troy fairweather
Member
Wish I had the money, it's nice just having the brass around even if not needed. Gunwerks has onefired brass for pretty cheap. I want some 6.5prc when I get the money, can't beat $45/100 for adg brass.
Mountain Rifle - Kimber 84M Proof Research .308 Win
- Thread starter MCMXI
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I should probably be taking it easy but I tried some Black Hills Gold 155gr A-MAX ammunition this afternoon. I haven't cleaned the barrel yet so shot three rounds to "season" and adjust the scope. I then shot the 5-round group shown below. I feel that this load will probably shoot better than I show but it was decent for sure. The vertical stringing could be down to me but so far this barrel is looking good from 155gr to 175gr. I have some Hornady SST to try plus a bunch of other stuff, but after the SST this weekend if I'm up to it I'll move onto handloading.
troy fairweather
Member
Do they still make the 155, they always seemed to shoot good, poped a few deer with them.
Nature Boy
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I have an update or two on this project. Proof installed a new 24" barrel on an 84M receiver that I had provided a while back but I wanted to move the barrel to a different (prototype) 84M receiver. I had to do a little "machining" to the receiver to enable it to eject fired brass since the ejection port has a 70 degree opening rather than the standard 140 degree opening, and I wasn't able to move the ejector or change the extractor geometry. Proof hadn't made the extractor clearance cut in their barrel deep enough so I had to remove .020" from the bottom of the cut to prevent the nose of the extractor from crashing into the barrel. In addition, when I installed the barrel, the bolt wouldn't quite close on a GO gage so I lapped the bolt lugs to the receiver to remove a couple of thousandths and now the bolt is just slightly tight when closing on a GO gage. It was tight enough before lapping that some factory ammunition was hard to chamber. Another thing I worked on was the magazines and feeding. The rifle functions quite well now with a smooth feed, good extraction and good ejection. I'd still like to have the receiver and bolt salt nitrided to make the contact surfaces as hard as possible which should further improve the smoothness of the bolt. Speaking of function, I added an adjustable cheek piece to the stock.
I checked the COAL for both 178gr A-MAX and 175gr LRX bullets to see if I can get the bullet to touch the lands but still fit in the AICS magazines. With the 178gr bullet on the lands the COAL is 2.840", and with the 175gr LRX on the lands the COAL is 2.915". Both of those loads will fit in the AICS magazine which has an internal length of 2.985" after I removed the front binder plate. I'll be working up a 178gr A-MAX load shortly which might help reduce the number of LRX bullets I need to go through to get an LRX load figured out as well. I want to use the LRX for hunting and the A-MAX for everything else.
The rifle as shown below with a Vortex Viper PST 6-24x50mm scope, Nightforce rings, EGW rail and SilencerCo Harvester suppressor weighs in at an even 9lb. The 10 round AICS magazine adds a little over 4oz to the overall weight. The intent for this rifle is for it to be a lightweight tactical rifle that can also be used for hunting deer and elk or any other suitable critter. A sling and Harris bipod might bring the overall weight to around 10lb which is decent for what it is. I plan on adding at least two flush cups to the stock. I might rebed the recoil lug too since I had bedded it for a different receiver. The rifle is still a bit of a Frankenstein at the moment but eventually it'll be finished properly once I have everything where I need it to be.
The target below shows a 7-shot group shot today at 100 yards using Hornady BLACK 168gr A-MAX ammunition. The upper right shot was from a cold/clean bore with six more shots to use up a box that I had laying around. This rifle seems to perform well with a variety of factory loads and I have no doubt that it'll be shooting small groups using handloads. Overall I'm quite pleased with how this project is going.
7-shot group
I checked the COAL for both 178gr A-MAX and 175gr LRX bullets to see if I can get the bullet to touch the lands but still fit in the AICS magazines. With the 178gr bullet on the lands the COAL is 2.840", and with the 175gr LRX on the lands the COAL is 2.915". Both of those loads will fit in the AICS magazine which has an internal length of 2.985" after I removed the front binder plate. I'll be working up a 178gr A-MAX load shortly which might help reduce the number of LRX bullets I need to go through to get an LRX load figured out as well. I want to use the LRX for hunting and the A-MAX for everything else.
