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First Custom Rifle Build | Tips Appreciated

lancetkenyon said:
Your thinking on twist rates is backwards. The heavier bullet (or mono) needs a faster twist rate to stabilize. The 1:8" is faster than the 1:8.5". If you are wanting to shoot the 127 LRX, absolutely stick with the 1:8", not the 1:8.5". Meaning the bullet makes a full 360° revolution in the barrel every 8" instead of 8.5". Much better choice. Allows you to shoot a 140-143 also for target shooting. You might even consider a 1:7.5", since the shorter length is going to leave a lot of velocity on the table. Slower velocities also require faster twists to shoot the heavier bullets or monos and stabilize them well.

As for barrel length, unless your can is a 9", I would be looking at a 20" minimum with the 6.5CM. 22" would be even better. You are probably looking at 2800fps max from an 18" barrel with the 127 LRX. My daughter shoots a 22" 6.5SLR, and gets 2925fps suppressed with a 130 Berger OTM. Absolutely slays game. Mule deer bucks from 454, 532, 637, and pronghorn from 260 & 391. She shoots the 127LRX up to 2955fps or the 124 Hammer Hunter at 3001fps. With the lower BCs, 300 yards is a cakewalk, even out to 500. Make sure you get a heavy enough contour to limit barrel sag with the can.

Action, go with the Defiance. Way, WAY lighter than an R700, and the money you would spend on an R700 to bring it up even close would probably be comparable in costs to the Defiance. True and square action, recut threads, side bolt release, M16 extractor, fluted bolt, bolt knob, alloy bolt shroud, firing pin bushing....it adds up very fast to get similar features, plus, you still have an R700 action. Unless you already have the action off a free donor, the Defiance makes way more sense.

Hawkins makes amazing DBM bottom metal.

This is my daughter's 22"+7" can 6.5SLR for length reference against a 20"+9" can 6.5SS.
View attachment 234993
View attachment 234994
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Those rifles are pretty sweet! Would love to know which manufacturer made the stock on your bottom rifle...
 
ModernRedneck said:
Those rifles are pretty sweet! Would love to know which manufacturer made the stock on your bottom rifle...
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Manners PRS2. I have 3 of them and love them.
20181227_153002.jpg
 
VLD Pilot said:
If that chart is true, you wouldn't lose much by staying with a 20" barrel. Even an 18. Hard to say which powder was used. I think those results may change depending on the powder used. Only my opinion since I've never done a barrel length test on that cartridge.
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By going from 22" to 18", you lose 111fps with that Hornady factory ammo. I think, if anything, with good handloading and tailored powder burn rate and charge weights, that number could grow.
Out to 300 yards, not a big deal. Out to 600-700, makes bullet performance on game become iffy.

We all know, once you get the LR bug, be it with targets or animals, you always look for that next step....

If you have numerous rifles you can choose from, building a short rifle for thick cover or stand hunting can make sense. But if you only have 1 or 2, building a more universal rifle is a bonus. Some compromises need to be made to work over a wider set of rules.
 
lancetkenyon said:
By going from 22" to 18", you lose 111fps with that Hornady factory ammo. I think, if anything, with good handloading and tailored powder burn rate and charge weights, that number could grow.
Out to 300 yards, not a big deal. Out to 600-700, makes bullet performance on game become iffy.

We all know, once you get the LR bug, be it with targets or animals, you always look for that next step....

If you have numerous rifles you can choose from, building a short rifle for thick cover or stand hunting can make sense. But if you only have 1 or 2, building a more universal rifle is a bonus. Some compromises need to be made to work over a wider set of rules.
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Right on. I'd say most here have at least dozen rifle options so this point is pretty moot. I know I have many more than I use. Kinda like the wife's shoes.
 
I'll say I did that barrel length test with a .308 years ago. Started at 26". Ended up at 22". The difference was more significant using RL15 and shooting 185s than with Varget using 150s. I use the 150-168s much more today and for a closer range deer rifle so decided to chop it down to 22". Much has to do with powder and bullet weight choice. In your case, the 120 in the 6.5 CM seems pretty unaffected by the barrel shortening.
 
