260 Rem Load Question

[Compact45]

I'm loading 41g of H4350 in lapua brass, 139 scenars, and WLR primers seated at 2.80 in my GAP 260 with very good repeatable accuracy. When I loaded 41.6, .7m .8 I was getting shinny ejector marks on the head stamp but no bolt issues and stayed at 41g. I hear some are loading 42.5g-43g of H4350 so I just wanted to hear if I'm good at 41g or if I should (if it is safe) to progress with a higher charge.

Your experience is needed and appreciated!

Thanks.

 

[harley_jeff]

Re: 260 Rem Load Question

I worked my load up from 41 grains H4350, Gap 10 .260, to where I ended up (42.0) but I am using Nosler brass. I have not loaded any Lapua brass but while searching for load info, I have read that Lapua brass has a lower internal capacity, therefore raising pressure at lower powder load than what you read about others using.

My bottom line was to slowly work up a load for MY rifle, and find a safe load for it. Hopefully others with more wisdom than I have will chime in soon.

 

[p33shooter]

Re: 260 Rem Load Question

Im using 43graing of h4350, 139SC jumping to the lands using Lapua brass and 210M primers in my GAP260. Shoots one hole all day long if I do my part.

If your getting the Ejector mark stop there and back off a little, What velocity are you running and are you jumping or jamming the bullet?

 

[harley_jeff]

Re: 260 Rem Load Question

Im using 43graing of h4350, 139SC jumping to the lands using Lapua brass and 210M primers in my GAP260. Shoots one hole all day long if I do my part.

What velocities are you seeing with the load?

My 42.0 in Nosler bras at 2.80 OAL runs 2695 fps.

 

[Compact45]

Re: 260 Rem Load Question

I am loading these at 2.80 and they touch the rifling at 2.850. I don't have an insert yet for 6.5mm to measure off the olgive. I did testing with different COL using 41g and the best was a 2.80, I can post a pic if needed. My next step is to chrono this load, hopefully very soon, so I don't have the numbers yet. What FPS should I be expecting normally?

Can you explain the difference between jumping and jamming. I thought all bullets jumped unless they are touching the lands. Is that the difference?

Thanks.

 

[p33shooter]

Re: 260 Rem Load Question

Compact45,
My loads using the 139sc measure 3.168 COL using Hornady Comparator. Im pushing them out at 2790-2800FPS out of a 22 inch Bartlein barrel.

Im not the best at explaining things but for a rule of thumb VLD bullets like to be jammed into the lands, Berger Bullets are a good example. The 140VLD's like to be at 3.200 COL in my rifle and at the lands the length is 3.178. So the bullet jams .022 into the rifling. VLD's offer a lower drag due to less of a contact surface with the barrel. The problem with them is they end up being long and usually do not fit in the magazines.

Jumping the bullet is the most common practice with most manufactures, you tend to have lower pressures than you do if you Jam it or load it at the edge of the rifling. SMK's or SC have a larger barrel contact surface that aids in stabilizing the bullet that the VLD's don't have. So you can jump them.

I'm sure someone will punch holes in my attempt to explain this, o'well...

 

[mnhntr]

Re: 260 Rem Load Question

I had better accuracy jumping the 140gr VLDs set .020 off the lands in my LRP 26in tube.

 

[p33shooter]

Re: 260 Rem Load Question

some people have good luck with jumping VLD's and Berger has a good article on their website about it.

I have had better luck with the jam on VLD's

 

[Compact45]

Re: 260 Rem Load Question

P33Shooter,

Comparing apples to apples can you measure your col from base to tip without using the comparator? I know I need to pick up the 6.5 insert for mine soon.

Heres a pic of the 5 shot groups I'm getting with my load.

 

[p33shooter]

Re: 260 Rem Load Question

sorry, I dont have any loaded up now, I shot the last yesterday when I was working on the 338. You can probably shrink it down just a little more with some tuning, but that is a good group.

I forgot that your using the ar10 platform and not a bolt gun. I haven't done any load development for my Ar10 yet.

 

[Compact45]

Re: 260 Rem Load Question

It's a bolt gun built on the Templar action. Which way would you go to tune it a little?

Will pressure increase with a longer col if I don't touch the lands. I know shorter will increase pressure due to compression. So, if I go longer and groups open up would increase powder charge to see if it balances out? I'm not sure on this one...

