AR-10 in 6.5 Creedmore ... barrel length?

So long as the suppressor can be removed from the barrel and was not built onto the barrel as a permanent part of the barrel - it doesn't count towards the mandatory barrel length.

I believe you may lose a bit of velocity with a suppressor as is generally the case with a muzzle brake which will decrease cyclic rate in an AR. As you might imagine adding an additional 9” to the overall length must be factored in when considering purpose. That or I’ve got it all wrong.

If you’re looking for specific pages to see suppressors, Thunder Beast Arms https://thunderbeastarms.com or Silencerco https://silencerco.com should give you a better handle on them.

Adding an 8” suppressor is not the same as adding 8” of barrel length. However, it DOES represent more time with pressure behind the bullet, so most quality suppressors do add velocity over the same barrel without the suppressor.

Suppressors should not touch the bullet in any way, such the smallest ID of the can is larger than the groove/bullet diameter. Baffle strikes with poorly threaded barrels are common, as the can isn’t coaxial to the bore, either linearly or axially.

Muzzle brakes increase sound delivered to the shooter. They also do nothing to reduce sound signature anywhere else in the field. The opposite is true for the suppressor.

Muzzle brakes are used to reduce recoil effects, whether that is the impact to the shooter, or muzzle hop (for watching your own shots). They redirect gas away from the tail of the bullet, back at the shooter, effectively pushing the rifle forward and down in the process. They also increase the relative exposure “face” of the depressurization, such the velocity upon introduction into free space is reduced - which reduces recoil as well.

A suppressor isn’t typically as effective as a muzzle brake at reducing recoil, but they do. They also add weight which reduces recoil even further than the gas depressurization.

I like shooting suppressors because of the sound reduction - they are universal hearing protection. The increase in total firearm length is a consideration, but should not be the ONLY consideration.

Yes, suppressors are silencers, and NFA items.

Federal as well as state. NFA is National Firearms Act, so the restrictions placed on them are federal. However, states can also prohibit possession of NFA items within their borders.

Iowa became the 42nd State to again allow them in 2016. Not holding my breath for Illinoisans to enjoy the same freedoms.

The quick explanation is the NFA made them a restricted item way back when. If permitted by your State (or if you set up a trust in a legal State) you purchase a suppressor, apply for it with a check-$200 iirc, and the feds may or may not grant permission for you to pick it up. That’s the gist of it anyway.

Denny Gibson said:

So are they ever, actually legal?

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Yes. Pay your $200 tax, pass the application background check, and live in a city/county in a state which isn’t ran by Freedom hating liberals and you can be legal in the US to own, make, buy, and use a suppressors/silencer. All of mine are 100% legal. Part of the application process even includes notifying local law enforcement of my application to possess the NFA item.

Want a “sawed off shotgun?” Read the above. Want a short barreled rifle? Read the above. Want a suppressor? Read the above.

Denny Gibson said:

I guess what I’m suggesting is that adding a suppressore leaves you with the same length barrel you started with. If it’s too short without a suppressor it’s too short with one, too. That’s the facts as they appear to me (45 years as a mechanical engineer teaches one to think through statements like these rather take them at face value). If you disagree please explain why.

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Adding a suppressor leaves you with the same length barrel, but a longer overall package. For me, ideal rifle barrel length depends not only on my ballistic requirements, but also whether I'll be using a suppressor or not. For most rifles If I am using a suppressor I like barrels in the 16" - 20" range for full power rifle rounds, I'm giving up some velocity as compared to longer barrels, but it is worth it for a more compact overall package. If I'm not using a can, I prefer barrels 20" - 24" depending on caliber and application, for the little bit extra velocity and more moderate muzzle blast. A rifle can be shorter than preferred without a suppressor, while the same rifle might be perfect with a can added (dependent on the users wants of course).

Case in point :
I had this .30-06 chopped from 22" to 18.5" and threaded. With my full power handloads, unsuppressed it bucks, and is very, very loud, to the point of being unpleasant.



Suppressed, on the other hand, it is below the hearing safe threshold at my ear, soft shooting and has an overall length similar to a rifle with a 25" barrel.


One of these configurations is too short for me, the other one is just right.


To answer your original question, I think I'd go 18" to 20" if you're going to suppress and want to keep the overall length down. If you're not going to suppress I'd probably go 20" to 22".

