Gunsmithing Freebore

[sniperaviator]

How do I solve this problem?
1. Most rifles shoot their most accurate with the bullet close or even touching the lands. You won't know until you try it, but I want the option of being able to load jammed to the lands and also have some "room to grow" as the lands wear.

2. AICS magazines can take 2.88" oal as their longest round. Sinces I want room to grow, I think maybe 2.84" OAL on a 308 155gr Lapua Scenar is the length to be jammed to lands. That way I can load shorter by .020 and still get the max powder load in the case (47 grains) and load touching the lands.

3. So how do I get my gunsmith (or find a gunsmith) that can build my chamber to my specs? Is there some way to solve this problem in a general way (ream the chamber very short and the have a tool that can make it longer--any length?).

It's not just me, a lot of people are running into this problem.

It is very frustrating to load longer and longer rounds and see the group size go from 1" down to 1/2" and then not be able to get those rounds in the magazine. There is also a maximum length that will feed into the reciever if you could get a longer magazine. So a longer magazine might not solve this, it would require a different reciever too.

 

[bohem]

Re: Freebore

You can get a reamer cut with 0 freebore and then get a caliber specific, universal reamer to set the freebore/throat dimensions at whatever you want...

Or you can put together a couple of dummy rounds at the specific length you're like to start from and mail them off to custom reamer makers. I happen to like dealing with Dave Kiff from PTG.


If you call Dave up and tell him you have a 308 and want to shoot 175 SMK's in AICS mags at 2.82-2.84" OAL to start there's a good chance he already has a reamer on file that will do the job exactly.

Personally I like having the reamer cut to the specific freebore and throat dimensions rather than running a throater in there afterwards.

This problem is common, yet the solution is easy and well known amongst custom builders.

 

[ChadTRG42]

Re: Freebore

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sniperaviator</div><div class="ubbcode-body">I want the option of being able to load jammed to the lands </div></div>
Why are you wanting to load jammed? It is a benchrest technique, and not for hunting, match or tactical ammo. You will create more problems jamming them, than seating the bullet out long (~2.820 ish) .020" off the lands or so.
To answer your question, load up a dummy round to give to your gunsmith to throat the rifling at a certain COAL.

 

[sniperaviator]

Re: Freebore

Why do I want to load jammed? That is the same question my gunsmith said. As if tactical rifles don't deserve maximum accuracy. Yet gunsmiths are always willing to sell you OTHER accurizing options, polished bolts, lapped bolts, new barrels. But when it comes to throat length it's "you get what I give you".

And for your information, in my Rem 700, jammed to the lands was 2.96"!

If Sako can get it right, why can't others?

 

[ChadTRG42]

Re: Freebore

I'd be looking for a different gunsmith, then. If the gun is to be used for 100 and 200 yard benchrest shooting and matches, then jamm em up. If you plan to hunt or shoot it in a match or shoot longer than 400 or 500 yards, then jamming them is not the way to go. You will drastically increase you extreme spreads when jamming bullets, which is not good for vertical dispersion at 500 + yards. And if you have to extract a loaded round, there's a good chance you will leave the bullet stuck in the rifling. I have seen this several times. Your rifle is out of commision until you clean it out. Your reloading technique is more a benchrest style, and not for a 308 with a 155 Scenar. I'm just trying to help, so don't take my comments offensive. If so, don't ask for opinions.

 

[sniperaviator]

Re: Freebore

You don't know until you try it. You find a powder charge that gives best accuracy. Then you vary OAL and find the best OAL that gives best accuracy. Then vary the powder charge on that OAL.

Maybe all the way jammed is NOT the way to go. But 1 or 2 100ths off is pretty close to jammed and from what I understand lands tend to get further away as the barrel wears.

So it isn't about jamming or not jamming, but BEING ABLE to jam (or close to it) if that is where best accuracy is.

1/2" at 100 yards translates to 5" at 1000 yards and maybe, just maybe means a hit or a miss.

At any rate, it's generally a good thing to have nice tight groups, regardless.

