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Problems with Accuracy out of 2 AR10Ts

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Replied by lotoofla on topic Re:Problems with Accuracy out of 2 AR10Ts

This process was used to confirm what the RCBS 'Pecision Mic' was telling me. If you use Stoney Point, RCBS, or any other tools to measure what the free bore relationship with your bullet, then your at the mercy of what ever the manufactures cone angle is. What I did with this process is to eliminate all of the variables, by using the actual bullet I intened to use with the actual chamber, and seating it out to find the real bullet jump. As to your suggestion of loosely inserting the bullet then take a measurement I'm afraid it won't work reliably, and here's why. After the loose bullet has been pushed into position, upon extraction the bullet will rub against the wall of the chamber, then the lugs of the barrel extension and finaly come out of the ejector door. I don't think the bullet will hold it's position very well. When I did it my way with a dummy bullet, I used a Redding Competion bullet seater adjusting the seater .005" at a time. When the cartridge fell out, I backed off the seater to .005" then with a different dummy round I began seated at 001" for a final measurement. This way I could see how far off the RCBS Precision Mic was actualy off. I have seen various ways to make this measurement both in print and in person, but I think my way is best. Tom
Last edit: 13 years 10 months ago by lotoofla. Reason: greater clarification
13 years 10 months ago #4677

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Replied by lotoofla on topic Re:Problems with Accuracy out of 2 AR10Ts

This is for making measurements in the living room of your house.
13 years 10 months ago #4679

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Replied by Hebs on topic Re:Problems with Accuracy out of 2 AR10Ts

I'm actually switching up my load and trying a new one. I'm currently getting inconsistant results with my 150gr sierra pro hunters. First shot is where it's suppose to be, but the following shots are not going where I want them to. Just for kicks I'm gonna try some 155gr Berger VLDs with a different powder (IMR 4350) . I just put a Geissele trigger in yesterday. What a difference. No more white trigger finger... :)
13 years 10 months ago #4680

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Replied by JustMe on topic Re:Problems with Accuracy out of 2 AR10Ts

lotoofla,

I can see if you are using the bolt's extractor to remove the loose brass/bullet, it would be a problem keeping the bullet length from changing as the brass/bullet was tossed about. Instead, I was envisioning keeping the bolt locked back, then pushing the loose brass/bullet into the chamber with your fingers. After the brass/bullet is fully seated against the lands with your fingers, gently tilt the rifle back so the brass/bullet gently falls back into the ejection port. You would then gently roll it out of the port into your hand. I figured after you did this a couple of times and the measurements were consistent, you could be confident the bullet didn't move in the brass when you removed it from the chamber. This may be totally impractical as I haven't tried it.

Hebs, I think I read somewhere (Armalite Tech Library or the Sierra Reloading Manual) said not to use a slower powder than 4064 because it would burn too slow causing ejection problems. I think 4350 is slower than what Armalite recommends.
13 years 10 months ago #4691

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Replied by lotoofla on topic Re:Problems with Accuracy out of 2 AR10Ts

Your right that IMR 4350 is too slow. If I said that, then I was wrong (can't find the post). You will never find ANY LOAD info from Armalite, as using ANY reloaded ammo in you rifle will null and void your warranty. The info you saw came from Sierra Bullets refering to loading for the NM M-14 (M1-A).
13 years 10 months ago #4697

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Replied by a Guest on topic Re:Problems with Accuracy out of 2 AR10Ts

