I just measured the bore of my T8 30cal mod and it's .344.
moderator bore (hole) size
- Thread starter Miki
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My numbers came from Bill rather than dieect
i converted his measurements in inches to mm so there may be some margin of error
would like Ike to see more of them to measure an absolute bore
i converted his measurements in inches to mm so there may be some margin of error
would like Ike to see more of them to measure an absolute bore
sparko
Well-Known Member
Almost sure this Is a DM80 (Dave Mercer) moderator.
Ace - cheers Sparko, that clears up a puzzle. The guy who sold it to me said it was a Wildcat but I asked UCS and they said "nope".
Came across an interesting article on Jackson rifles site http://jacksonrifles.com/zz-silencers/techinfo.htm which suggests a '1mm larger than cal' bore as a minimum and that the addition of baffles offers more noise reduction than a smaller hole.
1dB is around 20% so it does help though less than additional baffles - which is what makes the modular approach interesting/attractive.....
1dB is around 20% so it does help though less than additional baffles - which is what makes the modular approach interesting/attractive.....
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That is DPT's mantra, 1.2mm larger than the cal. The .284Win is 7.22mm so you should have 0.55mm radial which is plenty. The next size down (25cal - 6.5mm) has a 7.7mm bore which only offers a 0.25mm radial clearance - a bit tight but it should fit (not that I am reccommending it
) it sounds like you have a good fit with the 7mm.Have you got the overbarrel (reflex) type with 4 fwd baffles ?
My experience with the DPT has demonstrated that the hole size does matter. I swapped the front baffle stack as supplied on my 25.06 (25cal 6.5mm, 7.8mm bore) for a 6mm stack, which has a 7.5mm bore. On both 5 element front stacks I added a stainless 'blast baffle' one size up. On the original 25cal stack it was a 30cal baffle, on the 6mm stack it's a 6.5mm baffle. Both screw onto the reflex (over barrel) carrier which allowed me to make a direct comparison.
The 25cal barks like an angy Rottwieler through a megaphone whilst the 6mm woofs like an old Labrador. The 'crack' is still heard but there is a noticable difference between the two bore sizes. Tighter to the projectile size is advantageous. As is adding more baffles. With the 6.5stack (4 element) behind the 5 element 6mm stack the moderator becomes 290mm long.... 190mm forward, weighs 0.425kg and the bangs characteristics change.
The 'crack' becomes louder and the smack of the round hitting the target gets louder, the "woof" still sounds the same to be honest but I guess overall it's quieter, moderated more at specific frequencies, as these other 'events' have become more prominent.
Sorry it's not that scientific but my conclusion is that the size of your hole does matter and the tighter the better
View attachment 79414View attachment 79415
The 25cal barks like an angy Rottwieler through a megaphone whilst the 6mm woofs like an old Labrador. The 'crack' is still heard but there is a noticable difference between the two bore sizes. Tighter to the projectile size is advantageous. As is adding more baffles. With the 6.5stack (4 element) behind the 5 element 6mm stack the moderator becomes 290mm long.... 190mm forward, weighs 0.425kg and the bangs characteristics change.
The 'crack' becomes louder and the smack of the round hitting the target gets louder, the "woof" still sounds the same to be honest but I guess overall it's quieter, moderated more at specific frequencies, as these other 'events' have become more prominent.
Sorry it's not that scientific but my conclusion is that the size of your hole does matter and the tighter the better
View attachment 79414View attachment 79415
The overbarrel type would not fit over an F-class barrel! This is a muzzle mounted type with 7 baffles.
I've got an overbarrel type for the .223's, with 10 baffles.
musketsmoke
Well-Known Member
moderators are a funny thing if the gap is to big it will not work properly
if the air gap is to short or to long
if its to small it may strike the internal bits
as well as the shape and gaps between the internal baffles
best to buy one from a manufacture with a name they have done all the research
usually between 20 to 50 thou space around the projectile
depending on the caliber and what ammo are used
projectile shape and speed through it also a factor
this is potentially a mathematical night mare if you dont get it right
so usually the sold ones are a compromise for the general shooter
if the air gap is to short or to long
if its to small it may strike the internal bits
as well as the shape and gaps between the internal baffles
best to buy one from a manufacture with a name they have done all the research
usually between 20 to 50 thou space around the projectile
depending on the caliber and what ammo are used
projectile shape and speed through it also a factor
this is potentially a mathematical night mare if you dont get it right
so usually the sold ones are a compromise for the general shooter
On a 24" Tikka super Varmint T3X and 24" T3 Varmint, apart from the supersonic crack, the loadest noise seems, from behind the stock, to be the bullet strike.
I think this is the key, more baffles (which is obvious really) and a bore diameter close to the bullets size, it makes you wonder why the "standard DPT" is only 5 baffles ? and their std bores so cavernous.
It's an expensive habit too, as an overbarrel/reflex modetaor + the additional 5 baffles is £230 + £145 (list)
Priced to compete with other stuff on the market, I suppose.
Once you have the DPT base, you can buy extra baffles and end caps of any size you want with nothing going on the FAC.
The over-barrel DPT can take up to 10 baffles, while the muzzle-end type can take 7 baffles.
A bit like the Model T Ford, they reckoned they made more from spares than when the car was sold new.
20-50 thou is a big range.
20 thou clearance (diameter) is where I want my mods, 10 thou radial clearance is plenty for a well fitted moderator
50 thou is far too big IMO
the majority of mods have diameters in excess of 60thou or 1.5mm clearance.
very few of the manufacturers are willing to produce moderators for maximum suppression
too many variables with the fitment
That said regardless of the overbore, if you have a non concentric thread or shoot the rifle with the moderator loose and it clips or damages/destroys the moderator as a result of that you are unlikely to see a warranty claim.
So the overbore tolerance is a simple one
Cost.
7mm bore can fit anything from 6.5mm down to .17cal and reduces the cost of tooling for calibre specific baffles
I had a mod with an 11mm bore come in the other day!
even shooting 9.3mm it is far too big
I have just tried the Wilcat Evolution (green diffuser) moderator on my Steyr Prohunters (243 and 260). It looked a bit tight on the 260 but worked brilliantly, which is a testament to Steyr`s thread cutting and Wildcat`s engineering of their bridge threads.
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