 

[p33shooter]

Re: 260 Rem Load Question

Compact,
I got you guys mixed up, now that I know you have the bolt you got a way to go with it. George used a Bartlein barrel on my build with a standard 260 chamber, did you spec a standard chamber?

I looked at my records and the 139SC touches the lands at 3.188 and I seat them at 3.168(using a Hornady Comparator), so you have a .020 jump. IF we have the same Chamber and you load at 2.80 magazine length you would be jamming the bullet into the lands. IF this is correct on my end you are getting higher pressure because of that. You should seat your bullet at around 2.73-2.72 (not using a comparator) as a start and leave it at 41 grains of H4350 for now. Work on the seating length and once your happy with the grouping then add powder.

This is my 5 shot group using 43.0 of H4350 and 139SC at 3.168COL. I add a little powder when summer comes around.

139SC by livnpaintball, on Flickr

 

[p33shooter]

Re: 260 Rem Load Question

I had to break the barrel in as well, forgot to add that.

 

[Compact45]

Re: 260 Rem Load Question

P33Shooter,

Mine is a Bartlein barrel as well but I do not have the chamber spec on it, I picked it up from KCShooter here on the Hide about 1 year ago. Do you know if GAP has this information on file and would provide it?

When I measure base to tip the 139SC touch the rifling at 2.850 and I'm seating them at 2.80 without the comparator. I wonder if mine is chambered for a shorter bullet since we have a difference in COL, if we are measuring the same way.

I'll check my round count tonight but the barrel should be broken in.

 

[p33shooter]

Re: 260 Rem Load Question

Something is wrong here, measuring mine from tip to base without comparator it is 2.74 to the rifling using 139sc bullets. You dont have a short chamber for sure, If anything it has a long throat.

When I use a Hornady comparator I include the inch that the comparator adds to the measurement. That might muddy the water a little. So the 3.168 is actually 2.168 to the bullet ogive using the Hornady comparator.

 

[Compact45]

Re: 260 Rem Load Question

Ummm, OK, my 2.850 to touch the rifling is from base to tip and my loaded COL is 2.80 from base to tip. So, I'm thinking I have .050 jump before the bullet contacts any rifling.

How does this match with your chamber measurements and what does it mean for mine...am I to short in my COL or something? Thoughts?

I have 329 rounds down the tube.

 

[tigerfan_9]

Re: 260 Rem Load Question

Scenars are .63-.65 ojive to tip(if i recall) so if you are touching the rifling at 2.85 your base to ojive should be about 2.2 . Loading 0.05 off the lands seems a bit far, most seem to be running 0.010 off or as little as 0.005 but to get that close you better have consistent equipment and measure to the ojive b/c it won't take much to put you in the lands.

 

[p33shooter]

Re: 260 Rem Load Question

PM sent on this

 

[p33shooter]

Re: 260 Rem Load Question

sounds like your throat is wore out, you can have it rechambered and barrel set back by GAP for a small fee. I'm guessing..

 

[Compact45]

Re: 260 Rem Load Question

OK. Any way to check it before I send it off or should I keep shooting it with my current load?

The previous owner had this load. I'm not far from it considering the lapua case volume.

139 gr. Lapua Scenar
41.6 grains H4350
Rem 260 case
CCI Br Primers
3/8" groups from this loading.
COL 2.82

 

[p33shooter]

Re: 260 Rem Load Question

a good local gunsmith can look at it and should be able to tell you what shape it is in.

 

[captain zeke]

Re: 260 Rem Load Question

Tag will give y'all some feed back when I get home on this round

 

[psinclair]

Re: 260 Rem Load Question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: harley_jeff</div><div class="ubbcode-body">I worked my load up from 41 grains H4350, Gap 10 .260, to where I ended up (42.0) but I am using Nosler brass. I have not loaded any Lapua brass but while searching for load info, I have read that Lapua brass has a lower internal capacity, therefore raising pressure at lower powder load than what you read about others using.

My bottom line was to slowly work up a load for MY rifle, and find a safe load for it. Hopefully others with more wisdom than I have will chime in soon. </div></div>

FYI:

.260 empty case weights

WW(7/08)= 156.5grs
RP= 161.7grs
Nosler/Norma= 167.3grs
Lapua= 172.0grs

 

[harley_jeff]

Re: 260 Rem Load Question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: PGS</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: harley_jeff</div><div class="ubbcode-body">I worked my load up from 41 grains H4350, Gap 10 .260, to where I ended up (42.0) but I am using Nosler brass. I have not loaded any Lapua brass but while searching for load info, I have read that Lapua brass has a lower internal capacity, therefore raising pressure at lower powder load than what you read about others using.

