be able to fire.

Think about the glock, if there's powder fowling in the chamber keeping the round & barrel from going forward into full battery, but still being able to fire - now there's even more of the case exposed unsupported.

But the HKs and the SIGs staying locked longer made for a quieter sampling on the suppressor sound level.

FWIW

 

[AGG]

Awesome information.

Tony

 

[Guyanaman1963]

Educating post, Thank you very much.
How does one do such precision measurements?
Just curious.
M.

 

[Crashmc]

Good information , great post !

 

[larryccf]

another pc of info that may serve, over the years on That Site Whose Name Shall Remain Nameless (from here on referred to as TSWNSRN) folks would post about about having issues with their compact pistols (whatever brand but Glock compacts seem to be the most populous). And folks responding something along the lines of "it's well known the compacts and subcompacts are poor choices for supressing. Well when it was glocks, i assumed folks weren't aware of how the aftermarket suppliers were really delivering way out of spec components to the glock community and they get away with as the glocks (up thru gen 3) the frames had so much flex, what we referred to as the "squish" factor at CCF RaceFrames - that flex makes for a forgiving frame, forgiving in terms of being tolerant of out of spec components. Being tolerant does not mean it's a good idea to run an out of spec component but to the average user their glock would appear to run fine.

Whenever i saw a post like that i assumed they were running an aftermarket threaded barrel and just were not aware (this was before glock started offering threaded barrels) - so you're aware, i've seen countless aftermarket glock (not glock OEM) barrels with lugs offset forward from where they should be, some more than .125" - you read that correct, more than 1/8th"- i have here right now ,from what's considered the premiere glock bbl maker, with one bbl's lug measuring .131" forward of where it should be and another .134" forward of where they should be. But i knew our IMPULS IIA had never had an issue on a compact, never tried it on a sub-compact glock.

Then a few years ago, i had sent a DEA supervisor a compact IMPULS IIA for evaluation at his request (i had removed 3 baffles and added a 1/4" thick polymer wipe). They were , at the time, supplying various drug task force teams in northern FL and GA and they had supplied them with G27s and wanted a compact suppressor not so much for silencing but for flash signature containment.
Well 3 months later i get a call from that DEA supervisor and he sounded like (well almost) like a 14 yr old who discovered sex, telling me my can was the only one that had not experienced a stoppage on the range among 18 cans, and they'd run mine out to 250 rounds with no stoppages. He said some cans they had to cycle manually almost every shot.

I was curious so i asked him did he remember the barrel maker on the pistol running my can - his response was Glock, they were all glock barrels. That was when glock had just intro'd the threaded barrels, about 2012. But his response told me something else, the glock barrels would be all pretty standard and within decent manufacturing tolerances, so now that meant that the other can manufacturers had issues with their recoil booster system. I knew a lot of the other can manufacturers had copied the B&T recoil booster piston, they had omitted or not seen one element in the B&T piston design. Sorry but i have to keep that proprietary - even though i had terminated our agreement with B&T (no, i'm, not a fan of B&T) i had to give the engineer that designed their recoil booster piston credit.

FWIW

 

[larryccf]

Educating post, Thank you very much.
How does one do such precision measurements?
Just curious.
M.

sorry, just noticed your question - it's fairly easy to measure how far back the pistol will still fire with the barrel dropping out of battery - go by Track Auto and pickup one of those 1/4" wide feeler guages, and after racking the slide to cock the striker, see how many of the guages you can drop into the dovetail where the barrel's chamber hood goes into, and still fire the striker.

Frank Di Nuzzo, who was chief armour for Glock USA for 13 years, told me the standard frame glocks (17/22/24/31/34/35/37 would fire up to 55 thou of slide travel, but remember the barrel is unlocking almost instantly. For those non-machinists, .062 or 62 thou = 1/16"

 

[D9M9TR9S]

A few members here may be highly interested in a shortened can for the USP. Especially since KAC doesn’t make theirs anymore. Just fyi

 

[larryccf]

I CAN MAKE some, the issue is the wipes - ATF ruled rubber wipes are regulated 1.5 months after issuing a ruling letter re copper scouring pad media, declaring the copper scouring pad media, unlike rubber wipes, are regulated. Then in a response to my ruling letter requestion a delination on wipes, they ruled the wipes were regulated. They killed a major sale to the DEA -
Users would have to be willing to making their own wipes, one at a time. On the upside we were able to demo the wipes good for just south of 90 rounds using some silicone grease on the back side of the wipe, but i'm not sure users would want to make them one at a time. I designed a tool that users could use in the drill press (just using the drill press as a press) to punch out their own wipes but never fabricated any.