Just looking for a solution. Basically trying to build a rifle around a bullet. And some things you cant change, some things you can. Seems like freebore, you can vary that one.

 

[ChadTRG42]

Re: Freebore

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sniperaviator</div><div class="ubbcode-body">1/2" at 100 yards translates to 5" at 1000 yards </div></div>
Nope, this statement isn't correct. Seems you haveit all figured out, then. Just keep reading up on reloading and ballistics, and learn all you can. There's a lot of info here to read.

 

[Slinky001]

Re: Freebore

The following is not a solution, but rather a few things to think about:

Jamming the bullet into the lands can cause pressure problem and lead to some funky vertical dispesion at times.

Making the O.A.L. just off of the lands leads to other issues because throat length can change over time (depending on caliber someimes quickly; example 6.5-.284)

You can soft seat bullets into the rifling by using neck tension between .001-.002 less than bullet diameter and it will seat the bullets as the bolt is closed.

Or you can pull the bullet 0.020 off of the lands and jump them. Sierras fair very well like this!

If you choose to do anything that involves puting the bullets into the lands, remember that if you need to remove a round for any reason once chambered your likely hood of pulling that projectile out is very high. Shortly after you do this you will also realize that you action is now full of powder and you can not clean it out very easily!

I"m certainly not saying not to do it, but if you are shooting anything other than benchrest, consider it carefully!

Food for thought!
Brian

 

[Hateca]

Re: Freebore

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sniperaviator</div><div class="ubbcode-body">How do I solve this problem?
1. Most rifles shoot their most accurate with the bullet close or even touching the lands. You won't know until you try it, but I want the option of being able to load jammed to the lands and also have some "room to grow" as the lands wear.
</div></div>

Not sure where you got this from but this isn't entirely accurate. There can't be a blanket statement pertaining to all rifles and cartridges.

That being said if you feel you want to be able to mag feed and jam then seed a dummy cartridge that is loaded with an OAL according to SAMMI and send the dummy round to PTG or some other reamer manufacture to have them make you a reamer. I'm not a fan of cutting throats in a separate operation.

As for Remington having a long throat there is a practical and liability reason behind it since most manufactures will tell you they do not warrantee any weapon that has had reloads shot through it, so it would be a mute point as to the question of jamming the lands into a factory Remington.

 

[bigwill214]

Re: Freebore

I guess when you ask a question knowing everything, it is hard to listen to the guys that do this stuff for a living. JHMO

 

[Graham]

Re: Freebore

From Berger:

"... What has been discovered is that VLD bullets shoot best when loaded to a COAL that puts the bullet in a “sweet spot”. This sweet spot is a band .030 to .040 wide and is located anywhere between jamming the bullets into the lands and .150 jump off the lands.

Since the sweet spot is .030 to .040 wide we recommend that you conduct the following test to find your rifles VLD sweet spot:

Load 24 rounds at the following COAL if you are a hunter (pulling a bullet out of the case with your rifling while in the field can be a hunt ending event which must be avoided) or a competition shooter who worries about pulling a bullet during a match:

1..010 off the lands (jump) 6 rounds
2..050 off the lands (jump) 6 rounds
3..090 off the lands (jump) 6 rounds
4..130 off the lands (jump) 6 rounds

Shoot 2 (separate) 3 shot groups in fair conditions to see how they group. The remarkable reality of this test is that one of these 4 COALs will outperform the other three by a considerable margin. Once you know which one of these 4 COAL shoots best then you can tweak the COAL +/- .002 or .005."

Because you don't have a particular load in mind for a rifle build, try the above before you spend any more money.

 

[sniperaviator]

Re: Freebore

I think it is possible to do what I want. Factory 308 rounds are usually 2.80" (or shorter). Correct me if I am wrong.

My AICS magazine will hold rounds 2.90" long, but that is pushing it, I think you need some play in there for reliability so lets call it 2.88".

So there is the distance between 2.8" and 2.88" that I have to work with.

However, anything less than 2.85" becomes a problem because I can't get a full load of powder in the case.