My bottom line was to slowly work up a load for MY rifle, and find a safe load for it. Hopefully others with more wisdom than I have will chime in soon. </div></div>

FYI:

.260 empty case weights

WW(7/08)= 156.5grs
RP= 161.7grs
Nosler/Norma= 167.3grs
Lapua= 172.0grs</div></div>

So does the greater empty case weight indicate thicker walls etc and therefore lower internal capacity? Sorry for not understanding as I'm still trying to learn.

 

[psinclair]

Re: 260 Rem Load Question

That is correct....reduce loads a smidge when using heavier brass. Especially if you are running your loads near the top.

 

[wchartz]

Re: 260 Rem Load Question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: P33Shooter</div><div class="ubbcode-body">Compact45,
My loads using the 139sc measure 3.168 COL using Hornady Comparator. Im pushing them out at 2790-2800FPS out of a 22 inch Bartlein barrel.

Im not the best at explaining things but for a rule of thumb VLD bullets like to be jammed into the lands, Berger Bullets are a good example. The 140VLD's like to be at 3.200 COL in my rifle and at the lands the length is 3.178. So the bullet jams .022 into the rifling. VLD's offer a lower drag due to less of a contact surface with the barrel. The problem with them is they end up being long and usually do not fit in the magazines.

Jumping the bullet is the most common practice with most manufactures, you tend to have lower pressures than you do if you Jam it or load it at the edge of the rifling. SMK's or SC have a larger barrel contact surface that aids in stabilizing the bullet that the VLD's don't have. So you can jump them.

I'm sure someone will punch holes in my attempt to explain this, o'well...
</div></div>I just finished developing a load for my 260. I tried SMK 142,123, Berger 140 VLD, Hornady 140 AMax and Lapua 139. The Lapua was by far the most accurate in my rifle. .26 MOA vs. .75 MOA. I found that setting the Lapua back about .030 worked best for me. Jamming the bullets .005 or .010 gave a little less accuracy but the thing that I really did not like was that my SD and ES went up significantly when the bullets just touched the lands or was jammed up to .010. It got a little more consistant at .020 jam but not as good as backing off the lands.
Also note that Sierra has two style match kings, at least in 6.5mm they do. The 140 and 120 are more conventional and the 142 and 123 are VLD.

 

[Compact45]

Re: 260 Rem Load Question

I found my chrono data and with my 41g for H4350, Lapua brass, 139 Scenars, and WLR seated at 2.80 which is .050 off the lands I'm getting 2800 fps. I will have to do more chrono work but that was my initial test. I posted the group earlier in this thread. So, anyone know how I am getting this FPS with my load and other are using more powder for the same FPS with Lapua brass and a different primer?

Am I just lucky with this load or is there something arise here?

 

[wchartz]

Re: 260 Rem Load Question

My barrel is 25" and my load is 139 Lapua, 42.6/H4350, Fed. 210M, Lapua brass for 2825 fps. No sign of excessive pressure.

 

[Gruffskin]

Re: 260 Rem Load Question

Ive found doing initial test without a chrono makes it hard to know if the load you have is going to satisfy your requirements. Once I chrono'ed what I thought to be a light charge weight, I was more than happy even though it wasnt at max compared to what I see on this site.

With the 139's I was seeing people load charges go above 45 of H4350, I didnt need all that to meet my requirements.

 

[leadbullet]

Re: 260 Rem Load Question

I run 142 SMK's in lapua 260 brass with 43.5 gr of H4350 without any pressure signs, I do load at 2.870 COAL. accuracy is a hair below 1/2 MOA and making hits at 1250 is a breeze at 2850 FPS.
try loading longer.

 

[Friar]

Re: 260 Rem Load Question

I'm loading 142 SMK's in lapua 260 brass with 42.0 gr of H4350. I do seat to 2.887 COAL. Consistently groups well under 1/2 MOA in my TRG. I do not have a chrono to measure velocity. I've got one box of 139 gr. Scenar's sitting on my bench and plan on loading those for an upcomomng f-class shoot to see how they perform. I've shot the SMK's out to 500 yards and they performed well.