Surprisingly, the shortened can with one wipe was actual quieter than a full size can, but you had a long (maybe 1.5 - 2 seconds) loud hiss as the expansion gas .

ATF actually told DEA that i could transfer a large quantity, say 300 wipes to them on the appropriate form., then as they replaced them one at a time, they could write in destruction notices to ATF NFA that they had destroyed another wipe. DEA supervisor asked "why would you want to make us write 300 letters, and you have to read them and then have to make 300 adjustments to the registry?"

 

[larryccf]

this might give folks some idea of how out of spec the aftermarket barrels for the glocks are - the glock polymer frames (up thru gen 3, i can't speak for gen 4 and later) but up thru gen 3 the frames have so much flex, they'll tolerate out of spec barrels and still appear to run fine. Because of that "tolerance" of out of spec components, the aftermarket barrel makers are running their barrels at a faster cycle time and dropping quality.

Note in figure 3, the red arrows highlighting the contact strike marks - that is the front wall of the well where the glock's barrel lug drops down into when the weapon cycles. The lug's angle is similiar to the angle of that wall, and when the weapon cycles, the lug as it travels downward travels parallel to that wall. We cut windows in a number of glock frames and in each we measured a .094" gap between the front of the barrel lug and that wall. The barrel that was being run in the frame pictured in fig 3 was an aftermarket barrel from what is considered the premium glock barrel maker. That barrel's lug mike'd at .129" forward of where it should have been - for the un-initiated, .125" = 1/8". Note in fig 4, the front wall of that well shows no contact strike marks. That frame had been run in an evaluation with a stock Glock 22 upper - no contact period.

In building a FAQ page for our web, i went down and grabbed an aftermarket barrel from a box of aftermarket G22 barrels and brought it up to compare to an OEM Glock G22 bbl. I hadn't looked for the worst barrel, just grabbed one at random. In fig 1, both barrels have their chamber hoods butted up a metal block in the right side of the picture, to give them a common datum reference point. Note the front edge of the bright stainless barrel's lug of the aftermarket barrel, and extend that edge down onto the glock barrel below. It extends down nearly to the front edge of the step on the glock barrel. When i was thru building that webpage, i was curious so i took all 15 of the aftermarket bbls on hand and brought them up to mike. None of the 15 were alike, the range in lug height was .032", the shortest lug being .010" shorter than an OEM G22 barrel, and the tallest was .022" taller, but no consistency in height. The same held true for the lug's front to rear length.

When i state the glock aftermarket barrels are for the most part all over the map in terms of tolerances, they are. We decided we needed to offer our customers at least one option in the way of a quality barrel. I remember calling the gunsmith that builds the Glock shooting team's pistols to ask him what barrels he runs, hoping he had somebody i hadn't heard of - hopefully we could get barrels "private labeled" and not have to produce them ourselves. His response was the very barrel maker that is considered the "premium" barrel maker that is pictured in all the pix. - i stated how, and told him what i'd found on the last shipment of barrels. He said he had a relationship with them, and would order 10 barrels, and when he received them, he'd mike them picking the 3 that at least had enough "meat" where the lug was so that he could machine them down to what they should be, and send the other 7 back for credit. Wrap your brain around that.

Surprising, i happened to order a couple of aftermarket HK barrels for the USP 45 - both those barrels were awfully close to spec - but they have to be as the HK and the SIGs are not tolerant of out of spec components. It's pretty much a case of the aftermarket makers knowing they can get away with shipping out of spec bbls with the glocks and save cost on production costs.

FWIW

 

[AGG]

Excellent tutorial.

Tony