The two bullets with the best BC, that buck the wind the best are Lapua Scenar 155's and the Berger 155's. I am choosing the Lapua Scenars. I can purchase those, Berger seems to be on and off with availability on their bullets. Also, Sierra makes a 155 Palma bullet that is a clone of the 155 Lapua Scenar. There are no clones or second source for the Bergers. The Berger is a VERY pointed bullet and would have to have an even shorter chamber than the Scenars, I believe (I haven't actually measured them).

Look, I'm just trying to figure out how to solve a problem. I am willing to pay for my own custom reamer. How would I spec the length of the reamer?

I have a Sako TRG that sort of "got it right". At least better than the Remington 700. A 155 Lapua Scenar jammed to the lands just barely will fit in the Sako magazine and can just barely be loaded that long without falling out of the case. I can put my 2.94" Lapua Scenars in my TRG magazine and they will chamber reliably.

As for liability issues has anyone ever heard of a rifle accident being caused by a bullet being loaded too close to the lands? Any documented cases of this happening? Berger recomends loading close or touching the lands. I haven't heard of any accidents but that doesn't mean there aren't any. What is the safety issue here?

As for a round falling apart, I've never had that happen. If it did, I could deal with it. I carry a dowel that I can tap a bullet out with.

There may be another solution and that involves AW magazines which will hold rounds up to 2.94". What recievers will load rounds longer than 2.88"?? I don't think Remington's will at least not without modification. Going this route involves changing bottom metal etc. Probably more expensive than a custom reamer.

Anyone know what recievers will accept AW magazines?

Anyone know how to modify a Remington reciever to accept the longer rounds?

 

[bigwill214]

Re: Freebore

This link will show you where to modify your action. I know it is for something different but the concept is the same.

http://www.competitionshootingstuff.com/sitebuildercontent/sitebuilderfiles/rts_rtm_instructions.pdf

I believe it is also not so much the receiver as the bottom metal that makes the difference whether it can take AW mags or not.

 

[sniperaviator]

Re: Freebore

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BigWill214</div><div class="ubbcode-body">I guess when you ask a question knowing everything, it is hard to listen to the guys that do this stuff for a living. JHMO </div></div>

n.a. , I'm a compulsive meddler.

I've had a frustrating experience with a barrel that HAS sufficient accuracy, if I could load practical rounds long enough to come close to the lands. But I can't and I am trying not to make the same mistake twice.

 

[bigwill214]

Re: Freebore

Ok I get where you are coming from but why try to re-invent the wheel?

 

[bohem]

Re: Freebore

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sniperaviator</div><div class="ubbcode-body"> I am willing to pay for my own custom reamer. How would I spec the length of the reamer? </div></div>

I mentioned this early on.

Make a few dummy rounds up (usually 3) and mail them off to your custom reamer grinder of choice, my personal preference is to call PTG and speak to Dave Kiff. After all of my bothersome meddling he remembers my name and is quite helpful.

They're a 'Hide sponsor as well.

541-826-5808

 

[Hateca]

Re: Freebore

I believe this has been said but go too much over mag length in the AICS mag will require you to notch the feed ramp to clear the bullet tip and you will still be limited.

However if you send in a dummy round to the PTG like has been mentioned several times they can make the reamer to your stated specs and dummy rounds. Short of that you're not going to achieve what you want.

If you want to use AW mags you will need to mod the Remington reviver to get this to work and this isn't a DIY job, I've done many of these mods.

The other option is to get the Guardian receiver I designed with Defiance Machine that is cut from the get go for AW mags. Several other builders on here have now started using this same reviver with their private brand. Do a little searching and you will find it.

As for there having been any documented danger or damage done to a rifle from being too close or jammed into the lands. Define danger or damage.

Common sense would tell one that too close or jammed into the lands could initiate a pressure issues, danger. If one isn’t careful they could at least stick their bolt closed and worse blow the weapon to a point of making it not workable, damage. There has been numerous post on this forum alone, with photos, of just what can happen with too high of pressure, poor reloading technique, poor prep, and so on.

Chasing lands is over rated in almost every case.

 

[sobrbiker883]

Re: Freebore

shoot more, conjecture on internet less......