VLD Pilot said:
Right on. I'd say most here have at least dozen rifle options so this point is pretty moot. I know I have many more than I use. Kinda like the wife's shoes.
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Great point. I should mention to all that I already shoot a 6.5-300 Weatherby for extended long range hunting and wanting to shoot out to 1,000 yards once in a blue moon. I also have a lot more in other calibers.

The custom build I'm working on will mostly stay under 300 yards in a hunting scenario. And will push for further distances at the range with my buddies.
 
VLD Pilot said:
I'll say I did that barrel length test with a .308 years ago. Started at 26". Ended up at 22". The difference was more significant using RL15 and shooting 185s than with Varget using 150s. I use the 150-168s much more today and for a closer range deer rifle so decided to chop it down to 22". Much has to do with powder and bullet weight choice. In your case, the 120 in the 6.5 CM seems pretty unaffected by the barrel shortening.
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After looking more into the data, I'm leaning to the 120 grain Barnes for Mississippi hunting.
 
ModernRedneck said:
After looking more into the data, I'm leaning to the 120 grain Barnes for Mississippi hunting.
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I decided that the 115-130 grain bullets perform superbly on whitetail deer provided you can keep impact velocities around 2000 fps. Regardless of caliber. My experience is with 243/264/277 caliber bullets. Soon to find out how the .257 bullets in that weight range work. I'm certain based on all the threads I've read on guys shooting the 257 of some kind, that it will as well. I had great experiences with heavier also but seems like the animal takes the full energy dump in the lighter bullets with broadside hits as most bullets are found in the opposite side under the hide. Same hits with the .264/277/284 bullets weighing over 130 grains seem to exit on most hits. Frontal shots being the exception. Most of my instate hunting here is similar to yours and ranges are inside 200 yards with exceptions.
 
lancetkenyon said:
This was a test on Rifleshooter.com
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So...I want to throw this out for everyone to chime in on. Based off your test from Rifleshooter.com, I pulled the muzzle velocity for an 18" barrel and loaded in the Barnes 120 grain data into Carbon Six' Twist Rate Calculator. See attachment for the recommended twist rate...

Note (From the Carbon Six Site): "This Twist Calculator Calculator is a tool for determining the Gyroscopic Stability (GS) of your bullet and is based on the Don Miller twist rule. This calculator is used to find the optimal twist rate for your bullet. This is a general information calculator and there may be additional parameters that can have slight effects."

According the trust rate calculator, it's showing that a suggested twist of 8.8. So, if I will primarily be using this bullet, should I still go with an 1:8 twist or would 1:8.5 be better???

I know I know...folks keep saying 1:8...but wanted to double check after seeing this data.
 

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I "think" I've settled on the build. Though there are two things I'm still not sold on yet, as I've decided to make this a 300 yard max hunting rifle (most shots will be under 150 years) and just do another PRS build for a 1,000 yard toy.

Action: Defiance Anti
Barrel: Carbon Six 18" Carbon Barrel, 1:8" twist, threaded for 5/8"x24 (Contemplating 16.5", plus my 7.5" suppressor would put me at an OAL of 24")
Stock: AG Composites, AG Adjustable Chalk Branch Carbon Fiber Stock
Trigger: Trigger Tech Diamond
Bottom Metal: Hawkins
Magazine: MDT
Suppressor: Energetic Armament VOX-S, with Dead Air KeyMount Muzzle Brake

Two things about barrel length I'm still hung up on:
1. The Carbon Six twist rate calculator says I should do 1:8.5 for the barrel and bullets I will be using. I'm don't understand why folks keep saying 1:8 or 1:7.5. I'm sure you all have good reasons for the 1:8, I just understand why the twist rate calculator shows something different. Help me understand please!
2. Contemplating a 16.5" barrel. Once I add my 7.5" suppressor, I would be at an OAL of 24". This would be great for my normal hunting conditions.
 
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