There are some of the old time guys that are using 4350 in the M1 grands now with out hurting the opp rods. They are glueing 1/2" aluminum channel in the underside of the forward handguard for an opp rod guide and using an adjustible gas plug as a pressure dump. This is an easy mod to do and is a store bought item now. Armstrong is shooring 490s with an M1 in the matches with this set up using 4350. We are also doing the same with the M14 with retiming the gas system and using an adjustment valve. BMS has seen these rifles now.
As far as Armalite goes they have put out lots of tech sheets over the years and as I went looking around on their site some are not there any more. The one that stated that only a 308 using 168gr bullets is the only caliber that the A10 should be chambered in is gone or it voids the warranty. Funny thing they announced the 243 coming back out on this site. Time to keep up with the Jones or get left behind. Now some of these old tech sheets are MIA.
Now most of these slow powders can be used in these rifles if you have a smith properly time the rifle. I use ww760, 4831, and R25 in the 260s that I shoot across the course but they have a plus 4" gas system and are timmed to the cal being used with less pressure than the 308 uses to opperate the system. The new floating gas piston that we have started production on will not be able to use these powders without a good adjustment system. That brings me back to Armalite with voiding the warranty with reloads. The ammo on the store shelf does not list the load on the box. Question is is it a slow burning powder or is it a powder used that gave the most constant pressure curve. These boxes don't say do not use in an Armalite. Is the warranty void for using the hot Remington ammo or is Armalite passing the buck if a failure occurs. I think we all know whats goung to happen here. Factory ammo makers use slow burning powder at times such as a powder shortage as we just had. The funny thing is Rem,DPMS,RockRiver and the other black gun makers are less concerned about the ammo used but say use the best ammo, military surplus ie reloads are OK but are not voiding the warranty. They have more confidants in their product line than Armalite does.MSH
Last edit: 13 years 10 months ago by a Guest.
13 years 10 months ago #4707

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Replied by lotoofla on topic Re:Problems with Accuracy out of 2 AR10Ts

I have a AR-10(T) with a 24" barrel, and I thought it was short cycling. What I described to ArmaLite is that it was actually FAST cyling. They first said that "the rifle was designed to work with bullet weights from 150-175grs with 168grs being ideal". They offered to have the gas port rejetted to work more reliably with the 175gr load that I was using. But they would'nt shorten the barrel to 20". When it comes time to buy more W760 you might want to look at H414 as well as it is the exact same thing. Look at Hodgdons web site, find load data for 308win using 175-190gr bullets, and they list both side by side, same start load, same velocity, same max load, same velocity. Tom
13 years 10 months ago #4714

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Replied by Hebs on topic Re:Problems with Accuracy out of 2 AR10Ts

Hey guys, good catch on the 4350... I'm putting that in my Rem700 30-06 loads. I was loading both the day I replied and for some reason had that in my head. I'm using 4895 for the AR-10. Thanks for lookin out though!!
13 years 10 months ago #4725

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Replied by CST on topic Re:Problems with Accuracy out of 2 AR10Ts

any updates?
13 years 8 months ago #5344

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Replied by banjobob on topic Re:Problems with Accuracy out of 2 AR10Ts

Sort of. I sent both back on July 17 and still am waiting. I spoke with someone in the repair dept. They confirmed that both rifles failed to shoot 1moa. (Remember this is the second time I've gone thru this). He said he was going to replace the barrels with the national match barrels, but were not in stock and would have to wait. This was about 4 weeks ago. I called 10 days ago and was told the rifles were done but were waiting on accuracy checks and would be completed by early last week. I was told they would call before shipping them. I still have not heard anything. I'm wondering if they didn't pass muster yet again???

I'm anxious to get the rifles to shoot the way they are advertised, but when I reflect on my experience Id be hard pressed to do it again knowing what I know now. We bought the guns January 2010, We've owned them for 9 months. It's never shot as it was advertised and has spent aprox 4 months back at armalite. There's no telling how much money I've spent on ammo to confirm they don't shoot and have spent aprox $150 just in shipping and insurance.

Remember were talking about 2 guns and all has been confirmed by armalite. I understand an occasional lemon gets out, but 2 in the same family? 2 trips back to the factory for the same problem? I know many on this board have had very different experiences but I hope everyone can understand my frustration with armalite. I wish I had bought a DPMS. :(
13 years 8 months ago #5355

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