The rifle as shown below with a Vortex Viper PST 6-24x50mm scope, Nightforce rings, EGW rail and SilencerCo Harvester suppressor weighs in at an even 9lb. The 10 round AICS magazine adds a little over 4oz to the overall weight. The intent for this rifle is for it to be a lightweight tactical rifle that can also be used for hunting deer and elk or any other suitable critter. A sling and Harris bipod might bring the overall weight to around 10lb which is decent for what it is. I plan on adding at least two flush cups to the stock. I might rebed the recoil lug too since I had bedded it for a different receiver. The rifle is still a bit of a Frankenstein at the moment but eventually it'll be finished properly once I have everything where I need it to be.
The target below shows a 7-shot group shot today at 100 yards using Hornady BLACK 168gr A-MAX ammunition. The upper right shot was from a cold/clean bore with six more shots to use up a box that I had laying around. This rifle seems to perform well with a variety of factory loads and I have no doubt that it'll be shooting small groups using handloads. Overall I'm quite pleased with how this project is going.
7-shot group
troy fairweather
Member
I really like the looks, shooting good to.
@troy fairweather, thanks ... I think it'll be great with the two handloads that I'm planning on working up. Lapua brass, GM210M primers and Varget powder. I've found that it shoots just about everything to the same point of aim with factory ammunition ranging from 150gr to 175gr. I'm hoping that the A-MAX and LRX loads have similar velocity and similar poa/poi.
troy fairweather
Member
Shooting same poa is a good sign, it's very close to the rifle build I have in my head. Mine would be a 7 mm tho. Hope one day to have the money to build one.
One more thing, I'm most likely going to order an EGW rail with a 30 moa (8.7 milrad) cant built in. The rail shown has 0 moa cant and with the scope zeroed at 100 yards I only have 7.5 milrad of up and 12.5 milrad of down adjustment 
. The PST only has 20 milrad of vertical adjustment from stop to stop. With the 30 moa rail, it will shift the center to a much better 16.2 milrad up and 3.8 milrad down which would give me sufficient adjustment to get out to 1200 yards. Not that I need to get out to 1200 yards but the current 7.5 milrad up is just not right. I could order the cheaper and in stock 20 moa rail that would get me 13.3 milrad up and 6.7 milrad down. 13.3 milrad would get me out to 1075 yards but I like the idea of having more if I ever need it.
I've been saying this for years but Kimber can't compete in the heavy tactical market but they could do very well in the lightweight tactical market. The rifle above has almost every feature that I want in a lightweight tactical rifle including a locking bolt handle, complete package under 10 lb (scope, rings, bases, suppressor, magazine, sling and bipod) , detachable magazine and adjustable cheek piece. If the LOP was adjustable and a two-stage trigger was available it would be an awesome package. The trigger is from TriggerTech and it's certainly better than the Kimber trigger but it's a single stage which isn't my preference for a precision rifle.
. The PST only has 20 milrad of vertical adjustment from stop to stop. With the 30 moa rail, it will shift the center to a much better 16.2 milrad up and 3.8 milrad down which would give me sufficient adjustment to get out to 1200 yards. Not that I need to get out to 1200 yards but the current 7.5 milrad up is just not right. I could order the cheaper and in stock 20 moa rail that would get me 13.3 milrad up and 6.7 milrad down. 13.3 milrad would get me out to 1075 yards but I like the idea of having more if I ever need it.I've been saying this for years but Kimber can't compete in the heavy tactical market but they could do very well in the lightweight tactical market. The rifle above has almost every feature that I want in a lightweight tactical rifle including a locking bolt handle, complete package under 10 lb (scope, rings, bases, suppressor, magazine, sling and bipod) , detachable magazine and adjustable cheek piece. If the LOP was adjustable and a two-stage trigger was available it would be an awesome package. The trigger is from TriggerTech and it's certainly better than the Kimber trigger but it's a single stage which isn't my preference for a precision rifle.
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troy fairweather
Member
Did you chrono any of the loads yet, does the can add any fps.
troy fairweather said:
No, not yet. I would expect to get around 2,600 fps for the 175gr and 178gr loads fairly easily but I'll start using the chronograph during load development. Typically the suppressor adds 50 fps to 75 fps, or at least that's what I've seen. Once I have loads worked up I'll shoot them with the brake installed to see how much of a velocity change there is over suppressed use.
Nature Boy
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Fantastic results!