 

[jrob300]

Re: Freebore

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sobrbiker883</div><div class="ubbcode-body">shoot more, conjecture on internet less......

</div></div>

Yup.

Conventional internet wisdom is that VLD bullets do not like to be jumped. I called Swampy at JLK and asked about the 210 JLK VLD's... he said he'd never tried it and I wouldn't know if I didn't. So I loaded some to mag. tolerant length (jumping over 1/4") and they shot the smallest group EVER out of my 300 WM. 5 shots into .200".

.02

John

 

[Swan]

Re: Freebore

I have an even better idea. Instead of trying to get a .308 to shoot like a 6.5 caliber (ie. really fast 155's) just build a 6.5?

Problem solved. Your COAL will probably be 2.83-.85 or any other length you choose, and will outshoot any fast .308.

 

[jrob300]

Re: Freebore

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Swan</div><div class="ubbcode-body">I have an even better idea. Instead of trying to get a .308 to shoot like a 6.5 caliber (ie. really fast 155's) just build a 6.5?

Problem solved. Your COAL will probably be 2.83-.85 or any other length you choose, and will outshoot any fast .308. </div></div>

.260 Rem. What the .308 <span style="text-decoration: line-through">would </span>should have been if the military wasn't so enamored with .30 cal.

John

 

[former naval person]

Re: Freebore

Did anybody notice that he said the powder was too compressed to seat the bullet deep enough for the magazine?

 

[sobrbiker883]

Re: Freebore

But he's not just a sniper, he's a flying sniper.......

Build a 6.5 if you want 6.5 performance. Better yet, build a .284 and shoot .6+ BC boolits.

 

[sniperaviator]

Re: Freebore

OK. so I decide to build a 260 remington. Reason? It bucks the wind better. Just have my smith put a 260 barrel on it and, uh throat it. Hmm, same magazine will I have the same problem? What reamer for 139 Lapua Scenar bullets?
I want them to kiss the lands and still fit in my AI magazine.

 

[Swan]

Re: Freebore

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sniperaviator</div><div class="ubbcode-body">OK. so I decide to build a 260 remington. Reason? It bucks the wind better. Just have my smith put a 260 barrel on it and, uh throat it. Hmm, same magazine will I have the same problem? What reamer for 139 Lapua Scenar bullets?
I want them to kiss the lands and still fit in my AI magazine.

</div></div>

Copy exactly what you stated above and email it to your smith. Done deal. AI mags are fine.

fwiw, I run the 139's jammed at about 2.840". Plenty o room in me mag.

 

[bohem]

Re: Freebore

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sniperaviator</div><div class="ubbcode-body">OK. so I decide to build a 260 remington. Reason? It bucks the wind better. Just have my smith put a 260 barrel on it and, uh throat it. Hmm, same magazine will I have the same problem? What reamer for 139 Lapua Scenar bullets?
I want them to kiss the lands and still fit in my AI magazine.

</div></div>

This exact problem is a VERY easy fix.

Call PTG and order the "260 Roscoe" reamer. Mr William Roscoe of Lousiana Precision Rifles (wnroscoe on here) has been kind enough to let us in on his particular bolt action reamer specs for a 260 with the 140 class bullets in it.

I spent some time working through measurements, making dummy cases, calling Mike Bush and bugging him about stuff and then read on here that Mr. Roscoe's reamer was public disclosure. When I called Dave Kiff he had a print emailed to me, low and behold it's almost exactly what I'd come up with through research, measurements, and bothering the builders on here who have been kind enough to answer my questions.

I just ordered one of the "260 Roscoe" reamers and was done with it.

 

[joemagee]

Re: Freebore

sniperaviator, just for ref. my .308 reamer from PTG has only .057 free bore that puts my 175mk. at 2.79 with slight .010 jam, but a 155sm palma bullet just touching will measure 2.885 ish... thats a bite long, I would get a reamer with maybe only .010 free bore that would put your 155s at a workable length.. best to make a few dummy rounds and send them to Dave @ PTG good luck and take your time when ordering a reamer, make sere its what you want....