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Posted: 5/2/2017 4:22:29 PM EDT
| I've been looking at getting a Faxon 16 inch barrel for a lightweight build I'm working on. I know pencil barrels move as they heat up, I was wondering how much of an impact it has on the accuracy. I'm looking to use this build for hog hunts, so generally fewer than ten shots at a time, usually only one or two. Is barrel heat going to be an issue? If I were to do a 30 round course of fire how much of a difference would that make? |
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I did some heat/accuracy test with my SR15's 'LW' barrel before.
You can read and look at the pictures, here The accuracy test is after a 90rd mag dump. I also did another test using a SPR thick profile SS barrel, and the group size, similar to the 'LW' barrel, also became 3 times as big as it is from a cold barrel when it is hot after the 90rd mag dump |
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Quoted:
My last pencil barrel would open up to 4-5 moa after 30 rounds in about 10 minutes. But based on your use, you should be fine. That's what pencil barrels are for. The profile of the barrel roughly determines how many rounds until its "hot". If the pencil barrel cannot meet your needs, I'll eat my shorts. |
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If the pencil barrel cannot meet your needs, I'll eat my shorts. Check this out op. YouTube: pencil barrel test |
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Quoted:
I did some heat/accuracy test with my SR15's 'LW' barrel before. You can read and look at the pictures, here The accuracy test is after a 90rd mag dump. I also did another test using a SPR thick profile SS barrel, and the group size, similar to the 'LW' barrel, also became 3 times as big as it is from a cold barrel when it is hot after the 90rd mag dump In other words, would a .223 identical load do the same thing ? Not that it really matters... still minute of man within the effective range..... and certainly as good as a LtWt barrel can be expected to do. |
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Pertaining to your linked thread... I wonder if the CBC , being 5.56, if chamber heat soak had anything to do with the groups opening up that much. In other words, would a .223 identical load do the same thing ? Not that it really matters... still minute of man within the effective range..... and certainly as good as a LtWt barrel can be expected to do. Quoted:
Quoted:
I did some heat/accuracy test with my SR15's 'LW' barrel before. You can read and look at the pictures, here The accuracy test is after a 90rd mag dump. I also did another test using a SPR thick profile SS barrel, and the group size, similar to the 'LW' barrel, also became 3 times as big as it is from a cold barrel when it is hot after the 90rd mag dump In other words, would a .223 identical load do the same thing ? Not that it really matters... still minute of man within the effective range..... and certainly as good as a LtWt barrel can be expected to do. The AE 50gr Varmint Tipped was more accurate than the CBC 77gr OTM with a hot barrel, and the group size was 2.5 times bigger, not 3.5 times bigger like the CBC. I know it is not the same cartridge/bullet/manufacturer, but at least we see that ammo difference matters too when talking accuracy w/ a hot barrel. BTW, this is my most recent 'hot barrel' test with the CBC 77gr OTM... IMO it did much better this time(~5.7MOA down to ~4.4MOA) : I also did the same test with the same gun same barrel, SR15 Mod1 'LW' barrel, using the Black Hills 77gr TMK, with the same setup and indoor range, and the result is only slightly better than CBC 77gr OTM. I do not have the picture of the TMK result, but it was ~4MOA. The BH TMK 77 shoots 1.5-1.6MOA while the CBC 77 OTM is consistently 1.25MOA with a cold to slightly warm (75F~160F) barrel. 
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Quoted:
My last pencil barrel would open up to 4-5 moa after 30 rounds in about 10 minutes. But based on your use, you should be fine. That's what pencil barrels are for. |
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Your groups opened 5 moa after firing only three rounds per minute for 10 minutes? That seems excessive. 3 rounds per minute shouldn't put that much heat into the barrel. That's only 1 round every 20 seconds. Quoted:
Quoted:
My last pencil barrel would open up to 4-5 moa after 30 rounds in about 10 minutes. But based on your use, you should be fine. That's what pencil barrels are for. The Spikes never gave me an issue with heat, unless I have the can on. I am sure that is ME, and not the can. Having said; going through 2 mags in a couple of minutes has never yielded a 5 MOA shift. I know there can be an issue, but those numbers seem excessive. |
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