@ 06:44 am (GMT)
I have a howa 6.5x55 which shoots barnes 120ttsx and berger 130vlds really nicely though I have both projectiles about 1.3mm off the lands which leaves me with 4.5-5mm in the neck of the case (excluding boat tail)
I am about to stabilise the fore end and bed the action, I was wondering if it would be worth getting my local gun Smith to reduce the free bore by 1.5- 2mm to ensure sufficient projectile remains in the neck whilst remaining close to the lands with my preferred projectiles?
It took quite a lot of load development to get this far, partly because of the flexy hogue stock.
Or is this a bit of a waste of money on a budget rifle? Would i be better to just shoot it as is, taking care to maintain Concentricity of the loaded rounds?
@ 09:19 am (GMT)
Re: Free boreword on street Bud is the Barnes LIKE a goodly sized jump........
@ 10:42 am (GMT)
Re: Free borehi mark i also shoot the 6.5x55 and have found that they don't mind a good jump. I'm currently shooting 140grain amax 46grains of ar2209 with a 3mm jump to the lands.(via nathans instructions i think?) i have loaded closer and further and honestly didn't notice enough difference to shout about.
@ 09:49 pm (GMT)
Re: Free boreHi Mark, a long freebore is normal for the Swede. You could shorten the jump to seat close, but would then lose around 100fps and with no gain in accuracy. To gain accuracy, the rifle may need a good birthday. Forum member Jon Short did the same with his Howa / Hogue rifle, turned out a treat.
@ 03:29 am (GMT)
Re: Free boreThanks Mike, Sebastian & Nathan,
When I was working up my loads I had no idea the stock was a problem, I found loading them long improved the accuracy however in hind site that may well have coincided with different/improved shooting technique (holding the fore end immediately in front of the floor plate)
So I guess I'll stabilise the fore end & squeeze the projectiles down a bit further then see how it goes before front & rear bedding.
Nathan I searched for Jon's mods and found reference to him stabilising the fore end, bedding, trigger work, bolt lapping and Barrel polish.
I'm all set for step 1 & 2 once your compound arrives, my local GS said he cant do much with the more recent Howa triggers except lube the sears (I think he said, so I was considering a timney) bolt lapping is covered in your book which I can try and if Ive got some money left and room for more accuracy try a barrel polish.
Just out of interest what causes the loss of 100fps with shortening the free bore? is it the reduced case volume thus increase in pressure requiring a reduced powder load? wont I still lose that with a longer jump?
Im getting about 2800fps with 50g of 2213sc with the 120s
@ 10:07 pm (GMT)
Re: Free boreHave a read of this Hornady literature on chamber pressures Mark, l found it very helpful early on!
And as said many times get Nathans books so you will know how to tune your rifle and set out a plan to achieve your goals.
As for the hact trigger, find a better option than the your LGS as these are straight forward to work on. Timmneys are very good but not necessary on these with the small amount of work needed to the sear engagement and spring weight.
After reading Nathans books you a better understanding of the mechanics involved.
@ 04:31 am (GMT)
Re: Free boreThanks Martin, that's a good article, I understand the drop in pressure & velocity with the longer jump. Good to know I can tune the existing trigger too, cheers.
I probably wasn't very clear, I was thinking of removing the barrel, re reaming the chamber to shorten the free bore slightly to optimise bullet seat and jump. Thus I thought Nathan was saying I'd lose 100fps by doing that.
Anywho, stabilising & bedding will most likely help considerably, I can get 3/4 inch groups at 100m with factory rifle set up & my reloads as long as the barrel doesn't touch the fore end!
I have Nathans rifle Accurizing & reloading books, Id have to say highly recommended.
@ 10:48 pm (GMT)
Re: Free boreYes that is what Nathan is saying Mark, the large jump is a head start for the projectile before hitting the lands, an easy gain in velocity used in many SAMMI spec calibres.
The 308w is a great example that we have been discussing in other posts not long ago and regarded as a very accurate, easy to tune calibre that produces good velocities for case size & l think is the most efficient cartridge available.
I wont write up how to tune the trigger but have a look it, relatively straight forward, honing the sear and sorting the spring as Nathan writes about in his book.
Take your time with the bedding it's very rewarding, you will have a relatively cheap shooter for years to come!