5R mil-spec

[cohunter1]

A question for those more knowledgeable about ballistics than I. Does the 1 in 10 twist in these barrels stabilizes a 180 gr bullet, or do they prefer a heavier weight bullet? I am thinking of one, and have lots of 180's for 300 win mag.
Thanks for any input.




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[tomt]

This might help:
JBM - Calculations - Stability

I have the 5R in .308 Win, Betsy is her name.

 

[cohunter1]

That is an awesome link. Very helpful info. That's why I love this forum, somebody always has an answer. Thanks again TomT



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[twoftagl]

308 or 300wm? and where are you in CO?

 

[tomt]

The 5R 300 win mag has a 1-10 twist, the 5R 308 win has a 1-11.25 twist.

 

[cohunter1]

I am in Pagosa Springs waiting for it to turn into winter, but I am looking for a new 300 win mag in a 5R. I already have a 308 that shoots 1/4 moa if I can get my head in the same place every time.Was wondering if a 180 gr would stabilize in a faster twist, and apparently it will, so I am on the hunt for a 5R mil spec.


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[twoftagl]

I'll be moving to CO Springs here in January, and have a 5r in 300wm. I'm assuming your 308 is a 5r? and you're looking for a 5r in 300wm?

I believe the twist in your 308 is kinda non-standard (11 1/4 if I remember correctly) so it can handle the 168 and 180 slugs, but don't have the specs in front of me. With the 300/5r you'll have a 1 in 10 and no problems stabilizing up to and past 210, and I believe even 230.

I'm currently trying to work up a load in my 300wm 5r, didn't have much success with a newer powder, Magpro (but fantastic velicities) so I'm going with one of the standbys for caliber: H4831sc. That should get me going for next season with all summer to practice.

From what I've seen so far, I can't get mine to shoot decidedly better than a moa, but it consistently shoots right at with the cheapest factory ammo out there. Sometimes a tad more, sometimes a tad less. I'm hoping a good load workup can bring it consistently under, so I can push my max out a little further.

I just wish it was as much of a tack driver as the 308 5r's.

Good luck and keep us posted!


Chris

 

[cohunter1]

twoftagl,
Welcome to CO. My 308 is in a sendero, and after a little tweaking, I can brag on it. Thinking of a 300 wm 5r for a couple reasons, but I can almost guarantee to make your 5r shoot sub moa with pet load, and am looking forward to doing that with one of my own soon.


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[billn17]

My 2 cents. I have a rem 700 300 win mag with the 26" sen barrel and it likes the 190 smk's. those are being pushed with 84gr of WC-872 @ 3090 fps. Fed Cases trimmed to 2.610, OAL of 3.500, with a short jump to the lands. Right now I'm getting .30" groups at 100 yrds and just 2 weeks ago worked my way out to 1000 yrds and was only 1.5 high and 1" to the right. So ya I'm very pleased. Something for you to try.

 

[twoftagl]

twoftagl,
Thinking of a 300 wm 5r for a couple reasons, but I can almost guarantee to make your 5r shoot sub moa with pet load, and am looking forward to doing that with one of my own soon.

I'm intrigued at this baited hook and must bite....oh please do tell.

 

[cohunter1]

My shooting partner and I haven't met a sendero we can't make shoot yet. The secret is in the action and barrel being properly torqued to the stock. We are currently trying to prove the theory that we can make a sendero and or 5r mil spec shoot any suitable load. I'm not a physicist, but my theory, is that you have to match the load to the harmonics and resonance of the barrel through tension. It sounds like a truck load of BS, but it has been working so far.


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[brentc]

My shooting partner and I haven't met a sendero we can't make shoot yet. The secret is in the action and barrel being properly torqued to the stock. We are currently trying to prove the theory that we can make a sendero and or 5r mil spec shoot any suitable load. I'm not a physicist, but my theory, is that you have to match the load to the harmonics and resonance of the barrel through tension. It sounds like a truck load of BS, but it has been working so far.


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Your theory isn't far off at all. After some experimentation, I found my Rem actions shoot best right around 35-40 in/lbs.

Back to the topic. I have a 300 Win 5R and shoot nothing but 215s and 230s. The 1/10 works great. And the rumors are true. With good handloads the 5Rs are 1/2 MOA rifles. With great handloads they do even better.

 

[twoftagl]

That doesn't sound like BS....afterall, we all know how important the relationship is of the stock and the action mating..... and shoot, them screws is what what holds em togetherlightbulb.

So I'm supposin the best way to work it is: pick ANY load that shoots decent, do a group or two at each torque setting within acceptable torque values, say 30 - 60 or 65 if it's pillar bedded, and see which one shoots better. That close to what y'all been doin?

After you find the smallest groups, now do a load workup? I'm headed out today to shoot that 4831sc and I think I just might have to adjust my plan a little.....hmmmmmmm.....

Infact, the more I think about it, the more this makes sense. I've always had my action screws really snug. Right now they're the tightest they've ever been at 65 by recommendation of the smith that bedded it, the Tq wrench mfg, and a couple other sources. This might be why I can't seem to get decidedly better than a MOA. What increments do you find make a difference? 5in/lb increments about as close as you go? Thanks for putting that out there!



Chris

P.S. sorry for getting too far off your topic, didn't intend to hijack :-(

 

[cohunter1]

twoftagl,

My ? about twist rate and stability has been satisfied, so I am happy to tell anyone who will listen about torqueing your rifle. My buddy and I have gone to custom length Bell & Carlson stocks (14.25") on our senderos. A friend of ours is part owner in greybull precision, and I am in love with their stock design built by B&C. Anyway, after I decide on respectable load group, start at 50 in lb on both front and rear screws. Shoot 3-5 shots, and if bigger than 1 moa, go to 51 in lb on front screw and so on by 1 in lb on front screw until you are shooting one ragged hole groups. I don't think it makes a huge difference where you start ( 50, 60, 65 in lbs) as long as you start equally on both screws, and increase front screw from there. At some point in this process, your groups will open back up, and you will have to go back down in poundage until your back to the tightest possible groups. Like I mentioned earlier I think you can make any suitable load shoot well by following this process. And so far , it has been repeatable, if you have to remove the stock for whatever reason. Hope you have as good of luck as I have doing this.


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