@Nature Boy & @LoonWulf, thanks. I think it's going to get a lot better once I start load development. I bought 300 pieces of Lapua brass a while back so am hoping for greatness out of this rifle. I'll most likely rebed the recoil lug before the weekend and start putting loads together. I haven't kept up with the latest and greatest powders for .308 Win so is Varget still a good choice? I have lots of Reloder 15 and Varget but figure that Varget is less temperature sensitive so for me in Montana it would be a better choice. Barnes shows CFE 223 to be the most accurate powder they tested for the 175gr LRX and it gave the highest velocity too, but I've never heard of that powder. Clearly I need to do some digging.
RL 15 gives me about 100fps over varget. I can’t say whether it’s more or less accurate than varget. I have a couple of 308 Kimber hunting rifles. I use Winchester brass because it’s thinner and allows an extra grain of powder . What is the balance like with the suppressor attached? I have wanted to try a suppressor on my mountain ascent as it has a threaded barrel. You have a nice rifle there.
troy fairweather
Member
How temp sensitive is cfe223?
I cant say too much about low temp, but not much change between 70 and +100. I switched from 748 to cfe223 exclusively.
troy fairweather
Member
I've never really had any problems with temp, but here some powders can vary a lot. Going for 10° - 70° in a day or two is pretty common here. I don't hunt last 400 yards often but last that there my be problems with temp sensitive powders. I am thinking of using more 4831sc if I can get some, should cover my 7mms and the prc.
Casefull said:
I used to use Reloder 15 exclusively for .308 Win handloads for my F-Class rifle when I lived in Hawaii. It was always warm there so I had no issues re large temperature fluctuations. I used to use Lapua brass, 178gr A-MAX bullets and Federal match primers with 44.2gr of Reloder 15. Velocity was around 2,650 fps from a 26" barrel with excellent accuracy.
The balance point of the rifle shown above is centered in the chamber area of the barrel. Kind of how it's shown in the picture balancing on the post. If you add a suppressor to your Mountain Ascent I suggest that you find the lightest one available. TBAC and SilencerCo have good options. I have no experience with TBAC other than communicating with the very knowledgeable and very intelligent Zak Smith in combination with endless positive comments from very knowledgeable members here and on other forums. It seems like there's no way to go wrong with a suppressor from TBAC ... I'll have to get some from them eventually.
@LoonWulf, Powder Valley has CFE223 available. It's supposedly good at reducing copper fouling, meters well and gives good velocity. If it's temperature insensitive I might have to order an 8lb jug or two. I'm looking for as much velocity as I can safely get since I want to maximize the effective range of the LRX bullet. Barnes shows the CFE223 as giving more than a 100 fps advantage over Varget.
"Hodgdon CFE 223 Smokeless Powder
Introduced in January 2012, this versatile, spherical rifle propellant incorporates in its formula CFE, Copper Fouling Eraser. This ingredient, originally used in military propellant, greatly deters copper fouling. It contributes to longer periods of top accuracy with less barrel cleaning time. Being a spherical powder, metering is superbly accurate. CFE 223 yields top velocities in many cartridges such as the 204 Ruger, 223 Remington/5.56mm NATO, 22-250 Remington and the 308 Winchester/7.62mm NATO, plus many, many more. Match, Varmint and AR shooters will love this one!"
https://www.powdervalleyinc.com/product/hodgdon-cfe223/
LoonWulf said:
I'm more concerned with going from 60°F to -10°F than the other way since load development for me is typically spring and early summer with hunting in the winter.
Regarding CFE223, a member on another forum who seems to shoot a lot and keep good notes saw a 2 fps/1°F increase in velocity when the temperature ranged from 62°F to 92°F. He was shooting a .223 Rem. A video test at -51°F and 79°F saw a 1 fps/1°F velocity change, also a .223 Rem. I found a chart from an unknown source listing the temperature sensitivity of CFE223 to be 1.7 fps/1°F. This is far from conclusive but the general feeling I'm getting is that CFE223 is definitely more temperature sensitive than Varget. I'll do some more digging but I'm inclined to start with Varget and see what I get for velocity. If I can get 2,650 fps with the LRX I'll be content I think.
Yeah cant say anything in regards to the swing the other way. I dont think ive noticed that much of a swing but my normal usage range is much narrower as you know lol.
Vargets never a bad choice, its kinda the h1000 for the 45gr cases.
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