I had my 6.5 Creed hunting rifle cut to 20" from 22" and still get over 2,700 fps with 140s. An 18" can still do quite well depending on how far you're shooting, but bare muzzled, it will be loud.

Denny Gibson said:

Well ... I finished building the rifle AR-10 in 6.5 Creedmore) with the 18” barrel and a Little Bastard muzzle break. Early load development shows an unexpected result (at least to me) result. Surveying the landscape I shot 5-shot groups with H4350 and a 140 grain Hornady Match HPBT with charge weights from 37 to 41 grains in 1 grain increments. In other rifles (and in my expereience) this test usually shows that, as velocity increases so does group size. In this case the most promising group occurred with 38 grains. Obviously I’ll do more exploration but I was surprised that the smallest grouping happened about half way between the minimum and maximum loads in the Hornady manual.

The questioon is: what are y’all’s experience with load develop (faster, up to a point, is better)? Is barrel length part of the story?

Thanks!

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If you move thru enough of the velocity spectrum, youll usually see groups tighten then open, as you go in and out of nodes.
My reading suggest that there are usually known velocity nodes for each cartridge thats commonly used by accuracy guys, but i dont know them.
My best 6.5CM loads have been to be right around 2800fps with a 140, much higher and pressure signs show up, lower and you need to be down around 2650ish before groups tighten up again. This is only with 2 rifles, both with 22" barrels.

Personally I usually go pretty high with bolt guns to see if theres accuracy at the top of the pressure/velocity range, if not I work back till i get the accuracy i want. With a gas gun, and others will be more knowledgeable than I am, im not sure pushing hard enough to find a node at the top end is an options.

Denny Gibson said:

I wish I could buy and install a suppressor ... but, like Skyler says ... probably not in Illinois.

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Start lobbying with grassroots groups! Or plan your escape from IL.

Silencers certainly don't do what you see in the movies, but they're definitely worthwhile. Supersonic rifle rounds can be suppressed down to the 132-138 dB range, just this side of hearing safe. Subsonic centerfire rounds in the 118-130 range. Subsonic rimfire can be below 110 dB with an integral can, or the mid one-teens with a screw on. That's quieter than most people clap their hands. I have one .22 LR integral design that I haven't metered yet, but it's quieter than a Red Ryder BB gun.



The purpose and benefits have been pretty well covered, but I can show you. These are all short clips of the cans I produce:

Most applicable to you would be my Gyrex 6.5. I demonstrated with my wife's Savage Axis .243 with a 20" barrel



The Valkyrie 30 on an 18.5" .308



Valkyrie 224 on a 16" 5.56mm AR



Phoenix IX on a DB9FS 9mm



Ocelot on a Stoeger Luger .22 with a custom adapter



And a Suomi Subgun with my Vorticis carbine can

https://www.youtube.com/watch?v=S4Ti7S2t5Ns

with the 6.5CM suggested nodes are mostly what i ran across when looking for 6.5CM load data. Its dependent on rifle, barrel, and load as well.
Some of the other cartridges i looked at had multiple post with guys finding fairly consistent nodes over a few different rifle, again i havent looked hard enough to be able to give you a better answer tho, sorry.

For my self, Im using Superformance, which isnt one of the more common powders. I went from 43-47.5Gr (47.5 was pretty hot), in half grain increments. Accuracy was junkish on the low end and tightened up around 46.5-47 (both produced similar accuracy, round 1") 47.5 opened up.
This happened with both my Howa, and my Savage, tho i started my savage at 45 and went to 47.
velocity for both was single pretty much right at 2800.

Most of the folks I've talked to at the long range and at matches who are running H4350 in 6.5 CMs are running between 42gr and 43gr with 140gr weight class bullets. I settled on 42.5gr under 140gr Nos CCs as the load for my RPR early on, it's over book max, but the 2,740 fps I get certainly isn't unusually fast for a 24in barrel.

You might not have the headroom in your AR that a stout bolt gun would, but personally I'd probably work up a bit further as long as you're not seeing pressure signs. I like to use 1%-ish intervals for my OCW load workups, so for the 6.5 I'd use 0.5gr.

Another option is Reloder 16, which is what I use now in my hunting rifles, shoots well and gives better velocity than H4350.